Merge pull request #156 from schungx/master

Immutable strings and built-in common operators

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "rhai"
-version = "0.14.1"
+version = "0.15.0"
 edition = "2018"
 authors = ["Jonathan Turner", "Lukáš Hozda", "Stephen Chung"]
 description = "Embedded scripting for Rust"
@@ -20,26 +20,22 @@ categories = [ "no-std", "embedded", "parser-implementations" ]
 num-traits = { version = "0.2.11", default-features = false }
 
 [features]
-#default = ["no_stdlib", "no_function", "no_index", "no_object", "no_module", "no_float", "only_i32", "unchecked", "no_optimize", "sync"]
+#default = ["unchecked", "sync", "no_optimize", "no_float", "only_i32", "no_index", "no_object", "no_function", "no_module"]
 default = []
 unchecked = []      # unchecked arithmetic
-no_index = []       # no arrays and indexing
-no_float = []       # no floating-point
-no_function = []    # no script-defined functions
-no_object = []      # no custom objects
+sync = []           # restrict to only types that implement Send + Sync
 no_optimize = []    # no script optimizer
-no_module = []      # no modules
+no_float = []       # no floating-point
 only_i32 = []       # set INT=i32 (useful for 32-bit systems)
 only_i64 = []       # set INT=i64 (default) and disable support for all other integer types
-sync = []           # restrict to only types that implement Send + Sync
+no_index = []       # no arrays and indexing
+no_object = []      # no custom objects
+no_function = []    # no script-defined functions
+no_module = []      # no modules
 
 # compiling for no-std
 no_std = [ "num-traits/libm", "hashbrown", "core-error", "libm", "ahash" ]
 
-# other developer features
-no_stdlib = []      # do not register the standard library
-optimize_full = []  # set optimization level to Full (default is Simple) - this is a feature used only to simplify testing
-
 [profile.release]
 lto = "fat"
 codegen-units = 1

RELEASES.md

@@ -1,6 +1,70 @@
 Rhai Release Notes
 ==================
 
+Version 0.14.2
+==============
+
+Regression fix
+--------------
+
+* Do not optimize script with `eval_expression` - it is assumed to be one-off and short.
+
+Bug fixes
+---------
+
+* Indexing with an index or dot expression now works property (it compiled wrongly before).
+  For example, `let s = "hello"; s[s.len-1] = 'x';` now works property instead of causing a runtime error.
+
+Breaking changes
+----------------
+
+* `Engine::compile_XXX` functions now return `ParseError` instead of `Box<ParseError>`.
+* The `RegisterDynamicFn` trait is merged into the `RegisterResultFn` trait which now always returns
+  `Result<Dynamic, Box<EvalAltResult>>`.
+* Default maximum limit on levels of nested function calls is fine-tuned and set to a different value.
+* Some operator functions are now built in (see _Speed enhancements_ below), so they are available even
+  under `Engine::new_raw`.
+* Strings are now immutable. The type `rhai::ImmutableString` is used instead of `std::string::String`.
+  This is to avoid excessive cloning of strings.  All native-Rust functions taking string parameters
+  should switch to `rhai::ImmutableString` (which is either `Rc<String>` or `Arc<String>` depending on
+  whether the `sync` feature is used).
+* Native Rust functions registered with the `Engine` also mutates the first argument when called in
+  normal function-call style (previously the first argument will be passed by _value_ if not called
+  in method-call style).  Of course, if the first argument is a calculated value (e.g. result of an
+  expression), then mutating it has no effect, but at least it is not cloned.
+* Some built-in methods (e.g. `len` for string, `floor` for `FLOAT`) now have _property_ versions in
+  addition to methods to simplify coding.
+
+New features
+------------
+
+* Set limit on maximum level of nesting expressions and statements to avoid panics during parsing.
+* New `EvalPackage` to disable `eval`.
+* `Module::set_getter_fn`, `Module::set_setter_fn` and `Module:set_indexer_fn` to register getter/setter/indexer functions.
+* `Engine::call_fn_dynamic` for more control in calling script functions.
+
+Speed enhancements
+------------------
+
+* Common operators (e.g. `+`, `>`, `==`) now call into highly efficient built-in implementations for standard types
+  (i.e. `INT`, `FLOAT`, `bool`, `char`, `()` and `ImmutableString`) if not overridden by a registered function.
+  This yields a 5-10% speed benefit depending on script operator usage. Scripts running tight loops will see
+  significant speed-up.
+* Common assignment operators (e.g. `+=`, `%=`) now call into highly efficient built-in implementations for
+  standard types (i.e. `INT`, `FLOAT`, `bool`, `char`, `()` and `ImmutableString`) if not overridden by a registered function.
+* Implementations of common operators for standard types are removed from the `ArithmeticPackage` and `LogicPackage`
+  (and therefore the `CorePackage`) because they are now always available, even under `Engine::new_raw`.
+* Operator-assignment statements (e.g. `+=`) are now handled directly and much faster.
+* Strings are now _immutable_ and use the `rhai::ImmutableString` type, eliminating large amounts of cloning.
+* For Native Rust functions taking a first `&mut` parameter, the first argument is passed by reference instead of
+  by value, even if not called in method-call style.  This allows many functions declared with `&mut` parameter to avoid
+  excessive cloning. For example, if `a` is a large array, getting its length in this manner: `len(a)` used to result
+  in a full clone of `a` before taking the length and throwing the copy away. Now, `a` is simply passed by reference,
+  avoiding the cloning altogether.
+* A custom hasher simply passes through `u64` keys without hashing to avoid function call hash keys
+  (which are by themselves `u64`) being hashed twice.
+
+
 Version 0.14.1
 ==============
 

benches/engine.rs

@@ -29,7 +29,7 @@ fn bench_engine_new_raw_core(bench: &mut Bencher) {
 
 #[bench]
 fn bench_engine_register_fn(bench: &mut Bencher) {
-    fn hello(a: INT, b: Array, c: Map) -> bool {
+    fn hello(_a: INT, _b: Array, _c: Map) -> bool {
         true
     }
 

benches/eval_array.rs

@@ -61,3 +61,27 @@ fn bench_eval_array_large_set(bench: &mut Bencher) {
 
     bench.iter(|| engine.consume_ast(&ast).unwrap());
 }
+
+#[bench]
+fn bench_eval_array_loop(bench: &mut Bencher) {
+    let script = r#"
+            let list = [];
+            
+            for i in range(0, 10_000) {
+                list.push(i);
+            }
+
+            let sum = 0;
+
+            for i in list {
+                sum += i;
+            }
+        "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine.compile(script).unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}

benches/eval_expression.rs

@@ -41,3 +41,118 @@ fn bench_eval_expression_number_operators(bench: &mut Bencher) {
 
     bench.iter(|| engine.consume_ast(&ast).unwrap());
 }
+
+#[bench]
+fn bench_eval_expression_optimized_simple(bench: &mut Bencher) {
+    let script = r#"
+            2 > 1 &&
+            "something" != "nothing" ||
+            "2014-01-20" < "Wed Jul  8 23:07:35 MDT 2015" &&
+            [array, with, spaces].len <= #{prop:name}.len &&
+            modifierTest + 1000 / 2 > (80 * 100 % 2)
+        "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::Simple);
+    let ast = engine.compile_expression(script).unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}
+
+#[bench]
+fn bench_eval_expression_optimized_full(bench: &mut Bencher) {
+    let script = r#"
+            2 > 1 &&
+            "something" != "nothing" ||
+            "2014-01-20" < "Wed Jul  8 23:07:35 MDT 2015" &&
+            [array, with, spaces].len <= #{prop:name}.len &&
+            modifierTest + 1000 / 2 > (80 * 100 % 2)
+        "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::Full);
+    let ast = engine.compile_expression(script).unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}
+
+#[bench]
+fn bench_eval_call_expression(bench: &mut Bencher) {
+    let script = r#"
+            2 > 1 &&
+            "something" != "nothing" ||
+            "2014-01-20" < "Wed Jul  8 23:07:35 MDT 2015" &&
+            [array, with, spaces].len <= #{prop:name}.len &&
+            modifierTest + 1000 / 2 > (80 * 100 % 2)
+        "#;
+
+    let engine = Engine::new();
+
+    bench.iter(|| engine.eval_expression::<bool>(script).unwrap());
+}
+
+#[bench]
+fn bench_eval_call(bench: &mut Bencher) {
+    let script = r#"
+            2 > 1 &&
+            "something" != "nothing" ||
+            "2014-01-20" < "Wed Jul  8 23:07:35 MDT 2015" &&
+            [array, with, spaces].len <= #{prop:name}.len &&
+            modifierTest + 1000 / 2 > (80 * 100 % 2)
+        "#;
+
+    let engine = Engine::new();
+
+    bench.iter(|| engine.eval::<bool>(script).unwrap());
+}
+
+#[bench]
+fn bench_eval_loop_number(bench: &mut Bencher) {
+    let script = r#"
+        let s = 0;
+        for x in range(0, 10000) {
+            s += 1;
+        }
+    "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine.compile(script).unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}
+
+#[bench]
+fn bench_eval_loop_strings_build(bench: &mut Bencher) {
+    let script = r#"
+        let s = 0;
+        for x in range(0, 10000) {
+            s += "x";
+        }
+    "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine.compile(script).unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}
+
+#[bench]
+fn bench_eval_loop_strings_no_build(bench: &mut Bencher) {
+    let script = r#"
+        let s = "hello";
+        for x in range(0, 10000) {
+            s += "";
+        }
+    "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::None);
+
+    let ast = engine.compile(script).unwrap();
+
+    bench.iter(|| engine.consume_ast(&ast).unwrap());
+}

benches/iterations.rs

@@ -12,7 +12,7 @@ fn bench_iterations_1000(bench: &mut Bencher) {
             let x = 1_000;
             
             while x > 0 {
-                x = x - 1;
+                x -= 1;
             }
         "#;
 

benches/parsing.rs

@@ -32,7 +32,7 @@ fn bench_parse_full(bench: &mut Bencher) {
             2 > 1 &&
             "something" != "nothing" ||
             "2014-01-20" < "Wed Jul  8 23:07:35 MDT 2015" &&
-            [array, with, spaces].len() <= #{prop:name}.len() &&
+            [array, with, spaces].len <= #{prop:name}.len &&
             modifierTest + 1000 / 2 > (80 * 100 % 2)
         "#;
 
@@ -94,7 +94,7 @@ fn bench_parse_primes(bench: &mut Bencher) {
             }
             
             print("Total " + total_primes_found + " primes.");
-            print("Run time = " + now.elapsed() + " seconds.");
+            print("Run time = " + now.elapsed + " seconds.");
         "#;
 
     let mut engine = Engine::new();
@@ -102,3 +102,35 @@ fn bench_parse_primes(bench: &mut Bencher) {
 
     bench.iter(|| engine.compile(script).unwrap());
 }
+
+#[bench]
+fn bench_parse_optimize_simple(bench: &mut Bencher) {
+    let script = r#"
+            2 > 1 &&
+            "something" != "nothing" ||
+            "2014-01-20" < "Wed Jul  8 23:07:35 MDT 2015" &&
+            [array, with, spaces].len <= #{prop:name}.len &&
+            modifierTest + 1000 / 2 > (80 * 100 % 2)
+        "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::Simple);
+
+    bench.iter(|| engine.compile_expression(script).unwrap());
+}
+
+#[bench]
+fn bench_parse_optimize_full(bench: &mut Bencher) {
+    let script = r#"
+            2 > 1 &&
+            "something" != "nothing" ||
+            "2014-01-20" < "Wed Jul  8 23:07:35 MDT 2015" &&
+            [array, with, spaces].len <= #{prop:name}.len &&
+            modifierTest + 1000 / 2 > (80 * 100 % 2)
+        "#;
+
+    let mut engine = Engine::new();
+    engine.set_optimization_level(OptimizationLevel::Full);
+
+    bench.iter(|| engine.compile_expression(script).unwrap());
+}

scripts/fibonacci.rhai

@@ -17,7 +17,7 @@ let now = timestamp();
 
 let result = fib(target);
 
-print("Finished. Run time = " + now.elapsed() + " seconds.");
+print("Finished. Run time = " + now.elapsed + " seconds.");
 
 print("Fibonacci number #" + target + " = " + result);
 

scripts/for2.rhai

@@ -0,0 +1,22 @@
+const MAX = 1_000_000;
+
+print("Iterating an array with " + MAX + " items...");
+
+print("Ready... Go!");
+
+let now = timestamp();
+
+let list = [];
+
+for i in range(0, MAX) {
+    list.push(i);
+}
+
+let sum = 0;
+
+for i in list {
+    sum += i;
+}
+
+print("Sum = " + sum);
+print("Finished. Run time = " + now.elapsed + " seconds.");

scripts/loop.rhai

@@ -6,7 +6,7 @@ let x = 10;
 loop {
     print(x);
 
-    x = x - 1;
+    x -= 1;
 
 	if x <= 0 { break; }
 }

scripts/mat_mul.rhai

@@ -24,9 +24,9 @@ fn mat_gen(n) {
 }
 
 fn mat_mul(a, b) {
-    let m = a.len();
-    let n = a[0].len();
-    let p = b[0].len();
+    let m = a.len;
+    let n = a[0].len;
+    let p = b[0].len;
 
     let b2 = new_mat(n, p);
 	
@@ -38,13 +38,13 @@ fn mat_mul(a, b) {
 
     let c = new_mat(m, p);
 
-	for i in range(0, c.len()) {
+	for i in range(0, c.len) {
 		let ci = c[i];
-		for j in range(0, ci.len()) {
+		for j in range(0, ci.len) {
 			let b2j = b2[j];
 			ci[j] = 0.0;
 			
-			for z in range(0, a[i].len()) {
+			for z in range(0, a[i].len) {
 				let x = a[i][z];
 				let y = b2j[z];
 				ci[j] += x * y;
@@ -62,8 +62,10 @@ let a = mat_gen(SIZE);
 let b = mat_gen(SIZE);
 let c = mat_mul(a, b);
 
+/*
 for i in range(0, SIZE) {
 	print(c[i]);
 }
+*/
 
-print("Finished. Run time = " + now.elapsed() + " seconds.");
+print("Finished. Run time = " + now.elapsed + " seconds.");

scripts/primes.rhai

@@ -2,7 +2,7 @@
 
 let now = timestamp();
 
-const MAX_NUMBER_TO_CHECK = 100_000;     // 9592 primes <= 100000
+const MAX_NUMBER_TO_CHECK = 1_000_000;     // 9592 primes <= 100000
 
 let prime_mask = [];
 prime_mask.pad(MAX_NUMBER_TO_CHECK, true);
@@ -15,7 +15,7 @@ let total_primes_found = 0;
 for p in range(2, MAX_NUMBER_TO_CHECK) {
     if !prime_mask[p] { continue; }
 
-    print(p);
+    //print(p);
 
     total_primes_found += 1;
 
@@ -26,8 +26,8 @@ for p in range(2, MAX_NUMBER_TO_CHECK) {
 }
 
 print("Total " + total_primes_found + " primes <= " + MAX_NUMBER_TO_CHECK);
-print("Run time = " + now.elapsed() + " seconds.");
+print("Run time = " + now.elapsed + " seconds.");
 
-if total_primes_found != 9_592 {
-    print("The answer is WRONG! Should be 9,592!");
+if total_primes_found != 78_498 {
+    print("The answer is WRONG! Should be 78,498!");
 }

scripts/speed_test.rhai

@@ -7,7 +7,7 @@ let x = 1_000_000;
 print("Ready... Go!");
 
 while x > 0 {
-    x = x - 1;
+    x -= 1;
 }
 
-print("Finished. Run time = " + now.elapsed() + " seconds.");
+print("Finished. Run time = " + now.elapsed + " seconds.");

scripts/string.rhai

@@ -11,7 +11,7 @@ print("foo" >= "bar");          // string comparison
 print("the answer is " + 42);   // string building using non-string types
 
 let s = "hello, world!";        // string variable
-print("length=" + s.len());     // should be 13
+print("length=" + s.len);       // should be 13
 
-s[s.len()-1] = '?';             // change the string
-print(s);                       // should print 'hello, world?'
+s[s.len-1] = '?';               // change the string
+print("Question: " + s);        // should print 'Question: hello, world?'

scripts/strings_map.rhai

@@ -0,0 +1,103 @@
+print("Ready... Go!");
+
+let now = timestamp();
+
+let adverbs = [ "moderately", "really", "slightly", "very" ];
+
+let adjectives = [
+  "abandoned", "able", "absolute", "academic", "acceptable", "acclaimed",
+  "accomplished", "accurate", "aching", "acidic", "acrobatic", "active",
+  "actual", "adept", "admirable", "admired", "adolescent", "adorable", "adored",
+  "advanced", "adventurous", "affectionate", "afraid", "aged", "aggravating",
+  "aggressive", "agile", "agitated", "agonizing", "agreeable", "ajar",
+  "alarmed", "alarming", "alert", "alienated", "alive", "all", "altruistic",
+  "amazing", "ambitious", "ample", "amused", "amusing", "anchored", "ancient",
+  "angelic", "angry", "anguished", "animated", "annual", "another", "antique",
+  "anxious", "any", "apprehensive", "appropriate", "apt", "arctic", "arid",
+  "aromatic", "artistic", "ashamed", "assured", "astonishing", "athletic",
+  "attached", "attentive", "attractive", "austere", "authentic", "authorized",
+  "automatic", "avaricious", "average", "aware", "awesome", "awful", "awkward",
+  "babyish", "back", "bad", "baggy", "bare", "barren", "basic", "beautiful",
+  "belated", "beloved", "beneficial", "best", "better", "bewitched", "big",
+  "big-hearted", "biodegradable", "bite-sized", "bitter", "black",
+  "black-and-white", "bland", "blank", "blaring", "bleak", "blind", "blissful",
+  "blond", "blue", "blushing", "bogus", "boiling", "bold", "bony", "boring",
+  "bossy", "both", "bouncy", "bountiful", "bowed", "brave", "breakable",
+  "brief", "bright", "brilliant", "brisk", "broken", "bronze", "brown",
+  "bruised", "bubbly", "bulky", "bumpy", "buoyant", "burdensome", "burly",
+  "bustling", "busy", "buttery", "buzzing", "calculating", "calm", "candid",
+  "canine", "capital", "carefree", "careful", "careless", "caring", "cautious",
+  "cavernous", "celebrated", "charming", "cheap", "cheerful", "cheery", "chief",
+  "chilly", "chubby", "circular", "classic", "clean", "clear", "clear-cut",
+  "clever", "close", "closed", "cloudy", "clueless", "clumsy", "cluttered",
+  "coarse", "cold", "colorful", "colorless", "colossal", "comfortable",
+  "common", "compassionate", "competent", "complete", "complex", "complicated",
+  "composed", "concerned", "concrete", "confused", "conscious", "considerate",
+  "constant", "content", "conventional", "cooked", "cool", "cooperative",
+  "coordinated", "corny", "corrupt", "costly", "courageous", "courteous",
+  "crafty"
+];
+
+let animals = [
+  "aardvark", "african buffalo", "albatross", "alligator", "alpaca", "ant",
+  "anteater", "antelope", "ape", "armadillo", "baboon", "badger", "barracuda",
+  "bat", "bear", "beaver", "bee", "bison", "black panther", "blue jay", "boar",
+  "butterfly", "camel", "capybara", "carduelis", "caribou", "cassowary", "cat",
+  "caterpillar", "cattle", "chamois", "cheetah", "chicken", "chimpanzee",
+  "chinchilla", "chough", "clam", "cobra", "cockroach", "cod", "cormorant",
+  "coyote", "crab", "crane", "crocodile", "crow", "curlew", "deer", "dinosaur",
+  "dog", "dolphin", "domestic pig", "donkey", "dotterel", "dove", "dragonfly",
+  "duck", "dugong", "dunlin", "eagle", "echidna", "eel", "elephant seal",
+  "elephant", "elk", "emu", "falcon", "ferret", "finch", "fish", "flamingo",
+  "fly", "fox", "frog", "gaur", "gazelle", "gerbil", "giant panda", "giraffe",
+  "gnat", "goat", "goldfish", "goose", "gorilla", "goshawk", "grasshopper",
+  "grouse", "guanaco", "guinea fowl", "guinea pig", "gull", "hamster", "hare",
+  "hawk", "hedgehog", "heron", "herring", "hippopotamus", "hornet", "horse",
+  "human", "hummingbird", "hyena", "ibex", "ibis", "jackal", "jaguar", "jay",
+  "jellyfish", "kangaroo", "kingfisher", "koala", "komodo dragon", "kookabura",
+  "kouprey", "kudu", "lapwing", "lark", "lemur", "leopard", "lion", "llama",
+  "lobster", "locust", "loris", "louse", "lyrebird", "magpie", "mallard",
+  "manatee", "mandrill", "mantis", "marten", "meerkat", "mink", "mole",
+  "mongoose", "monkey", "moose", "mosquito", "mouse", "mule", "narwhal", "newt",
+  "nightingale", "octopus", "okapi", "opossum", "oryx", "ostrich", "otter",
+  "owl", "oyster", "parrot", "partridge", "peafowl", "pelican", "penguin",
+  "pheasant", "pigeon", "pinniped", "polar bear", "pony", "porcupine",
+  "porpoise", "prairie dog", "quail", "quelea", "quetzal", "rabbit", "raccoon",
+  "ram", "rat", "raven", "red deer", "red panda", "reindeer", "rhinoceros",
+  "rook", "salamander", "salmon", "sand dollar", "sandpiper", "sardine",
+  "scorpion", "sea lion", "sea urchin", "seahorse", "shark", "sheep", "shrew",
+  "skunk", "snail", "snake", "sparrow", "spider", "spoonbill", "squid",
+  "wallaby", "wildebeest"
+];
+
+let keys = [];
+
+for animal in animals {
+  for adjective in adjectives {
+    for adverb in adverbs {
+      keys.push(adverb + " " + adjective + " " + animal)
+    }
+  }
+}
+
+let map = #{};
+
+let i = 0;
+
+for key in keys {
+  map[key] = i;
+  i += 1;
+}
+
+let sum = 0;
+
+for key in keys {
+  sum += map[key];
+}
+
+for key in keys {
+  map.remove(key);
+}
+
+print("Sum = " + sum);
+print("Finished. Run time = " + now.elapsed + " seconds.");

scripts/while.rhai

@@ -4,5 +4,5 @@ let x = 10;
 
 while x > 0 {
     print(x);
-    x = x - 1;
+    x -= 1;
 }

src/any.rs

@@ -1,6 +1,6 @@
 //! Helper module which defines the `Any` trait to to allow dynamic value handling.
 
-use crate::parser::INT;
+use crate::parser::{ImmutableString, INT};
 use crate::r#unsafe::{unsafe_cast_box, unsafe_try_cast};
 
 #[cfg(not(feature = "no_module"))]
@@ -151,7 +151,7 @@ pub struct Dynamic(pub(crate) Union);
 pub enum Union {
     Unit(()),
     Bool(bool),
-    Str(Box<String>),
+    Str(ImmutableString),
     Char(char),
     Int(INT),
     #[cfg(not(feature = "no_float"))]
@@ -178,6 +178,10 @@ impl Dynamic {
     /// Is the value held by this `Dynamic` a particular type?
     pub fn is<T: Variant + Clone>(&self) -> bool {
         self.type_id() == TypeId::of::<T>()
+            || match self.0 {
+                Union::Str(_) => TypeId::of::<String>() == TypeId::of::<T>(),
+                _ => false,
+            }
     }
 
     /// Get the TypeId of the value held by this `Dynamic`.
@@ -185,7 +189,7 @@ impl Dynamic {
         match &self.0 {
             Union::Unit(_) => TypeId::of::<()>(),
             Union::Bool(_) => TypeId::of::<bool>(),
-            Union::Str(_) => TypeId::of::<String>(),
+            Union::Str(_) => TypeId::of::<ImmutableString>(),
             Union::Char(_) => TypeId::of::<char>(),
             Union::Int(_) => TypeId::of::<INT>(),
             #[cfg(not(feature = "no_float"))]
@@ -342,6 +346,12 @@ impl Dynamic {
             return Self(result);
         } else if let Some(result) = dyn_value.downcast_ref::<char>().cloned().map(Union::Char) {
             return Self(result);
+        } else if let Some(result) = dyn_value
+            .downcast_ref::<ImmutableString>()
+            .cloned()
+            .map(Union::Str)
+        {
+            return Self(result);
         }
 
         #[cfg(not(feature = "no_float"))]
@@ -358,7 +368,7 @@ impl Dynamic {
             Err(var) => var,
         };
         var = match unsafe_cast_box::<_, String>(var) {
-            Ok(s) => return Self(Union::Str(s)),
+            Ok(s) => return Self(Union::Str(s.into())),
             Err(var) => var,
         };
         #[cfg(not(feature = "no_index"))]
@@ -395,14 +405,19 @@ impl Dynamic {
     /// assert_eq!(x.try_cast::<u32>().unwrap(), 42);
     /// ```
     pub fn try_cast<T: Variant>(self) -> Option<T> {
-        if TypeId::of::<T>() == TypeId::of::<Dynamic>() {
+        let type_id = TypeId::of::<T>();
+
+        if type_id == TypeId::of::<Dynamic>() {
             return unsafe_cast_box::<_, T>(Box::new(self)).ok().map(|v| *v);
         }
 
         match self.0 {
             Union::Unit(value) => unsafe_try_cast(value),
             Union::Bool(value) => unsafe_try_cast(value),
-            Union::Str(value) => unsafe_cast_box::<_, T>(value).ok().map(|v| *v),
+            Union::Str(value) if type_id == TypeId::of::<ImmutableString>() => {
+                unsafe_try_cast(value)
+            }
+            Union::Str(value) => unsafe_try_cast(value.into_owned()),
             Union::Char(value) => unsafe_try_cast(value),
             Union::Int(value) => unsafe_try_cast(value),
             #[cfg(not(feature = "no_float"))]
@@ -434,16 +449,19 @@ impl Dynamic {
     /// assert_eq!(x.cast::<u32>(), 42);
     /// ```
     pub fn cast<T: Variant + Clone>(self) -> T {
-        //self.try_cast::<T>().unwrap()
+        let type_id = TypeId::of::<T>();
 
-        if TypeId::of::<T>() == TypeId::of::<Dynamic>() {
+        if type_id == TypeId::of::<Dynamic>() {
             return *unsafe_cast_box::<_, T>(Box::new(self)).unwrap();
         }
 
         match self.0 {
             Union::Unit(value) => unsafe_try_cast(value).unwrap(),
             Union::Bool(value) => unsafe_try_cast(value).unwrap(),
-            Union::Str(value) => *unsafe_cast_box::<_, T>(value).unwrap(),
+            Union::Str(value) if type_id == TypeId::of::<ImmutableString>() => {
+                unsafe_try_cast(value).unwrap()
+            }
+            Union::Str(value) => unsafe_try_cast(value.into_owned()).unwrap(),
             Union::Char(value) => unsafe_try_cast(value).unwrap(),
             Union::Int(value) => unsafe_try_cast(value).unwrap(),
             #[cfg(not(feature = "no_float"))]
@@ -469,7 +487,9 @@ impl Dynamic {
         match &self.0 {
             Union::Unit(value) => (value as &dyn Any).downcast_ref::<T>(),
             Union::Bool(value) => (value as &dyn Any).downcast_ref::<T>(),
-            Union::Str(value) => (value.as_ref() as &dyn Any).downcast_ref::<T>(),
+            Union::Str(value) => (value as &dyn Any)
+                .downcast_ref::<T>()
+                .or_else(|| (value.as_ref() as &dyn Any).downcast_ref::<T>()),
             Union::Char(value) => (value as &dyn Any).downcast_ref::<T>(),
             Union::Int(value) => (value as &dyn Any).downcast_ref::<T>(),
             #[cfg(not(feature = "no_float"))]
@@ -495,7 +515,7 @@ impl Dynamic {
         match &mut self.0 {
             Union::Unit(value) => (value as &mut dyn Any).downcast_mut::<T>(),
             Union::Bool(value) => (value as &mut dyn Any).downcast_mut::<T>(),
-            Union::Str(value) => (value.as_mut() as &mut dyn Any).downcast_mut::<T>(),
+            Union::Str(value) => (value as &mut dyn Any).downcast_mut::<T>(),
             Union::Char(value) => (value as &mut dyn Any).downcast_mut::<T>(),
             Union::Int(value) => (value as &mut dyn Any).downcast_mut::<T>(),
             #[cfg(not(feature = "no_float"))]
@@ -519,6 +539,16 @@ impl Dynamic {
         }
     }
 
+    /// Cast the `Dynamic` as the system floating-point type `FLOAT` and return it.
+    /// Returns the name of the actual type if the cast fails.
+    #[cfg(not(feature = "no_float"))]
+    pub fn as_float(&self) -> Result<FLOAT, &'static str> {
+        match self.0 {
+            Union::Float(n) => Ok(n),
+            _ => Err(self.type_name()),
+        }
+    }
+
     /// Cast the `Dynamic` as a `bool` and return it.
     /// Returns the name of the actual type if the cast fails.
     pub fn as_bool(&self) -> Result<bool, &'static str> {
@@ -550,7 +580,7 @@ impl Dynamic {
     /// Returns the name of the actual type if the cast fails.
     pub fn take_string(self) -> Result<String, &'static str> {
         match self.0 {
-            Union::Str(s) => Ok(*s),
+            Union::Str(s) => Ok(s.into_owned()),
             _ => Err(self.type_name()),
         }
     }
@@ -584,7 +614,12 @@ impl From<char> for Dynamic {
 }
 impl From<String> for Dynamic {
     fn from(value: String) -> Self {
-        Self(Union::Str(Box::new(value)))
+        Self(Union::Str(value.into()))
+    }
+}
+impl From<ImmutableString> for Dynamic {
+    fn from(value: ImmutableString) -> Self {
+        Self(Union::Str(value))
     }
 }
 #[cfg(not(feature = "no_index"))]
@@ -595,6 +630,14 @@ impl<T: Variant + Clone> From<Vec<T>> for Dynamic {
         )))
     }
 }
+#[cfg(not(feature = "no_index"))]
+impl<T: Variant + Clone> From<&[T]> for Dynamic {
+    fn from(value: &[T]) -> Self {
+        Self(Union::Array(Box::new(
+            value.iter().cloned().map(Dynamic::from).collect(),
+        )))
+    }
+}
 #[cfg(not(feature = "no_object"))]
 impl<T: Variant + Clone> From<HashMap<String, T>> for Dynamic {
     fn from(value: HashMap<String, T>) -> Self {

src/api.rs

@@ -4,9 +4,7 @@ use crate::any::{Dynamic, Variant};
 use crate::engine::{make_getter, make_setter, Engine, State, FUNC_INDEXER};
 use crate::error::ParseError;
 use crate::fn_call::FuncArgs;
-use crate::fn_native::{
-    IteratorCallback, ObjectGetCallback, ObjectIndexerCallback, ObjectSetCallback,
-};
+use crate::fn_native::{IteratorFn, SendSync};
 use crate::fn_register::RegisterFn;
 use crate::optimize::{optimize_into_ast, OptimizationLevel};
 use crate::parser::{parse, parse_global_expr, AST};
@@ -123,8 +121,8 @@ impl Engine {
 
     /// Register an iterator adapter for a type with the `Engine`.
     /// This is an advanced feature.
-    pub fn register_iterator<T: Variant + Clone, F: IteratorCallback>(&mut self, f: F) {
-        self.global_module.set_iter(TypeId::of::<T>(), Box::new(f));
+    pub fn register_iterator<T: Variant + Clone>(&mut self, f: IteratorFn) {
+        self.global_module.set_iter(TypeId::of::<T>(), f);
     }
 
     /// Register a getter function for a member of a registered type with the `Engine`.
@@ -164,11 +162,13 @@ impl Engine {
     /// # }
     /// ```
     #[cfg(not(feature = "no_object"))]
-    pub fn register_get<T, U, F>(&mut self, name: &str, callback: F)
-    where
+    pub fn register_get<T, U>(
+        &mut self,
+        name: &str,
+        callback: impl Fn(&mut T) -> U + SendSync + 'static,
+    ) where
         T: Variant + Clone,
         U: Variant + Clone,
-        F: ObjectGetCallback<T, U>,
     {
         self.register_fn(&make_getter(name), callback);
     }
@@ -210,11 +210,13 @@ impl Engine {
     /// # }
     /// ```
     #[cfg(not(feature = "no_object"))]
-    pub fn register_set<T, U, F>(&mut self, name: &str, callback: F)
-    where
+    pub fn register_set<T, U>(
+        &mut self,
+        name: &str,
+        callback: impl Fn(&mut T, U) + SendSync + 'static,
+    ) where
         T: Variant + Clone,
         U: Variant + Clone,
-        F: ObjectSetCallback<T, U>,
     {
         self.register_fn(&make_setter(name), callback);
     }
@@ -258,12 +260,14 @@ impl Engine {
     /// # }
     /// ```
     #[cfg(not(feature = "no_object"))]
-    pub fn register_get_set<T, U, G, S>(&mut self, name: &str, get_fn: G, set_fn: S)
-    where
+    pub fn register_get_set<T, U>(
+        &mut self,
+        name: &str,
+        get_fn: impl Fn(&mut T) -> U + SendSync + 'static,
+        set_fn: impl Fn(&mut T, U) + SendSync + 'static,
+    ) where
         T: Variant + Clone,
         U: Variant + Clone,
-        G: ObjectGetCallback<T, U>,
-        S: ObjectSetCallback<T, U>,
     {
         self.register_get(name, get_fn);
         self.register_set(name, set_fn);
@@ -307,12 +311,13 @@ impl Engine {
     /// ```
     #[cfg(not(feature = "no_object"))]
     #[cfg(not(feature = "no_index"))]
-    pub fn register_indexer<T, X, U, F>(&mut self, callback: F)
-    where
+    pub fn register_indexer<T, X, U>(
+        &mut self,
+        callback: impl Fn(&mut T, X) -> U + SendSync + 'static,
+    ) where
         T: Variant + Clone,
         U: Variant + Clone,
         X: Variant + Clone,
-        F: ObjectIndexerCallback<T, X, U>,
     {
         self.register_fn(FUNC_INDEXER, callback);
     }
@@ -336,7 +341,7 @@ impl Engine {
     /// # Ok(())
     /// # }
     /// ```
-    pub fn compile(&self, script: &str) -> Result<AST, Box<ParseError>> {
+    pub fn compile(&self, script: &str) -> Result<AST, ParseError> {
         self.compile_with_scope(&Scope::new(), script)
     }
 
@@ -378,7 +383,7 @@ impl Engine {
     /// # Ok(())
     /// # }
     /// ```
-    pub fn compile_with_scope(&self, scope: &Scope, script: &str) -> Result<AST, Box<ParseError>> {
+    pub fn compile_with_scope(&self, scope: &Scope, script: &str) -> Result<AST, ParseError> {
         self.compile_scripts_with_scope(scope, &[script])
     }
 
@@ -432,7 +437,7 @@ impl Engine {
         &self,
         scope: &Scope,
         scripts: &[&str],
-    ) -> Result<AST, Box<ParseError>> {
+    ) -> Result<AST, ParseError> {
         self.compile_with_scope_and_optimization_level(scope, scripts, self.optimization_level)
     }
 
@@ -442,9 +447,16 @@ impl Engine {
         scope: &Scope,
         scripts: &[&str],
         optimization_level: OptimizationLevel,
-    ) -> Result<AST, Box<ParseError>> {
+    ) -> Result<AST, ParseError> {
         let stream = lex(scripts);
-        parse(&mut stream.peekable(), self, scope, optimization_level)
+
+        parse(
+            &mut stream.peekable(),
+            self,
+            scope,
+            optimization_level,
+            (self.max_expr_depth, self.max_function_expr_depth),
+        )
     }
 
     /// Read the contents of a file into a string.
@@ -571,6 +583,7 @@ impl Engine {
             self,
             &scope,
             OptimizationLevel::None,
+            self.max_expr_depth,
         )?;
 
         // Handle null - map to ()
@@ -601,7 +614,7 @@ impl Engine {
     /// # Ok(())
     /// # }
     /// ```
-    pub fn compile_expression(&self, script: &str) -> Result<AST, Box<ParseError>> {
+    pub fn compile_expression(&self, script: &str) -> Result<AST, ParseError> {
         self.compile_expression_with_scope(&Scope::new(), script)
     }
 
@@ -648,13 +661,19 @@ impl Engine {
         &self,
         scope: &Scope,
         script: &str,
-    ) -> Result<AST, Box<ParseError>> {
+    ) -> Result<AST, ParseError> {
         let scripts = [script];
         let stream = lex(&scripts);
 
         {
             let mut peekable = stream.peekable();
-            parse_global_expr(&mut peekable, self, scope, self.optimization_level)
+            parse_global_expr(
+                &mut peekable,
+                self,
+                scope,
+                self.optimization_level,
+                self.max_expr_depth,
+            )
         }
     }
 
@@ -805,8 +824,15 @@ impl Engine {
     ) -> Result<T, Box<EvalAltResult>> {
         let scripts = [script];
         let stream = lex(&scripts);
-        // Since the AST will be thrown away afterwards, don't bother to optimize it
-        let ast = parse_global_expr(&mut stream.peekable(), self, scope, OptimizationLevel::None)?;
+
+        let ast = parse_global_expr(
+            &mut stream.peekable(),
+            self,
+            scope,
+            OptimizationLevel::None, // No need to optimize a lone expression
+            self.max_expr_depth,
+        )?;
+
         self.eval_ast_with_scope(scope, &ast)
     }
 
@@ -883,12 +909,12 @@ impl Engine {
         scope: &mut Scope,
         ast: &AST,
     ) -> Result<(Dynamic, u64), Box<EvalAltResult>> {
-        let mut state = State::new(ast.fn_lib());
+        let mut state = State::new();
 
         ast.statements()
             .iter()
             .try_fold(().into(), |_, stmt| {
-                self.eval_stmt(scope, &mut state, stmt, 0)
+                self.eval_stmt(scope, &mut state, ast.lib(), stmt, 0)
             })
             .or_else(|err| match *err {
                 EvalAltResult::Return(out, _) => Ok(out),
@@ -931,8 +957,13 @@ impl Engine {
         let scripts = [script];
         let stream = lex(&scripts);
 
-        // Since the AST will be thrown away afterwards, don't bother to optimize it
-        let ast = parse(&mut stream.peekable(), self, scope, OptimizationLevel::None)?;
+        let ast = parse(
+            &mut stream.peekable(),
+            self,
+            scope,
+            self.optimization_level,
+            (self.max_expr_depth, self.max_function_expr_depth),
+        )?;
         self.consume_ast_with_scope(scope, &ast)
     }
 
@@ -949,12 +980,12 @@ impl Engine {
         scope: &mut Scope,
         ast: &AST,
     ) -> Result<(), Box<EvalAltResult>> {
-        let mut state = State::new(ast.fn_lib());
+        let mut state = State::new();
 
         ast.statements()
             .iter()
             .try_fold(().into(), |_, stmt| {
-                self.eval_stmt(scope, &mut state, stmt, 0)
+                self.eval_stmt(scope, &mut state, ast.lib(), stmt, 0)
             })
             .map_or_else(
                 |err| match *err {
@@ -966,6 +997,7 @@ impl Engine {
     }
 
     /// Call a script function defined in an `AST` with multiple arguments.
+    /// Arguments are passed as a tuple.
     ///
     /// # Example
     ///
@@ -1009,29 +1041,81 @@ impl Engine {
         args: A,
     ) -> Result<T, Box<EvalAltResult>> {
         let mut arg_values = args.into_vec();
-        let mut args: StaticVec<_> = arg_values.iter_mut().collect();
-        let fn_lib = ast.fn_lib();
-        let pos = Position::none();
-
-        let fn_def = fn_lib
-            .get_function_by_signature(name, args.len(), true)
-            .ok_or_else(|| Box::new(EvalAltResult::ErrorFunctionNotFound(name.into(), pos)))?;
-
-        let state = State::new(fn_lib);
-        let args = args.as_mut();
-
-        let (result, _) = self.call_script_fn(Some(scope), state, name, fn_def, args, pos, 0)?;
+        let result = self.call_fn_dynamic(scope, ast, name, arg_values.as_mut())?;
 
         let return_type = self.map_type_name(result.type_name());
 
         return result.try_cast().ok_or_else(|| {
             Box::new(EvalAltResult::ErrorMismatchOutputType(
                 return_type.into(),
-                pos,
+                Position::none(),
             ))
         });
     }
 
+    /// Call a script function defined in an `AST` with multiple `Dynamic` arguments.
+    ///
+    /// ## WARNING
+    ///
+    /// All the arguments are _consumed_, meaning that they're replaced by `()`.
+    /// This is to avoid unnecessarily cloning the arguments.
+    /// Do you use the arguments after this call. If you need them afterwards,
+    /// clone them _before_ calling this function.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
+    /// # #[cfg(not(feature = "no_function"))]
+    /// # {
+    /// use rhai::{Engine, Scope};
+    ///
+    /// let engine = Engine::new();
+    ///
+    /// let ast = engine.compile(r"
+    ///     fn add(x, y) { len(x) + y + foo }
+    ///     fn add1(x)   { len(x) + 1 + foo }
+    ///     fn bar()     { foo/2 }
+    /// ")?;
+    ///
+    /// let mut scope = Scope::new();
+    /// scope.push("foo", 42_i64);
+    ///
+    /// // Call the script-defined function
+    /// let result = engine.call_fn_dynamic(&mut scope, &ast, "add", &mut [ String::from("abc").into(), 123_i64.into() ])?;
+    /// assert_eq!(result.cast::<i64>(), 168);
+    ///
+    /// let result = engine.call_fn_dynamic(&mut scope, &ast, "add1", &mut [ String::from("abc").into() ])?;
+    /// assert_eq!(result.cast::<i64>(), 46);
+    ///
+    /// let result= engine.call_fn_dynamic(&mut scope, &ast, "bar", &mut [])?;
+    /// assert_eq!(result.cast::<i64>(), 21);
+    /// # }
+    /// # Ok(())
+    /// # }
+    /// ```
+    #[cfg(not(feature = "no_function"))]
+    pub fn call_fn_dynamic(
+        &self,
+        scope: &mut Scope,
+        ast: &AST,
+        name: &str,
+        arg_values: &mut [Dynamic],
+    ) -> Result<Dynamic, Box<EvalAltResult>> {
+        let mut args: StaticVec<_> = arg_values.iter_mut().collect();
+        let lib = ast.lib();
+        let pos = Position::none();
+
+        let fn_def = lib
+            .get_function_by_signature(name, args.len(), true)
+            .ok_or_else(|| Box::new(EvalAltResult::ErrorFunctionNotFound(name.into(), pos)))?;
+
+        let mut state = State::new();
+        let args = args.as_mut();
+
+        self.call_script_fn(scope, &mut state, &lib, name, fn_def, args, pos, 0)
+    }
+
     /// Optimize the `AST` with constants defined in an external Scope.
     /// An optimized copy of the `AST` is returned while the original `AST` is consumed.
     ///
@@ -1050,14 +1134,14 @@ impl Engine {
         mut ast: AST,
         optimization_level: OptimizationLevel,
     ) -> AST {
-        let fn_lib = ast
-            .fn_lib()
+        let lib = ast
+            .lib()
             .iter()
             .map(|(_, fn_def)| fn_def.as_ref().clone())
             .collect();
 
         let stmt = mem::take(ast.statements_mut());
-        optimize_into_ast(self, scope, stmt, fn_lib, optimization_level)
+        optimize_into_ast(self, scope, stmt, lib, optimization_level)
     }
 
     /// Register a callback for script evaluation progress.
@@ -1094,47 +1178,7 @@ impl Engine {
     /// # Ok(())
     /// # }
     /// ```
-    #[cfg(feature = "sync")]
-    pub fn on_progress(&mut self, callback: impl Fn(u64) -> bool + Send + Sync + 'static) {
-        self.progress = Some(Box::new(callback));
-    }
-
-    /// Register a callback for script evaluation progress.
-    ///
-    /// # Example
-    ///
-    /// ```
-    /// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
-    /// # use std::cell::Cell;
-    /// # use std::rc::Rc;
-    /// use rhai::Engine;
-    ///
-    /// let result = Rc::new(Cell::new(0_u64));
-    /// let logger = result.clone();
-    ///
-    /// let mut engine = Engine::new();
-    ///
-    /// engine.on_progress(move |ops| {
-    ///     if ops > 10000 {
-    ///         false
-    ///     } else if ops % 800 == 0 {
-    ///         logger.set(ops);
-    ///         true
-    ///     } else {
-    ///         true
-    ///     }
-    /// });
-    ///
-    /// engine.consume("for x in range(0, 50000) {}")
-    ///     .expect_err("should error");
-    ///
-    /// assert_eq!(result.get(), 9600);
-    ///
-    /// # Ok(())
-    /// # }
-    /// ```
-    #[cfg(not(feature = "sync"))]
-    pub fn on_progress(&mut self, callback: impl Fn(u64) -> bool + 'static) {
+    pub fn on_progress(&mut self, callback: impl Fn(u64) -> bool + SendSync + 'static) {
         self.progress = Some(Box::new(callback));
     }
 
@@ -1162,36 +1206,7 @@ impl Engine {
     /// # Ok(())
     /// # }
     /// ```
-    #[cfg(feature = "sync")]
-    pub fn on_print(&mut self, callback: impl Fn(&str) + Send + Sync + 'static) {
-        self.print = Box::new(callback);
-    }
-    /// Override default action of `print` (print to stdout using `println!`)
-    ///
-    /// # Example
-    ///
-    /// ```
-    /// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
-    /// # use std::cell::RefCell;
-    /// # use std::rc::Rc;
-    /// use rhai::Engine;
-    ///
-    /// let result = Rc::new(RefCell::new(String::from("")));
-    ///
-    /// let mut engine = Engine::new();
-    ///
-    /// // Override action of 'print' function
-    /// let logger = result.clone();
-    /// engine.on_print(move |s| logger.borrow_mut().push_str(s));
-    ///
-    /// engine.consume("print(40 + 2);")?;
-    ///
-    /// assert_eq!(*result.borrow(), "42");
-    /// # Ok(())
-    /// # }
-    /// ```
-    #[cfg(not(feature = "sync"))]
-    pub fn on_print(&mut self, callback: impl Fn(&str) + 'static) {
+    pub fn on_print(&mut self, callback: impl Fn(&str) + SendSync + 'static) {
         self.print = Box::new(callback);
     }
 
@@ -1219,36 +1234,7 @@ impl Engine {
     /// # Ok(())
     /// # }
     /// ```
-    #[cfg(feature = "sync")]
-    pub fn on_debug(&mut self, callback: impl Fn(&str) + Send + Sync + 'static) {
-        self.debug = Box::new(callback);
-    }
-    /// Override default action of `debug` (print to stdout using `println!`)
-    ///
-    /// # Example
-    ///
-    /// ```
-    /// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
-    /// # use std::cell::RefCell;
-    /// # use std::rc::Rc;
-    /// use rhai::Engine;
-    ///
-    /// let result = Rc::new(RefCell::new(String::from("")));
-    ///
-    /// let mut engine = Engine::new();
-    ///
-    /// // Override action of 'print' function
-    /// let logger = result.clone();
-    /// engine.on_debug(move |s| logger.borrow_mut().push_str(s));
-    ///
-    /// engine.consume(r#"debug("hello");"#)?;
-    ///
-    /// assert_eq!(*result.borrow(), r#""hello""#);
-    /// # Ok(())
-    /// # }
-    /// ```
-    #[cfg(not(feature = "sync"))]
-    pub fn on_debug(&mut self, callback: impl Fn(&str) + 'static) {
+    pub fn on_debug(&mut self, callback: impl Fn(&str) + SendSync + 'static) {
         self.debug = Box::new(callback);
     }
 }

src/error.rs

@@ -110,20 +110,24 @@ pub enum ParseErrorType {
     AssignmentToCopy,
     /// Assignment to an a constant variable.
     AssignmentToConstant(String),
+    /// Expression exceeding the maximum levels of complexity.
+    ///
+    /// Never appears under the `unchecked` feature.
+    ExprTooDeep,
     /// Break statement not inside a loop.
     LoopBreak,
 }
 
 impl ParseErrorType {
     /// Make a `ParseError` using the current type and position.
-    pub(crate) fn into_err(self, pos: Position) -> Box<ParseError> {
-        Box::new(ParseError(self, pos))
+    pub(crate) fn into_err(self, pos: Position) -> ParseError {
+        ParseError(Box::new(self), pos)
     }
 }
 
 /// Error when parsing a script.
 #[derive(Debug, Eq, PartialEq, Clone, Hash)]
-pub struct ParseError(pub(crate) ParseErrorType, pub(crate) Position);
+pub struct ParseError(pub(crate) Box<ParseErrorType>, pub(crate) Position);
 
 impl ParseError {
     /// Get the parse error.
@@ -137,7 +141,7 @@ impl ParseError {
     }
 
     pub(crate) fn desc(&self) -> &str {
-        match &self.0 {
+        match self.0.as_ref() {
             ParseErrorType::BadInput(p) => p,
             ParseErrorType::UnexpectedEOF => "Script is incomplete",
             ParseErrorType::UnknownOperator(_) => "Unknown operator",
@@ -158,7 +162,8 @@ impl ParseError {
             ParseErrorType::DuplicatedExport(_) => "Duplicated variable/function in export statement",
             ParseErrorType::WrongExport => "Export statement can only appear at global level",
             ParseErrorType::AssignmentToCopy => "Only a copy of the value is change with this assignment",
-            ParseErrorType::AssignmentToConstant(_) => "Cannot assign to a constant value.",
+            ParseErrorType::AssignmentToConstant(_) => "Cannot assign to a constant value",
+            ParseErrorType::ExprTooDeep => "Expression exceeds maximum complexity",
             ParseErrorType::LoopBreak => "Break statement should only be used inside a loop"
         }
     }
@@ -168,7 +173,7 @@ impl Error for ParseError {}
 
 impl fmt::Display for ParseError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match &self.0 {
+        match self.0.as_ref() {
             ParseErrorType::BadInput(s) | ParseErrorType::MalformedCallExpr(s) => {
                 write!(f, "{}", if s.is_empty() { self.desc() } else { s })?
             }

src/fn_func.rs

@@ -80,7 +80,7 @@ pub trait Func<ARGS, RET> {
         self,
         script: &str,
         entry_point: &str,
-    ) -> Result<Self::Output, Box<ParseError>>;
+    ) -> Result<Self::Output, ParseError>;
 }
 
 macro_rules! def_anonymous_fn {
@@ -103,7 +103,7 @@ macro_rules! def_anonymous_fn {
                 })
             }
 
-            fn create_from_script(self, script: &str, entry_point: &str) -> Result<Self::Output, Box<ParseError>> {
+            fn create_from_script(self, script: &str, entry_point: &str) -> Result<Self::Output, ParseError> {
                 let ast = self.compile(script)?;
                 Ok(Func::<($($par,)*), RET>::create_from_ast(self, ast, entry_point))
             }

src/fn_native.rs

@@ -1,139 +1,144 @@
 use crate::any::Dynamic;
+use crate::parser::FnDef;
 use crate::result::EvalAltResult;
 
 use crate::stdlib::{boxed::Box, rc::Rc, sync::Arc};
 
+#[cfg(feature = "sync")]
+pub trait SendSync: Send + Sync {}
+#[cfg(feature = "sync")]
+impl<T: Send + Sync> SendSync for T {}
+
+#[cfg(not(feature = "sync"))]
+pub trait SendSync {}
+#[cfg(not(feature = "sync"))]
+impl<T> SendSync for T {}
+
+#[cfg(not(feature = "sync"))]
+pub type Shared<T> = Rc<T>;
+#[cfg(feature = "sync")]
+pub type Shared<T> = Arc<T>;
+
+/// Consume a `Shared` resource and return a mutable reference to the wrapped value.
+/// If the resource is shared (i.e. has other outstanding references), a cloned copy is used.
+pub fn shared_make_mut<T: Clone>(value: &mut Shared<T>) -> &mut T {
+    #[cfg(not(feature = "sync"))]
+    {
+        Rc::make_mut(value)
+    }
+    #[cfg(feature = "sync")]
+    {
+        Arc::make_mut(value)
+    }
+}
+
+/// Consume a `Shared` resource, assuming that it is unique (i.e. not shared).
+///
+/// # Panics
+///
+/// Panics if the resource is shared (i.e. has other outstanding references).
+pub fn shared_take<T: Clone>(value: Shared<T>) -> T {
+    #[cfg(not(feature = "sync"))]
+    {
+        Rc::try_unwrap(value).map_err(|_| ()).unwrap()
+    }
+    #[cfg(feature = "sync")]
+    {
+        Arc::try_unwrap(value).map_err(|_| ()).unwrap()
+    }
+}
+
 pub type FnCallArgs<'a> = [&'a mut Dynamic];
 
-#[cfg(feature = "sync")]
-pub type FnAny = dyn Fn(&mut FnCallArgs) -> Result<Dynamic, Box<EvalAltResult>> + Send + Sync;
 #[cfg(not(feature = "sync"))]
 pub type FnAny = dyn Fn(&mut FnCallArgs) -> Result<Dynamic, Box<EvalAltResult>>;
+#[cfg(feature = "sync")]
+pub type FnAny = dyn Fn(&mut FnCallArgs) -> Result<Dynamic, Box<EvalAltResult>> + Send + Sync;
 
-#[cfg(feature = "sync")]
-pub type IteratorFn = dyn Fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>> + Send + Sync;
-#[cfg(not(feature = "sync"))]
-pub type IteratorFn = dyn Fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>>;
+pub type IteratorFn = fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>>;
 
-#[cfg(feature = "sync")]
-pub type PrintCallback = dyn Fn(&str) + Send + Sync + 'static;
-#[cfg(not(feature = "sync"))]
-pub type PrintCallback = dyn Fn(&str) + 'static;
-
-#[cfg(feature = "sync")]
-pub type ProgressCallback = dyn Fn(u64) -> bool + Send + Sync + 'static;
-#[cfg(not(feature = "sync"))]
-pub type ProgressCallback = dyn Fn(u64) -> bool + 'static;
-
-// Define callback function types
-#[cfg(feature = "sync")]
-pub trait ObjectGetCallback<T, U>: Fn(&mut T) -> U + Send + Sync + 'static {}
-#[cfg(feature = "sync")]
-impl<F: Fn(&mut T) -> U + Send + Sync + 'static, T, U> ObjectGetCallback<T, U> for F {}
-
-#[cfg(not(feature = "sync"))]
-pub trait ObjectGetCallback<T, U>: Fn(&mut T) -> U + 'static {}
-#[cfg(not(feature = "sync"))]
-impl<F: Fn(&mut T) -> U + 'static, T, U> ObjectGetCallback<T, U> for F {}
-
-#[cfg(feature = "sync")]
-pub trait ObjectSetCallback<T, U>: Fn(&mut T, U) + Send + Sync + 'static {}
-#[cfg(feature = "sync")]
-impl<F: Fn(&mut T, U) + Send + Sync + 'static, T, U> ObjectSetCallback<T, U> for F {}
-
-#[cfg(not(feature = "sync"))]
-pub trait ObjectSetCallback<T, U>: Fn(&mut T, U) + 'static {}
-#[cfg(not(feature = "sync"))]
-impl<F: Fn(&mut T, U) + 'static, T, U> ObjectSetCallback<T, U> for F {}
-
-#[cfg(feature = "sync")]
-pub trait ObjectIndexerCallback<T, X, U>: Fn(&mut T, X) -> U + Send + Sync + 'static {}
-#[cfg(feature = "sync")]
-impl<F: Fn(&mut T, X) -> U + Send + Sync + 'static, T, X, U> ObjectIndexerCallback<T, X, U> for F {}
-
-#[cfg(not(feature = "sync"))]
-pub trait ObjectIndexerCallback<T, X, U>: Fn(&mut T, X) -> U + 'static {}
-#[cfg(not(feature = "sync"))]
-impl<F: Fn(&mut T, X) -> U + 'static, T, X, U> ObjectIndexerCallback<T, X, U> for F {}
-
-#[cfg(feature = "sync")]
-pub trait IteratorCallback:
-    Fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>> + Send + Sync + 'static
-{
-}
-#[cfg(feature = "sync")]
-impl<F: Fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>> + Send + Sync + 'static> IteratorCallback
-    for F
-{
+/// A type encapsulating a function callable by Rhai.
+#[derive(Clone)]
+pub enum CallableFunction {
+    /// A pure native Rust function with all arguments passed by value.
+    Pure(Shared<FnAny>),
+    /// A native Rust object method with the first argument passed by reference,
+    /// and the rest passed by value.
+    Method(Shared<FnAny>),
+    /// An iterator function.
+    Iterator(IteratorFn),
+    /// A script-defined function.
+    Script(Shared<FnDef>),
 }
 
-#[cfg(not(feature = "sync"))]
-pub trait IteratorCallback: Fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>> + 'static {}
-#[cfg(not(feature = "sync"))]
-impl<F: Fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>> + 'static> IteratorCallback for F {}
-
-/// A type representing the type of ABI of a native Rust function.
-#[derive(Debug, Eq, PartialEq, Clone, Copy, Hash)]
-pub enum NativeFunctionABI {
-    /// A pure function where all arguments are passed by value.
-    Pure,
-    /// An object method where the first argument is the object passed by mutable reference.
-    /// All other arguments are passed by value.
-    Method,
-}
-
-/// Trait implemented by all native Rust functions that are callable by Rhai.
-#[cfg(not(feature = "sync"))]
-pub trait NativeCallable {
-    /// Get the ABI type of a native Rust function.
-    fn abi(&self) -> NativeFunctionABI;
-    /// Call a native Rust function.
-    fn call(&self, args: &mut FnCallArgs) -> Result<Dynamic, Box<EvalAltResult>>;
-}
-
-/// Trait implemented by all native Rust functions that are callable by Rhai.
-#[cfg(feature = "sync")]
-pub trait NativeCallable: Send + Sync {
-    /// Get the ABI type of a native Rust function.
-    fn abi(&self) -> NativeFunctionABI;
-    /// Call a native Rust function.
-    fn call(&self, args: &mut FnCallArgs) -> Result<Dynamic, Box<EvalAltResult>>;
-}
-
-/// A type encapsulating a native Rust function callable by Rhai.
-pub struct NativeFunction(Box<FnAny>, NativeFunctionABI);
-
-impl NativeCallable for NativeFunction {
-    fn abi(&self) -> NativeFunctionABI {
-        self.1
+impl CallableFunction {
+    /// Is this a pure native Rust function?
+    pub fn is_pure(&self) -> bool {
+        match self {
+            Self::Pure(_) => true,
+            Self::Method(_) | Self::Iterator(_) | Self::Script(_) => false,
+        }
     }
-    fn call(&self, args: &mut FnCallArgs) -> Result<Dynamic, Box<EvalAltResult>> {
-        (self.0)(args)
+    /// Is this a pure native Rust method-call?
+    pub fn is_method(&self) -> bool {
+        match self {
+            Self::Method(_) => true,
+            Self::Pure(_) | Self::Iterator(_) | Self::Script(_) => false,
+        }
+    }
+    /// Is this an iterator function?
+    pub fn is_iter(&self) -> bool {
+        match self {
+            Self::Iterator(_) => true,
+            Self::Pure(_) | Self::Method(_) | Self::Script(_) => false,
+        }
+    }
+    /// Is this a Rhai-scripted function?
+    pub fn is_script(&self) -> bool {
+        match self {
+            Self::Script(_) => true,
+            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => false,
+        }
+    }
+    /// Get a reference to a native Rust function.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the `CallableFunction` is not `Pure` or `Method`.
+    pub fn get_native_fn(&self) -> &FnAny {
+        match self {
+            Self::Pure(f) | Self::Method(f) => f.as_ref(),
+            Self::Iterator(_) | Self::Script(_) => panic!(),
+        }
+    }
+    /// Get a reference to a script-defined function definition.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the `CallableFunction` is not `Script`.
+    pub fn get_fn_def(&self) -> &FnDef {
+        match self {
+            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => panic!(),
+            Self::Script(f) => f,
+        }
+    }
+    /// Get a reference to an iterator function.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the `CallableFunction` is not `Iterator`.
+    pub fn get_iter_fn(&self) -> IteratorFn {
+        match self {
+            Self::Iterator(f) => *f,
+            Self::Pure(_) | Self::Method(_) | Self::Script(_) => panic!(),
+        }
+    }
+    /// Create a new `CallableFunction::Pure`.
+    pub fn from_pure(func: Box<FnAny>) -> Self {
+        Self::Pure(func.into())
+    }
+    /// Create a new `CallableFunction::Method`.
+    pub fn from_method(func: Box<FnAny>) -> Self {
+        Self::Method(func.into())
     }
 }
-
-impl From<(Box<FnAny>, NativeFunctionABI)> for NativeFunction {
-    fn from(func: (Box<FnAny>, NativeFunctionABI)) -> Self {
-        Self::new(func.0, func.1)
-    }
-}
-impl NativeFunction {
-    /// Create a new `NativeFunction`.
-    pub fn new(func: Box<FnAny>, abi: NativeFunctionABI) -> Self {
-        Self(func, abi)
-    }
-}
-
-/// An external native Rust function.
-#[cfg(not(feature = "sync"))]
-pub type SharedNativeFunction = Rc<Box<dyn NativeCallable>>;
-/// An external native Rust function.
-#[cfg(feature = "sync")]
-pub type SharedNativeFunction = Arc<Box<dyn NativeCallable>>;
-
-/// A type iterator function.
-#[cfg(not(feature = "sync"))]
-pub type SharedIteratorFunction = Rc<Box<IteratorFn>>;
-/// An external native Rust function.
-#[cfg(feature = "sync")]
-pub type SharedIteratorFunction = Arc<Box<IteratorFn>>;

src/fn_register.rs

@@ -4,11 +4,11 @@
 
 use crate::any::{Dynamic, Variant};
 use crate::engine::Engine;
-use crate::fn_native::{FnCallArgs, NativeFunctionABI::*};
+use crate::fn_native::{CallableFunction, FnAny, FnCallArgs};
 use crate::parser::FnAccess;
 use crate::result::EvalAltResult;
 
-use crate::stdlib::{any::TypeId, boxed::Box, mem, string::ToString};
+use crate::stdlib::{any::TypeId, boxed::Box, mem};
 
 /// Trait to register custom functions with the `Engine`.
 pub trait RegisterFn<FN, ARGS, RET> {
@@ -42,49 +42,22 @@ pub trait RegisterFn<FN, ARGS, RET> {
     fn register_fn(&mut self, name: &str, f: FN);
 }
 
-/// Trait to register custom functions that return `Dynamic` values with the `Engine`.
-pub trait RegisterDynamicFn<FN, ARGS> {
-    /// Register a custom function returning `Dynamic` values with the `Engine`.
-    ///
-    /// # Example
-    ///
-    /// ```
-    /// # fn main() -> Result<(), Box<rhai::EvalAltResult>> {
-    /// use rhai::{Engine, Dynamic, RegisterDynamicFn};
-    ///
-    /// // Function that returns a Dynamic value
-    /// fn return_the_same_as_dynamic(x: i64) -> Dynamic {
-    ///     Dynamic::from(x)
-    /// }
-    ///
-    /// let mut engine = Engine::new();
-    ///
-    /// // You must use the trait rhai::RegisterDynamicFn to get this method.
-    /// engine.register_dynamic_fn("get_any_number", return_the_same_as_dynamic);
-    ///
-    /// assert_eq!(engine.eval::<i64>("get_any_number(42)")?, 42);
-    /// # Ok(())
-    /// # }
-    /// ```
-    fn register_dynamic_fn(&mut self, name: &str, f: FN);
-}
-
-/// Trait to register fallible custom functions returning `Result<_, Box<EvalAltResult>>` with the `Engine`.
-pub trait RegisterResultFn<FN, ARGS, RET> {
+/// Trait to register fallible custom functions returning `Result<Dynamic, Box<EvalAltResult>>` with the `Engine`.
+pub trait RegisterResultFn<FN, ARGS> {
     /// Register a custom fallible function with the `Engine`.
     ///
     /// # Example
     ///
     /// ```
-    /// use rhai::{Engine, RegisterResultFn, EvalAltResult};
+    /// use rhai::{Engine, Dynamic, RegisterResultFn, EvalAltResult};
     ///
     /// // Normal function
-    /// fn div(x: i64, y: i64) -> Result<i64, Box<EvalAltResult>> {
+    /// fn div(x: i64, y: i64) -> Result<Dynamic, Box<EvalAltResult>> {
     ///     if y == 0 {
     ///         // '.into()' automatically converts to 'Box<EvalAltResult::ErrorRuntime>'
     ///         Err("division by zero!".into())
     ///     } else {
-    ///         Ok(x / y)
+    ///         Ok((x / y).into())
     ///     }
     /// }
     ///
@@ -155,7 +128,7 @@ macro_rules! make_func {
 
             // Map the result
             $map(r)
-		})
+		}) as Box<FnAny>
 	};
 }
 
@@ -167,28 +140,22 @@ pub fn map_dynamic<T: Variant + Clone>(data: T) -> Result<Dynamic, Box<EvalAltRe
 
 /// To Dynamic mapping function.
 #[inline(always)]
-pub fn map_identity(data: Dynamic) -> Result<Dynamic, Box<EvalAltResult>> {
-    Ok(data)
-}
-
-/// To `Result<Dynamic, Box<EvalAltResult>>` mapping function.
-#[inline(always)]
-pub fn map_result<T: Variant + Clone>(
-    data: Result<T, Box<EvalAltResult>>,
+pub fn map_result(
+    data: Result<Dynamic, Box<EvalAltResult>>,
 ) -> Result<Dynamic, Box<EvalAltResult>> {
-    data.map(|v| v.into_dynamic())
+    data
 }
 
 macro_rules! def_register {
     () => {
-        def_register!(imp Pure;);
+        def_register!(imp from_pure :);
     };
-    (imp $abi:expr ; $($par:ident => $mark:ty => $param:ty => $clone:expr),*) => {
+    (imp $abi:ident : $($par:ident => $mark:ty => $param:ty => $clone:expr),*) => {
     //   ^ function ABI type
-    //                 ^ function parameter generic type name (A, B, C etc.)
-    //                               ^ function parameter marker type (T, Ref<T> or Mut<T>)
-    //                                           ^ function parameter actual type (T, &T or &mut T)
-    //                                                        ^ dereferencing function
+    //                  ^ function parameter generic type name (A, B, C etc.)
+    //                                ^ function parameter marker type (T, Ref<T> or Mut<T>)
+    //                                            ^ function parameter actual type (T, &T or &mut T)
+    //                                                         ^ dereferencing function
         impl<
             $($par: Variant + Clone,)*
 
@@ -202,9 +169,9 @@ macro_rules! def_register {
         > RegisterFn<FN, ($($mark,)*), RET> for Engine
         {
             fn register_fn(&mut self, name: &str, f: FN) {
-                self.global_module.set_fn(name.to_string(), $abi, FnAccess::Public,
+                self.global_module.set_fn(name, FnAccess::Public,
                     &[$(TypeId::of::<$par>()),*],
-                    make_func!(f : map_dynamic ; $($par => $clone),*)
+                    CallableFunction::$abi(make_func!(f : map_dynamic ; $($par => $clone),*))
                 );
             }
         }
@@ -213,35 +180,15 @@ macro_rules! def_register {
             $($par: Variant + Clone,)*
 
             #[cfg(feature = "sync")]
-            FN: Fn($($param),*) -> Dynamic + Send + Sync + 'static,
-
+            FN: Fn($($param),*) -> Result<Dynamic, Box<EvalAltResult>> + Send + Sync + 'static,
             #[cfg(not(feature = "sync"))]
-            FN: Fn($($param),*) -> Dynamic + 'static,
-        > RegisterDynamicFn<FN, ($($mark,)*)> for Engine
-        {
-            fn register_dynamic_fn(&mut self, name: &str, f: FN) {
-                self.global_module.set_fn(name.to_string(), $abi, FnAccess::Public,
-                    &[$(TypeId::of::<$par>()),*],
-                    make_func!(f : map_identity ; $($par => $clone),*)
-                );
-            }
-        }
-
-        impl<
-            $($par: Variant + Clone,)*
-
-            #[cfg(feature = "sync")]
-            FN: Fn($($param),*) -> Result<RET, Box<EvalAltResult>> + Send + Sync + 'static,
-            #[cfg(not(feature = "sync"))]
-            FN: Fn($($param),*) -> Result<RET, Box<EvalAltResult>> + 'static,
-
-            RET: Variant + Clone
-        > RegisterResultFn<FN, ($($mark,)*), RET> for Engine
+            FN: Fn($($param),*) -> Result<Dynamic, Box<EvalAltResult>> + 'static,
+        > RegisterResultFn<FN, ($($mark,)*)> for Engine
         {
             fn register_result_fn(&mut self, name: &str, f: FN) {
-                self.global_module.set_fn(name.to_string(), $abi, FnAccess::Public,
+                self.global_module.set_fn(name, FnAccess::Public,
                     &[$(TypeId::of::<$par>()),*],
-                    make_func!(f : map_result ; $($par => $clone),*)
+                    CallableFunction::$abi(make_func!(f : map_result ; $($par => $clone),*))
                 );
             }
         }
@@ -249,10 +196,11 @@ macro_rules! def_register {
         //def_register!(imp_pop $($par => $mark => $param),*);
     };
     ($p0:ident $(, $p:ident)*) => {
-        def_register!(imp Pure   ; $p0 => $p0      => $p0      => by_value $(, $p => $p => $p => by_value)*);
-        def_register!(imp Method ; $p0 => Mut<$p0> => &mut $p0 => by_ref   $(, $p => $p => $p => by_value)*);
-        // handle the first parameter                             ^ first parameter passed through
-        //                                                                                       ^ others passed by value (by_value)
+        def_register!(imp from_pure   : $p0 => $p0      => $p0      => by_value $(, $p => $p => $p => by_value)*);
+        def_register!(imp from_method : $p0 => Mut<$p0> => &mut $p0 => by_ref   $(, $p => $p => $p => by_value)*);
+        //                ^ CallableFunction
+        // handle the first parameter                                  ^ first parameter passed through
+        //                                                                                            ^ others passed by value (by_value)
 
         // Currently does not support first argument which is a reference, as there will be
         // conflicting implementations since &T: Any and T: Any cannot be distinguished

src/lib.rs

@@ -49,18 +49,18 @@
 //!
 //! ## Optional features
 //!
-//! | Feature       | Description                                                                                                                                              |
-//! | ------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- |
-//! | `unchecked`   | Exclude arithmetic checking (such as overflows and division by zero). Beware that a bad script may panic the entire system!                              |
-//! | `no_function` | Disable script-defined functions if not needed.                                                                                                          |
-//! | `no_index`    | Disable arrays and indexing features if not needed.                                                                                                      |
-//! | `no_object`   | Disable support for custom types and objects.                                                                                                            |
-//! | `no_float`    | Disable floating-point numbers and math if not needed.                                                                                                   |
-//! | `no_optimize` | Disable the script optimizer.                                                                                                                            |
-//! | `only_i32`    | Set the system integer type to `i32` and disable all other integer types. `INT` is set to `i32`.                                                         |
-//! | `only_i64`    | Set the system integer type to `i64` and disable all other integer types. `INT` is set to `i64`.                                                         |
-//! | `no_std`      | Build for `no-std`. Notice that additional dependencies will be pulled in to replace `std` features.                                                     |
-//! | `sync`        | Restrict all values types to those that are `Send + Sync`. Under this feature, `Engine`, `Scope` and `AST` are all `Send + Sync`.                        |
+//! | Feature       | Description                                                                                                                       |
+//! | ------------- | ----------------------------------------------------------------------------------------------------------------------------------|
+//! | `unchecked`   | Exclude arithmetic checking (such as overflows and division by zero). Beware that a bad script may panic the entire system!       |
+//! | `no_function` | Disable script-defined functions if not needed.                                                                                   |
+//! | `no_index`    | Disable arrays and indexing features if not needed.                                                                               |
+//! | `no_object`   | Disable support for custom types and objects.                                                                                     |
+//! | `no_float`    | Disable floating-point numbers and math if not needed.                                                                            |
+//! | `no_optimize` | Disable the script optimizer.                                                                                                     |
+//! | `only_i32`    | Set the system integer type to `i32` and disable all other integer types. `INT` is set to `i32`.                                  |
+//! | `only_i64`    | Set the system integer type to `i64` and disable all other integer types. `INT` is set to `i64`.                                  |
+//! | `no_std`      | Build for `no-std`. Notice that additional dependencies will be pulled in to replace `std` features.                              |
+//! | `sync`        | Restrict all values types to those that are `Send + Sync`. Under this feature, `Engine`, `Scope` and `AST` are all `Send + Sync`. |
 //!
 //! [Check out the README on GitHub for details on the Rhai language!](https://github.com/jonathandturner/rhai)
 
@@ -91,10 +91,9 @@ mod utils;
 pub use any::Dynamic;
 pub use engine::Engine;
 pub use error::{ParseError, ParseErrorType};
-pub use fn_native::NativeCallable;
-pub use fn_register::{RegisterDynamicFn, RegisterFn, RegisterResultFn};
+pub use fn_register::{RegisterFn, RegisterResultFn};
 pub use module::Module;
-pub use parser::{AST, INT};
+pub use parser::{ImmutableString, AST, INT};
 pub use result::EvalAltResult;
 pub use scope::Scope;
 pub use token::Position;

src/module.rs

@@ -2,36 +2,32 @@
 
 use crate::any::{Dynamic, Variant};
 use crate::calc_fn_hash;
-use crate::engine::{Engine, FunctionsLib};
-use crate::fn_native::{
-    FnAny, FnCallArgs, IteratorFn, NativeCallable, NativeFunction, NativeFunctionABI,
-    NativeFunctionABI::*, SharedIteratorFunction, SharedNativeFunction,
+use crate::engine::{make_getter, make_setter, Engine, FunctionsLib, FUNC_INDEXER};
+use crate::fn_native::{CallableFunction, FnCallArgs, IteratorFn};
+use crate::parser::{
+    FnAccess,
+    FnAccess::{Private, Public},
+    AST,
 };
-use crate::parser::{FnAccess, FnDef, SharedFnDef, AST};
 use crate::result::EvalAltResult;
 use crate::scope::{Entry as ScopeEntry, EntryType as ScopeEntryType, Scope};
 use crate::token::{Position, Token};
-use crate::utils::{StaticVec, EMPTY_TYPE_ID};
+use crate::utils::{StaticVec, StraightHasherBuilder};
 
 use crate::stdlib::{
     any::TypeId,
     boxed::Box,
     collections::HashMap,
     fmt,
-    iter::{empty, repeat},
+    iter::empty,
     mem,
     num::NonZeroUsize,
     ops::{Deref, DerefMut},
-    rc::Rc,
     string::{String, ToString},
-    sync::Arc,
     vec,
     vec::Vec,
 };
 
-/// Default function access mode.
-const DEF_ACCESS: FnAccess = FnAccess::Public;
-
 /// Return type of module-level Rust function.
 pub type FuncReturn<T> = Result<T, Box<EvalAltResult>>;
 
@@ -48,22 +44,24 @@ pub struct Module {
     variables: HashMap<String, Dynamic>,
 
     /// Flattened collection of all module variables, including those in sub-modules.
-    all_variables: HashMap<u64, Dynamic>,
+    all_variables: HashMap<u64, Dynamic, StraightHasherBuilder>,
 
     /// External Rust functions.
-    functions: HashMap<u64, (String, FnAccess, StaticVec<TypeId>, SharedNativeFunction)>,
-
-    /// Flattened collection of all external Rust functions, including those in sub-modules.
-    all_functions: HashMap<u64, SharedNativeFunction>,
+    functions: HashMap<
+        u64,
+        (String, FnAccess, StaticVec<TypeId>, CallableFunction),
+        StraightHasherBuilder,
+    >,
 
     /// Script-defined functions.
-    fn_lib: FunctionsLib,
-
-    /// Flattened collection of all script-defined functions, including those in sub-modules.
-    all_fn_lib: FunctionsLib,
+    lib: FunctionsLib,
 
     /// Iterator functions, keyed by the type producing the iterator.
-    type_iterators: HashMap<TypeId, SharedIteratorFunction>,
+    type_iterators: HashMap<TypeId, IteratorFn>,
+
+    /// Flattened collection of all external Rust functions, native or scripted,
+    /// including those in sub-modules.
+    all_functions: HashMap<u64, CallableFunction, StraightHasherBuilder>,
 }
 
 impl fmt::Debug for Module {
@@ -73,7 +71,7 @@ impl fmt::Debug for Module {
             "<module {:?}, functions={}, lib={}>",
             self.variables,
             self.functions.len(),
-            self.fn_lib.len()
+            self.lib.len()
         )
     }
 }
@@ -107,7 +105,7 @@ impl Module {
     /// ```
     pub fn new_with_capacity(capacity: usize) -> Self {
         Self {
-            functions: HashMap::with_capacity(capacity),
+            functions: HashMap::with_capacity_and_hasher(capacity, StraightHasherBuilder),
             ..Default::default()
         }
     }
@@ -170,7 +168,7 @@ impl Module {
     /// module.set_var("answer", 42_i64);
     /// assert_eq!(module.get_var_value::<i64>("answer").unwrap(), 42);
     /// ```
-    pub fn set_var<K: Into<String>, T: Variant + Clone>(&mut self, name: K, value: T) {
+    pub fn set_var(&mut self, name: impl Into<String>, value: impl Variant + Clone) {
         self.variables.insert(name.into(), Dynamic::from(value));
     }
 
@@ -250,7 +248,7 @@ impl Module {
     /// module.set_sub_module("question", sub_module);
     /// assert!(module.get_sub_module("question").is_some());
     /// ```
-    pub fn set_sub_module<K: Into<String>>(&mut self, name: K, sub_module: Module) {
+    pub fn set_sub_module(&mut self, name: impl Into<String>, sub_module: Module) {
         self.modules.insert(name.into(), sub_module.into());
     }
 
@@ -277,24 +275,19 @@ impl Module {
     /// If there is an existing Rust function of the same hash, it is replaced.
     pub fn set_fn(
         &mut self,
-        name: String,
-        abi: NativeFunctionABI,
+        name: impl Into<String>,
         access: FnAccess,
         params: &[TypeId],
-        func: Box<FnAny>,
+        func: CallableFunction,
     ) -> u64 {
-        let hash_fn = calc_fn_hash(empty(), &name, params.iter().cloned());
+        let name = name.into();
 
-        let f = Box::new(NativeFunction::from((func, abi))) as Box<dyn NativeCallable>;
-
-        #[cfg(not(feature = "sync"))]
-        let func = Rc::new(f);
-        #[cfg(feature = "sync")]
-        let func = Arc::new(f);
+        let hash_fn = calc_fn_hash(empty(), &name, params.len(), params.iter().cloned());
 
         let params = params.into_iter().cloned().collect();
 
-        self.functions.insert(hash_fn, (name, access, params, func));
+        self.functions
+            .insert(hash_fn, (name, access, params, func.into()));
 
         hash_fn
     }
@@ -312,15 +305,20 @@ impl Module {
     /// let hash = module.set_fn_0("calc", || Ok(42_i64));
     /// assert!(module.get_fn(hash).is_some());
     /// ```
-    pub fn set_fn_0<K: Into<String>, T: Variant + Clone>(
+    pub fn set_fn_0<T: Variant + Clone>(
         &mut self,
-        name: K,
+        name: impl Into<String>,
         #[cfg(not(feature = "sync"))] func: impl Fn() -> FuncReturn<T> + 'static,
         #[cfg(feature = "sync")] func: impl Fn() -> FuncReturn<T> + Send + Sync + 'static,
     ) -> u64 {
         let f = move |_: &mut FnCallArgs| func().map(Dynamic::from);
-        let arg_types = [];
-        self.set_fn(name.into(), Pure, DEF_ACCESS, &arg_types, Box::new(f))
+        let args = [];
+        self.set_fn(
+            name,
+            Public,
+            &args,
+            CallableFunction::from_pure(Box::new(f)),
+        )
     }
 
     /// Set a Rust function taking one parameter into the module, returning a hash key.
@@ -336,16 +334,21 @@ impl Module {
     /// let hash = module.set_fn_1("calc", |x: i64| Ok(x + 1));
     /// assert!(module.get_fn(hash).is_some());
     /// ```
-    pub fn set_fn_1<K: Into<String>, A: Variant + Clone, T: Variant + Clone>(
+    pub fn set_fn_1<A: Variant + Clone, T: Variant + Clone>(
         &mut self,
-        name: K,
+        name: impl Into<String>,
         #[cfg(not(feature = "sync"))] func: impl Fn(A) -> FuncReturn<T> + 'static,
         #[cfg(feature = "sync")] func: impl Fn(A) -> FuncReturn<T> + Send + Sync + 'static,
     ) -> u64 {
         let f =
             move |args: &mut FnCallArgs| func(mem::take(args[0]).cast::<A>()).map(Dynamic::from);
-        let arg_types = [TypeId::of::<A>()];
-        self.set_fn(name.into(), Pure, DEF_ACCESS, &arg_types, Box::new(f))
+        let args = [TypeId::of::<A>()];
+        self.set_fn(
+            name,
+            Public,
+            &args,
+            CallableFunction::from_pure(Box::new(f)),
+        )
     }
 
     /// Set a Rust function taking one mutable parameter into the module, returning a hash key.
@@ -361,17 +364,45 @@ impl Module {
     /// let hash = module.set_fn_1_mut("calc", |x: &mut i64| { *x += 1; Ok(*x) });
     /// assert!(module.get_fn(hash).is_some());
     /// ```
-    pub fn set_fn_1_mut<K: Into<String>, A: Variant + Clone, T: Variant + Clone>(
+    pub fn set_fn_1_mut<A: Variant + Clone, T: Variant + Clone>(
         &mut self,
-        name: K,
+        name: impl Into<String>,
         #[cfg(not(feature = "sync"))] func: impl Fn(&mut A) -> FuncReturn<T> + 'static,
         #[cfg(feature = "sync")] func: impl Fn(&mut A) -> FuncReturn<T> + Send + Sync + 'static,
     ) -> u64 {
         let f = move |args: &mut FnCallArgs| {
             func(args[0].downcast_mut::<A>().unwrap()).map(Dynamic::from)
         };
-        let arg_types = [TypeId::of::<A>()];
-        self.set_fn(name.into(), Method, DEF_ACCESS, &arg_types, Box::new(f))
+        let args = [TypeId::of::<A>()];
+        self.set_fn(
+            name,
+            Public,
+            &args,
+            CallableFunction::from_method(Box::new(f)),
+        )
+    }
+
+    /// Set a Rust getter function taking one mutable parameter, returning a hash key.
+    ///
+    /// If there is a similar existing Rust getter function, it is replaced.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rhai::Module;
+    ///
+    /// let mut module = Module::new();
+    /// let hash = module.set_getter_fn("value", |x: &mut i64| { Ok(*x) });
+    /// assert!(module.get_fn(hash).is_some());
+    /// ```
+    #[cfg(not(feature = "no_object"))]
+    pub fn set_getter_fn<A: Variant + Clone, T: Variant + Clone>(
+        &mut self,
+        name: impl Into<String>,
+        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A) -> FuncReturn<T> + 'static,
+        #[cfg(feature = "sync")] func: impl Fn(&mut A) -> FuncReturn<T> + Send + Sync + 'static,
+    ) -> u64 {
+        self.set_fn_1_mut(make_getter(&name.into()), func)
     }
 
     /// Set a Rust function taking two parameters into the module, returning a hash key.
@@ -381,17 +412,17 @@ impl Module {
     /// # Examples
     ///
     /// ```
-    /// use rhai::Module;
+    /// use rhai::{Module, ImmutableString};
     ///
     /// let mut module = Module::new();
-    /// let hash = module.set_fn_2("calc", |x: i64, y: String| {
+    /// let hash = module.set_fn_2("calc", |x: i64, y: ImmutableString| {
     ///     Ok(x + y.len() as i64)
     /// });
     /// assert!(module.get_fn(hash).is_some());
     /// ```
-    pub fn set_fn_2<K: Into<String>, A: Variant + Clone, B: Variant + Clone, T: Variant + Clone>(
+    pub fn set_fn_2<A: Variant + Clone, B: Variant + Clone, T: Variant + Clone>(
         &mut self,
-        name: K,
+        name: impl Into<String>,
         #[cfg(not(feature = "sync"))] func: impl Fn(A, B) -> FuncReturn<T> + 'static,
         #[cfg(feature = "sync")] func: impl Fn(A, B) -> FuncReturn<T> + Send + Sync + 'static,
     ) -> u64 {
@@ -401,32 +432,34 @@ impl Module {
 
             func(a, b).map(Dynamic::from)
         };
-        let arg_types = [TypeId::of::<A>(), TypeId::of::<B>()];
-        self.set_fn(name.into(), Pure, DEF_ACCESS, &arg_types, Box::new(f))
+        let args = [TypeId::of::<A>(), TypeId::of::<B>()];
+        self.set_fn(
+            name,
+            Public,
+            &args,
+            CallableFunction::from_pure(Box::new(f)),
+        )
     }
 
     /// Set a Rust function taking two parameters (the first one mutable) into the module,
     /// returning a hash key.
     ///
+    /// If there is a similar existing Rust function, it is replaced.
+    ///
     /// # Examples
     ///
     /// ```
-    /// use rhai::Module;
+    /// use rhai::{Module, ImmutableString};
     ///
     /// let mut module = Module::new();
-    /// let hash = module.set_fn_2_mut("calc", |x: &mut i64, y: String| {
+    /// let hash = module.set_fn_2_mut("calc", |x: &mut i64, y: ImmutableString| {
     ///     *x += y.len() as i64; Ok(*x)
     /// });
     /// assert!(module.get_fn(hash).is_some());
     /// ```
-    pub fn set_fn_2_mut<
-        K: Into<String>,
-        A: Variant + Clone,
-        B: Variant + Clone,
-        T: Variant + Clone,
-    >(
+    pub fn set_fn_2_mut<A: Variant + Clone, B: Variant + Clone, T: Variant + Clone>(
         &mut self,
-        name: K,
+        name: impl Into<String>,
         #[cfg(not(feature = "sync"))] func: impl Fn(&mut A, B) -> FuncReturn<T> + 'static,
         #[cfg(feature = "sync")] func: impl Fn(&mut A, B) -> FuncReturn<T> + Send + Sync + 'static,
     ) -> u64 {
@@ -436,8 +469,66 @@ impl Module {
 
             func(a, b).map(Dynamic::from)
         };
-        let arg_types = [TypeId::of::<A>(), TypeId::of::<B>()];
-        self.set_fn(name.into(), Method, DEF_ACCESS, &arg_types, Box::new(f))
+        let args = [TypeId::of::<A>(), TypeId::of::<B>()];
+        self.set_fn(
+            name,
+            Public,
+            &args,
+            CallableFunction::from_method(Box::new(f)),
+        )
+    }
+
+    /// Set a Rust setter function taking two parameters (the first one mutable) into the module,
+    /// returning a hash key.
+    ///
+    /// If there is a similar existing setter Rust function, it is replaced.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rhai::{Module, ImmutableString};
+    ///
+    /// let mut module = Module::new();
+    /// let hash = module.set_setter_fn("value", |x: &mut i64, y: ImmutableString| {
+    ///     *x = y.len() as i64;
+    ///     Ok(())
+    /// });
+    /// assert!(module.get_fn(hash).is_some());
+    /// ```
+    #[cfg(not(feature = "no_object"))]
+    pub fn set_setter_fn<A: Variant + Clone, B: Variant + Clone>(
+        &mut self,
+        name: impl Into<String>,
+        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A, B) -> FuncReturn<()> + 'static,
+        #[cfg(feature = "sync")] func: impl Fn(&mut A, B) -> FuncReturn<()> + Send + Sync + 'static,
+    ) -> u64 {
+        self.set_fn_2_mut(make_setter(&name.into()), func)
+    }
+
+    /// Set a Rust indexer function taking two parameters (the first one mutable) into the module,
+    /// returning a hash key.
+    ///
+    /// If there is a similar existing setter Rust function, it is replaced.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rhai::{Module, ImmutableString};
+    ///
+    /// let mut module = Module::new();
+    /// let hash = module.set_indexer_fn(|x: &mut i64, y: ImmutableString| {
+    ///     Ok(*x + y.len() as i64)
+    /// });
+    /// assert!(module.get_fn(hash).is_some());
+    /// ```
+    #[cfg(not(feature = "no_object"))]
+    #[cfg(not(feature = "no_index"))]
+    pub fn set_indexer_fn<A: Variant + Clone, B: Variant + Clone, T: Variant + Clone>(
+        &mut self,
+        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A, B) -> FuncReturn<T> + 'static,
+        #[cfg(feature = "sync")] func: impl Fn(&mut A, B) -> FuncReturn<T> + Send + Sync + 'static,
+    ) -> u64 {
+        self.set_fn_2_mut(FUNC_INDEXER, func)
     }
 
     /// Set a Rust function taking three parameters into the module, returning a hash key.
@@ -447,23 +538,22 @@ impl Module {
     /// # Examples
     ///
     /// ```
-    /// use rhai::Module;
+    /// use rhai::{Module, ImmutableString};
     ///
     /// let mut module = Module::new();
-    /// let hash = module.set_fn_3("calc", |x: i64, y: String, z: i64| {
+    /// let hash = module.set_fn_3("calc", |x: i64, y: ImmutableString, z: i64| {
     ///     Ok(x + y.len() as i64 + z)
     /// });
     /// assert!(module.get_fn(hash).is_some());
     /// ```
     pub fn set_fn_3<
-        K: Into<String>,
         A: Variant + Clone,
         B: Variant + Clone,
         C: Variant + Clone,
         T: Variant + Clone,
     >(
         &mut self,
-        name: K,
+        name: impl Into<String>,
         #[cfg(not(feature = "sync"))] func: impl Fn(A, B, C) -> FuncReturn<T> + 'static,
         #[cfg(feature = "sync")] func: impl Fn(A, B, C) -> FuncReturn<T> + Send + Sync + 'static,
     ) -> u64 {
@@ -474,8 +564,13 @@ impl Module {
 
             func(a, b, c).map(Dynamic::from)
         };
-        let arg_types = [TypeId::of::<A>(), TypeId::of::<B>(), TypeId::of::<C>()];
-        self.set_fn(name.into(), Pure, DEF_ACCESS, &arg_types, Box::new(f))
+        let args = [TypeId::of::<A>(), TypeId::of::<B>(), TypeId::of::<C>()];
+        self.set_fn(
+            name,
+            Public,
+            &args,
+            CallableFunction::from_pure(Box::new(f)),
+        )
     }
 
     /// Set a Rust function taking three parameters (the first one mutable) into the module,
@@ -486,23 +581,22 @@ impl Module {
     /// # Examples
     ///
     /// ```
-    /// use rhai::Module;
+    /// use rhai::{Module, ImmutableString};
     ///
     /// let mut module = Module::new();
-    /// let hash = module.set_fn_3_mut("calc", |x: &mut i64, y: String, z: i64| {
+    /// let hash = module.set_fn_3_mut("calc", |x: &mut i64, y: ImmutableString, z: i64| {
     ///     *x += y.len() as i64 + z; Ok(*x)
     /// });
     /// assert!(module.get_fn(hash).is_some());
     /// ```
     pub fn set_fn_3_mut<
-        K: Into<String>,
         A: Variant + Clone,
         B: Variant + Clone,
         C: Variant + Clone,
         T: Variant + Clone,
     >(
         &mut self,
-        name: K,
+        name: impl Into<String>,
         #[cfg(not(feature = "sync"))] func: impl Fn(&mut A, B, C) -> FuncReturn<T> + 'static,
         #[cfg(feature = "sync")] func: impl Fn(&mut A, B, C) -> FuncReturn<T> + Send + Sync + 'static,
     ) -> u64 {
@@ -513,8 +607,112 @@ impl Module {
 
             func(a, b, c).map(Dynamic::from)
         };
-        let arg_types = [TypeId::of::<A>(), TypeId::of::<B>(), TypeId::of::<C>()];
-        self.set_fn(name.into(), Method, DEF_ACCESS, &arg_types, Box::new(f))
+        let args = [TypeId::of::<A>(), TypeId::of::<B>(), TypeId::of::<C>()];
+        self.set_fn(
+            name,
+            Public,
+            &args,
+            CallableFunction::from_method(Box::new(f)),
+        )
+    }
+
+    /// Set a Rust function taking four parameters into the module, returning a hash key.
+    ///
+    /// If there is a similar existing Rust function, it is replaced.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rhai::{Module, ImmutableString};
+    ///
+    /// let mut module = Module::new();
+    /// let hash = module.set_fn_4("calc", |x: i64, y: ImmutableString, z: i64, _w: ()| {
+    ///     Ok(x + y.len() as i64 + z)
+    /// });
+    /// assert!(module.get_fn(hash).is_some());
+    /// ```
+    pub fn set_fn_4<
+        A: Variant + Clone,
+        B: Variant + Clone,
+        C: Variant + Clone,
+        D: Variant + Clone,
+        T: Variant + Clone,
+    >(
+        &mut self,
+        name: impl Into<String>,
+        #[cfg(not(feature = "sync"))] func: impl Fn(A, B, C, D) -> FuncReturn<T> + 'static,
+        #[cfg(feature = "sync")] func: impl Fn(A, B, C, D) -> FuncReturn<T> + Send + Sync + 'static,
+    ) -> u64 {
+        let f = move |args: &mut FnCallArgs| {
+            let a = mem::take(args[0]).cast::<A>();
+            let b = mem::take(args[1]).cast::<B>();
+            let c = mem::take(args[2]).cast::<C>();
+            let d = mem::take(args[3]).cast::<D>();
+
+            func(a, b, c, d).map(Dynamic::from)
+        };
+        let args = [
+            TypeId::of::<A>(),
+            TypeId::of::<B>(),
+            TypeId::of::<C>(),
+            TypeId::of::<D>(),
+        ];
+        self.set_fn(
+            name,
+            Public,
+            &args,
+            CallableFunction::from_pure(Box::new(f)),
+        )
+    }
+
+    /// Set a Rust function taking four parameters (the first one mutable) into the module,
+    /// returning a hash key.
+    ///
+    /// If there is a similar existing Rust function, it is replaced.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rhai::{Module, ImmutableString};
+    ///
+    /// let mut module = Module::new();
+    /// let hash = module.set_fn_4_mut("calc", |x: &mut i64, y: ImmutableString, z: i64, _w: ()| {
+    ///     *x += y.len() as i64 + z; Ok(*x)
+    /// });
+    /// assert!(module.get_fn(hash).is_some());
+    /// ```
+    pub fn set_fn_4_mut<
+        A: Variant + Clone,
+        B: Variant + Clone,
+        C: Variant + Clone,
+        D: Variant + Clone,
+        T: Variant + Clone,
+    >(
+        &mut self,
+        name: impl Into<String>,
+        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A, B, C, D) -> FuncReturn<T> + 'static,
+        #[cfg(feature = "sync")] func: impl Fn(&mut A, B, C, D) -> FuncReturn<T> + Send + Sync + 'static,
+    ) -> u64 {
+        let f = move |args: &mut FnCallArgs| {
+            let b = mem::take(args[1]).cast::<B>();
+            let c = mem::take(args[2]).cast::<C>();
+            let d = mem::take(args[3]).cast::<D>();
+            let a = args[0].downcast_mut::<A>().unwrap();
+
+            func(a, b, c, d).map(Dynamic::from)
+        };
+        let args = [
+            TypeId::of::<A>(),
+            TypeId::of::<B>(),
+            TypeId::of::<C>(),
+            TypeId::of::<C>(),
+        ];
+        self.set_fn(
+            name,
+            Public,
+            &args,
+            CallableFunction::from_method(Box::new(f)),
+        )
     }
 
     /// Get a Rust function.
@@ -531,35 +729,25 @@ impl Module {
     /// let hash = module.set_fn_1("calc", |x: i64| Ok(x + 1));
     /// assert!(module.get_fn(hash).is_some());
     /// ```
-    pub fn get_fn(&self, hash_fn: u64) -> Option<&Box<dyn NativeCallable>> {
-        self.functions.get(&hash_fn).map(|(_, _, _, v)| v.as_ref())
+    pub fn get_fn(&self, hash_fn: u64) -> Option<&CallableFunction> {
+        self.functions.get(&hash_fn).map(|(_, _, _, v)| v)
     }
 
     /// Get a modules-qualified function.
     ///
-    /// The `u64` hash is calculated by the function `crate::calc_fn_hash`.
-    /// It is also returned by the `set_fn_XXX` calls.
+    /// The `u64` hash is calculated by the function `crate::calc_fn_hash` and must match
+    /// the hash calculated by `index_all_sub_modules`.
     pub(crate) fn get_qualified_fn(
         &mut self,
         name: &str,
         hash_fn_native: u64,
-    ) -> Result<&Box<dyn NativeCallable>, Box<EvalAltResult>> {
-        self.all_functions
-            .get(&hash_fn_native)
-            .map(|f| f.as_ref())
-            .ok_or_else(|| {
-                Box::new(EvalAltResult::ErrorFunctionNotFound(
-                    name.to_string(),
-                    Position::none(),
-                ))
-            })
-    }
-
-    /// Get a modules-qualified script-defined functions.
-    ///
-    /// The `u64` hash is calculated by the function `crate::calc_fn_hash`.
-    pub(crate) fn get_qualified_scripted_fn(&mut self, hash_fn_def: u64) -> Option<&FnDef> {
-        self.all_fn_lib.get_function(hash_fn_def)
+    ) -> Result<&CallableFunction, Box<EvalAltResult>> {
+        self.all_functions.get(&hash_fn_native).ok_or_else(|| {
+            Box::new(EvalAltResult::ErrorFunctionNotFound(
+                name.to_string(),
+                Position::none(),
+            ))
+        })
     }
 
     /// Create a new `Module` by evaluating an `AST`.
@@ -607,7 +795,7 @@ impl Module {
             },
         );
 
-        module.fn_lib = module.fn_lib.merge(ast.fn_lib());
+        module.lib = module.lib.merge(ast.lib());
 
         Ok(module)
     }
@@ -620,77 +808,66 @@ impl Module {
             module: &'a Module,
             qualifiers: &mut Vec<&'a str>,
             variables: &mut Vec<(u64, Dynamic)>,
-            functions: &mut Vec<(u64, SharedNativeFunction)>,
-            fn_lib: &mut Vec<(u64, SharedFnDef)>,
+            functions: &mut Vec<(u64, CallableFunction)>,
         ) {
             for (name, m) in &module.modules {
                 // Index all the sub-modules first.
                 qualifiers.push(name);
-                index_module(m, qualifiers, variables, functions, fn_lib);
+                index_module(m, qualifiers, variables, functions);
                 qualifiers.pop();
             }
 
             // Index all variables
             for (var_name, value) in &module.variables {
                 // Qualifiers + variable name
-                let hash_var = calc_fn_hash(qualifiers.iter().map(|&v| v), var_name, empty());
+                let hash_var = calc_fn_hash(qualifiers.iter().map(|&v| v), var_name, 0, empty());
                 variables.push((hash_var, value.clone()));
             }
             // Index all Rust functions
             for (name, access, params, func) in module.functions.values() {
                 match access {
                     // Private functions are not exported
-                    FnAccess::Private => continue,
-                    FnAccess::Public => (),
+                    Private => continue,
+                    Public => (),
                 }
                 // Rust functions are indexed in two steps:
                 // 1) Calculate a hash in a similar manner to script-defined functions,
-                //    i.e. qualifiers + function name + dummy parameter types (one for each parameter).
-                let hash_fn_def = calc_fn_hash(
-                    qualifiers.iter().map(|&v| v),
-                    name,
-                    repeat(EMPTY_TYPE_ID()).take(params.len()),
-                );
-                // 2) Calculate a second hash with no qualifiers, empty function name, and
-                //    the actual list of parameter `TypeId`'.s
-                let hash_fn_args = calc_fn_hash(empty(), "", params.iter().cloned());
+                //    i.e. qualifiers + function name + number of arguments.
+                let hash_fn_def =
+                    calc_fn_hash(qualifiers.iter().map(|&v| v), name, params.len(), empty());
+                // 2) Calculate a second hash with no qualifiers, empty function name,
+                //    zero number of arguments, and the actual list of argument `TypeId`'.s
+                let hash_fn_args = calc_fn_hash(empty(), "", 0, params.iter().cloned());
                 // 3) The final hash is the XOR of the two hashes.
                 let hash_fn_native = hash_fn_def ^ hash_fn_args;
 
                 functions.push((hash_fn_native, func.clone()));
             }
             // Index all script-defined functions
-            for fn_def in module.fn_lib.values() {
+            for fn_def in module.lib.values() {
                 match fn_def.access {
                     // Private functions are not exported
-                    FnAccess::Private => continue,
-                    DEF_ACCESS => (),
+                    Private => continue,
+                    Public => (),
                 }
-                // Qualifiers + function name + placeholders (one for each parameter)
+                // Qualifiers + function name + number of arguments.
                 let hash_fn_def = calc_fn_hash(
                     qualifiers.iter().map(|&v| v),
                     &fn_def.name,
-                    repeat(EMPTY_TYPE_ID()).take(fn_def.params.len()),
+                    fn_def.params.len(),
+                    empty(),
                 );
-                fn_lib.push((hash_fn_def, fn_def.clone()));
+                functions.push((hash_fn_def, CallableFunction::Script(fn_def.clone()).into()));
             }
         }
 
         let mut variables = Vec::new();
         let mut functions = Vec::new();
-        let mut fn_lib = Vec::new();
 
-        index_module(
-            self,
-            &mut vec!["root"],
-            &mut variables,
-            &mut functions,
-            &mut fn_lib,
-        );
+        index_module(self, &mut vec!["root"], &mut variables, &mut functions);
 
         self.all_variables = variables.into_iter().collect();
         self.all_functions = functions.into_iter().collect();
-        self.all_fn_lib = fn_lib.into();
     }
 
     /// Does a type iterator exist in the module?
@@ -699,16 +876,13 @@ impl Module {
     }
 
     /// Set a type iterator into the module.
-    pub fn set_iter(&mut self, typ: TypeId, func: Box<IteratorFn>) {
-        #[cfg(not(feature = "sync"))]
-        self.type_iterators.insert(typ, Rc::new(func));
-        #[cfg(feature = "sync")]
-        self.type_iterators.insert(typ, Arc::new(func));
+    pub fn set_iter(&mut self, typ: TypeId, func: IteratorFn) {
+        self.type_iterators.insert(typ, func);
     }
 
     /// Get the specified type iterator.
-    pub fn get_iter(&self, id: TypeId) -> Option<&SharedIteratorFunction> {
-        self.type_iterators.get(&id)
+    pub fn get_iter(&self, id: TypeId) -> Option<IteratorFn> {
+        self.type_iterators.get(&id).cloned()
     }
 }
 
@@ -952,6 +1126,9 @@ mod stat {
 
     /// Module resolution service that serves modules added into it.
     ///
+    /// `StaticModuleResolver` is a smart pointer to a `HashMap<String, Module>`.
+    /// It can simply be treated as `&HashMap<String, Module>`.
+    ///
     /// # Examples
     ///
     /// ```

src/optimize.rs

@@ -1,11 +1,9 @@
 use crate::any::Dynamic;
 use crate::calc_fn_hash;
 use crate::engine::{
-    Engine, FunctionsLib, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_PRINT, KEYWORD_TYPE_OF,
+    Engine, FunctionsLib,  KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_PRINT,
+    KEYWORD_TYPE_OF,
 };
-use crate::fn_native::FnCallArgs;
-use crate::module::Module;
-use crate::packages::PackagesCollection;
 use crate::parser::{map_dynamic_to_expr, Expr, FnDef, ReturnType, Stmt, AST};
 use crate::result::EvalAltResult;
 use crate::scope::{Entry as ScopeEntry, EntryType as ScopeEntryType, Scope};
@@ -15,7 +13,6 @@ use crate::utils::StaticVec;
 use crate::stdlib::{
     boxed::Box,
     iter::empty,
-    mem,
     string::{String, ToString},
     vec,
     vec::Vec,
@@ -40,6 +37,10 @@ impl OptimizationLevel {
     pub fn is_none(self) -> bool {
         self == Self::None
     }
+    /// Is the `OptimizationLevel` Simple.
+    pub fn is_simple(self) -> bool {
+        self == Self::Simple
+    }
     /// Is the `OptimizationLevel` Full.
     pub fn is_full(self) -> bool {
         self == Self::Full
@@ -55,23 +56,19 @@ struct State<'a> {
     /// An `Engine` instance for eager function evaluation.
     engine: &'a Engine,
     /// Library of script-defined functions.
-    fn_lib: &'a [(&'a str, usize)],
+    lib: &'a FunctionsLib,
     /// Optimization level.
     optimization_level: OptimizationLevel,
 }
 
 impl<'a> State<'a> {
     /// Create a new State.
-    pub fn new(
-        engine: &'a Engine,
-        fn_lib: &'a [(&'a str, usize)],
-        level: OptimizationLevel,
-    ) -> Self {
+    pub fn new(engine: &'a Engine, lib: &'a FunctionsLib, level: OptimizationLevel) -> Self {
         Self {
             changed: false,
             constants: vec![],
             engine,
-            fn_lib,
+            lib,
             optimization_level: level,
         }
     }
@@ -112,26 +109,40 @@ impl<'a> State<'a> {
 }
 
 /// Call a registered function
-fn call_fn(
-    packages: &PackagesCollection,
-    global_module: &Module,
+fn call_fn_with_constant_arguments(
+    state: &State,
     fn_name: &str,
-    args: &mut FnCallArgs,
+    arg_values: &mut [Dynamic],
     pos: Position,
 ) -> Result<Option<Dynamic>, Box<EvalAltResult>> {
     // Search built-in's and external functions
-    let hash = calc_fn_hash(empty(), fn_name, args.iter().map(|a| a.type_id()));
+    let hash_fn = calc_fn_hash(
+        empty(),
+        fn_name,
+        arg_values.len(),
+        arg_values.iter().map(|a| a.type_id()),
+    );
 
-    global_module
-        .get_fn(hash)
-        .or_else(|| packages.get_fn(hash))
-        .map(|func| func.call(args))
-        .transpose()
-        .map_err(|err| err.new_position(pos))
+    state
+        .engine
+        .call_fn_raw(
+            &mut Scope::new(),
+            &mut Default::default(),
+            state.lib,
+            fn_name,
+            (hash_fn, 0),
+            arg_values.iter_mut().collect::<StaticVec<_>>().as_mut(),
+            false,
+            None,
+            pos,
+            0,
+        )
+        .map(|(v, _)| Some(v))
+        .or_else(|_| Ok(None))
 }
 
 /// Optimize a statement.
-fn optimize_stmt<'a>(stmt: Stmt, state: &mut State<'a>, preserve_result: bool) -> Stmt {
+fn optimize_stmt(stmt: Stmt, state: &mut State, preserve_result: bool) -> Stmt {
     match stmt {
         // if expr { Noop }
         Stmt::IfThenElse(x) if matches!(x.1, Stmt::Noop(_)) => {
@@ -352,11 +363,13 @@ fn optimize_stmt<'a>(stmt: Stmt, state: &mut State<'a>, preserve_result: bool) -
 }
 
 /// Optimize an expression.
-fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
+fn optimize_expr(expr: Expr, state: &mut State) -> Expr {
     // These keywords are handled specially
     const DONT_EVAL_KEYWORDS: [&str; 3] = [KEYWORD_PRINT, KEYWORD_DEBUG, KEYWORD_EVAL];
 
     match expr {
+        // expr - do not promote because there is a reason it is wrapped in an `Expr::Expr`
+        Expr::Expr(x) => Expr::Expr(Box::new(optimize_expr(*x, state))),
         // ( stmt )
         Expr::Stmt(x) => match optimize_stmt(x.0, state, true) {
             // ( Noop ) -> ()
@@ -372,27 +385,23 @@ fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
             // ( stmt )
             stmt => Expr::Stmt(Box::new((stmt, x.1))),
         },
-        // id = expr
-        Expr::Assignment(x) => match x.1 {
-            //id = id2 = expr2
-            Expr::Assignment(x2) => match (x.0, x2.0) {
-                // var = var = expr2 -> var = expr2
+        // id op= expr
+        Expr::Assignment(x) => match x.2 {
+            //id = id2 op= rhs
+            Expr::Assignment(x2) if x.1.is_empty() => match (x.0, &x2.0) {
+                // var = var op= expr2 -> var op= expr2
                 (Expr::Variable(a), Expr::Variable(b))
                     if a.1.is_none() && b.1.is_none() && a.0 == b.0 && a.3 == b.3 =>
                 {
                     // Assignment to the same variable - fold
                     state.set_dirty();
-                    Expr::Assignment(Box::new((Expr::Variable(a), optimize_expr(x2.1, state), x.2)))
-                }
-                // id1 = id2 = expr2
-                (id1, id2) => {
-                    Expr::Assignment(Box::new((
-                        id1, Expr::Assignment(Box::new((id2, optimize_expr(x2.1, state), x2.2))), x.2,
-                    )))
+                    Expr::Assignment(Box::new((Expr::Variable(a), x2.1, optimize_expr(x2.2, state), x.3)))
                 }
+                // expr1 = expr2 op= rhs
+                (expr1, _) => Expr::Assignment(Box::new((expr1, x.1, optimize_expr(Expr::Assignment(x2), state), x.3))),
             },
-            // id = expr
-            expr => Expr::Assignment(Box::new((x.0, optimize_expr(expr, state), x.2))),
+            // expr = rhs
+            expr => Expr::Assignment(Box::new((x.0, x.1, optimize_expr(expr, state), x.3))),
         },
 
         // lhs.rhs
@@ -431,7 +440,7 @@ fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
                 // All other items can be thrown away.
                 state.set_dirty();
                 let pos = m.1;
-                m.0.into_iter().find(|((name, _), _)| name == &s.0)
+                m.0.into_iter().find(|((name, _), _)| name == s.0.as_ref())
                     .map(|(_, expr)| expr.set_position(pos))
                     .unwrap_or_else(|| Expr::Unit(pos))
             }
@@ -459,7 +468,7 @@ fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
             // "xxx" in "xxxxx"
             (Expr::StringConstant(a), Expr::StringConstant(b)) => {
                 state.set_dirty();
-                if b.0.contains(&a.0) { Expr::True(a.1) } else { Expr::False(a.1) }
+                if b.0.contains(a.0.as_ref()) { Expr::True(a.1) } else { Expr::False(a.1) }
             }
             // 'x' in "xxxxx"
             (Expr::CharConstant(a), Expr::StringConstant(b)) => {
@@ -469,7 +478,7 @@ fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
             // "xxx" in #{...}
             (Expr::StringConstant(a), Expr::Map(b)) => {
                 state.set_dirty();
-                if b.0.iter().find(|((name, _), _)| name == &a.0).is_some() {
+                if b.0.iter().find(|((name, _), _)| name == a.0.as_ref()).is_some() {
                     Expr::True(a.1)
                 } else {
                     Expr::False(a.1)
@@ -542,27 +551,30 @@ fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
                 && state.optimization_level == OptimizationLevel::Full // full optimizations
                 && x.3.iter().all(|expr| expr.is_constant()) // all arguments are constants
         => {
-            let ((name, pos), _, _, args, def_value) = x.as_mut();
+            let ((name, native_only, pos), _, _, args, def_value) = x.as_mut();
 
             // First search in script-defined functions (can override built-in)
-            if state.fn_lib.iter().find(|(id, len)| *id == name && *len == args.len()).is_some() {
+            // Cater for both normal function call style and method call style (one additional arguments)
+            if !*native_only && state.lib.values().find(|f| 
+                &f.name == name
+                && (args.len()..=args.len() + 1).contains(&f.params.len())
+            ).is_some() {
                 // A script-defined function overrides the built-in function - do not make the call
                 x.3 = x.3.into_iter().map(|a| optimize_expr(a, state)).collect();
                 return Expr::FnCall(x);
             }
 
             let mut arg_values: StaticVec<_> = args.iter().map(Expr::get_constant_value).collect();
-            let mut call_args: StaticVec<_> = arg_values.iter_mut().collect();
 
             // Save the typename of the first argument if it is `type_of()`
             // This is to avoid `call_args` being passed into the closure
-            let arg_for_type_of = if name == KEYWORD_TYPE_OF && call_args.len() == 1 {
-                state.engine.map_type_name(call_args[0].type_name())
+            let arg_for_type_of = if name == KEYWORD_TYPE_OF && arg_values.len() == 1 {
+                state.engine.map_type_name(arg_values[0].type_name())
             } else {
                 ""
             };
 
-            call_fn(&state.engine.packages, &state.engine.global_module, name, call_args.as_mut(), *pos).ok()
+            call_fn_with_constant_arguments(&state, name, arg_values.as_mut(), *pos).ok()
                 .and_then(|result|
                     result.or_else(|| {
                         if !arg_for_type_of.is_empty() {
@@ -604,11 +616,11 @@ fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
     }
 }
 
-fn optimize<'a>(
+fn optimize(
     statements: Vec<Stmt>,
     engine: &Engine,
     scope: &Scope,
-    fn_lib: &'a [(&'a str, usize)],
+    lib: &FunctionsLib,
     level: OptimizationLevel,
 ) -> Vec<Stmt> {
     // If optimization level is None then skip optimizing
@@ -617,7 +629,7 @@ fn optimize<'a>(
     }
 
     // Set up the state
-    let mut state = State::new(engine, fn_lib, level);
+    let mut state = State::new(engine, lib, level);
 
     // Add constants from the scope into the state
     scope
@@ -702,41 +714,35 @@ pub fn optimize_into_ast(
     const level: OptimizationLevel = OptimizationLevel::None;
 
     #[cfg(not(feature = "no_function"))]
-    let fn_lib_values: StaticVec<_> = functions
-        .iter()
-        .map(|fn_def| (fn_def.name.as_str(), fn_def.params.len()))
-        .collect();
-
-    #[cfg(not(feature = "no_function"))]
-    let fn_lib = fn_lib_values.as_ref();
-
-    #[cfg(feature = "no_function")]
-    const fn_lib: &[(&str, usize)] = &[];
-
-    #[cfg(not(feature = "no_function"))]
-    let lib = FunctionsLib::from_iter(functions.iter().cloned().map(|mut fn_def| {
+    let lib = {
         if !level.is_none() {
-            let pos = fn_def.body.position();
+            let lib = FunctionsLib::from_iter(functions.iter().cloned());
 
-            // Optimize the function body
-            let mut body = optimize(vec![fn_def.body], engine, &Scope::new(), fn_lib, level);
+            FunctionsLib::from_iter(functions.into_iter().map(|mut fn_def| {
+                let pos = fn_def.body.position();
 
-            // {} -> Noop
-            fn_def.body = match body.pop().unwrap_or_else(|| Stmt::Noop(pos)) {
-                // { return val; } -> val
-                Stmt::ReturnWithVal(x) if x.1.is_some() && (x.0).0 == ReturnType::Return => {
-                    Stmt::Expr(Box::new(x.1.unwrap()))
-                }
-                // { return; } -> ()
-                Stmt::ReturnWithVal(x) if x.1.is_none() && (x.0).0 == ReturnType::Return => {
-                    Stmt::Expr(Box::new(Expr::Unit((x.0).1)))
-                }
-                // All others
-                stmt => stmt,
-            };
+                // Optimize the function body
+                let mut body = optimize(vec![fn_def.body], engine, &Scope::new(), &lib, level);
+
+                // {} -> Noop
+                fn_def.body = match body.pop().unwrap_or_else(|| Stmt::Noop(pos)) {
+                    // { return val; } -> val
+                    Stmt::ReturnWithVal(x) if x.1.is_some() && (x.0).0 == ReturnType::Return => {
+                        Stmt::Expr(Box::new(x.1.unwrap()))
+                    }
+                    // { return; } -> ()
+                    Stmt::ReturnWithVal(x) if x.1.is_none() && (x.0).0 == ReturnType::Return => {
+                        Stmt::Expr(Box::new(Expr::Unit((x.0).1)))
+                    }
+                    // All others
+                    stmt => stmt,
+                };
+                fn_def
+            }))
+        } else {
+            FunctionsLib::from_iter(functions.into_iter())
         }
-        fn_def
-    }));
+    };
 
     #[cfg(feature = "no_function")]
     let lib: FunctionsLib = Default::default();
@@ -745,7 +751,7 @@ pub fn optimize_into_ast(
         match level {
             OptimizationLevel::None => statements,
             OptimizationLevel::Simple | OptimizationLevel::Full => {
-                optimize(statements, engine, &scope, fn_lib, level)
+                optimize(statements, engine, &scope, &lib, level)
             }
         },
         lib,

src/packages/arithmetic.rs

@@ -20,7 +20,7 @@ use crate::stdlib::{
 };
 
 // Checked add
-fn add<T: Display + CheckedAdd>(x: T, y: T) -> FuncReturn<T> {
+pub(crate) fn add<T: Display + CheckedAdd>(x: T, y: T) -> FuncReturn<T> {
     x.checked_add(&y).ok_or_else(|| {
         Box::new(EvalAltResult::ErrorArithmetic(
             format!("Addition overflow: {} + {}", x, y),
@@ -29,7 +29,7 @@ fn add<T: Display + CheckedAdd>(x: T, y: T) -> FuncReturn<T> {
     })
 }
 // Checked subtract
-fn sub<T: Display + CheckedSub>(x: T, y: T) -> FuncReturn<T> {
+pub(crate) fn sub<T: Display + CheckedSub>(x: T, y: T) -> FuncReturn<T> {
     x.checked_sub(&y).ok_or_else(|| {
         Box::new(EvalAltResult::ErrorArithmetic(
             format!("Subtraction underflow: {} - {}", x, y),
@@ -38,7 +38,7 @@ fn sub<T: Display + CheckedSub>(x: T, y: T) -> FuncReturn<T> {
     })
 }
 // Checked multiply
-fn mul<T: Display + CheckedMul>(x: T, y: T) -> FuncReturn<T> {
+pub(crate) fn mul<T: Display + CheckedMul>(x: T, y: T) -> FuncReturn<T> {
     x.checked_mul(&y).ok_or_else(|| {
         Box::new(EvalAltResult::ErrorArithmetic(
             format!("Multiplication overflow: {} * {}", x, y),
@@ -47,7 +47,7 @@ fn mul<T: Display + CheckedMul>(x: T, y: T) -> FuncReturn<T> {
     })
 }
 // Checked divide
-fn div<T>(x: T, y: T) -> FuncReturn<T>
+pub(crate) fn div<T>(x: T, y: T) -> FuncReturn<T>
 where
     T: Display + CheckedDiv + PartialEq + Zero,
 {
@@ -67,7 +67,7 @@ where
     })
 }
 // Checked negative - e.g. -(i32::MIN) will overflow i32::MAX
-fn neg<T: Display + CheckedNeg>(x: T) -> FuncReturn<T> {
+pub(crate) fn neg<T: Display + CheckedNeg>(x: T) -> FuncReturn<T> {
     x.checked_neg().ok_or_else(|| {
         Box::new(EvalAltResult::ErrorArithmetic(
             format!("Negation overflow: -{}", x),
@@ -76,7 +76,7 @@ fn neg<T: Display + CheckedNeg>(x: T) -> FuncReturn<T> {
     })
 }
 // Checked absolute
-fn abs<T: Display + CheckedNeg + PartialOrd + Zero>(x: T) -> FuncReturn<T> {
+pub(crate) fn abs<T: Display + CheckedNeg + PartialOrd + Zero>(x: T) -> FuncReturn<T> {
     // FIX - We don't use Signed::abs() here because, contrary to documentation, it panics
     //       when the number is ::MIN instead of returning ::MIN itself.
     if x >= <T as Zero>::zero() {
@@ -133,7 +133,7 @@ fn binary_xor<T: BitXor>(x: T, y: T) -> FuncReturn<<T as BitXor>::Output> {
     Ok(x ^ y)
 }
 // Checked left-shift
-fn shl<T: Display + CheckedShl>(x: T, y: INT) -> FuncReturn<T> {
+pub(crate) fn shl<T: Display + CheckedShl>(x: T, y: INT) -> FuncReturn<T> {
     // Cannot shift by a negative number of bits
     if y < 0 {
         return Err(Box::new(EvalAltResult::ErrorArithmetic(
@@ -150,7 +150,7 @@ fn shl<T: Display + CheckedShl>(x: T, y: INT) -> FuncReturn<T> {
     })
 }
 // Checked right-shift
-fn shr<T: Display + CheckedShr>(x: T, y: INT) -> FuncReturn<T> {
+pub(crate) fn shr<T: Display + CheckedShr>(x: T, y: INT) -> FuncReturn<T> {
     // Cannot shift by a negative number of bits
     if y < 0 {
         return Err(Box::new(EvalAltResult::ErrorArithmetic(
@@ -167,15 +167,15 @@ fn shr<T: Display + CheckedShr>(x: T, y: INT) -> FuncReturn<T> {
     })
 }
 // Unchecked left-shift - may panic if shifting by a negative number of bits
-fn shl_u<T: Shl<T>>(x: T, y: T) -> FuncReturn<<T as Shl<T>>::Output> {
+pub(crate) fn shl_u<T: Shl<T>>(x: T, y: T) -> FuncReturn<<T as Shl<T>>::Output> {
     Ok(x.shl(y))
 }
 // Unchecked right-shift - may panic if shifting by a negative number of bits
-fn shr_u<T: Shr<T>>(x: T, y: T) -> FuncReturn<<T as Shr<T>>::Output> {
+pub(crate) fn shr_u<T: Shr<T>>(x: T, y: T) -> FuncReturn<<T as Shr<T>>::Output> {
     Ok(x.shr(y))
 }
 // Checked modulo
-fn modulo<T: Display + CheckedRem>(x: T, y: T) -> FuncReturn<T> {
+pub(crate) fn modulo<T: Display + CheckedRem>(x: T, y: T) -> FuncReturn<T> {
     x.checked_rem(&y).ok_or_else(|| {
         Box::new(EvalAltResult::ErrorArithmetic(
             format!("Modulo division by zero or overflow: {} % {}", x, y),
@@ -188,7 +188,7 @@ fn modulo_u<T: Rem>(x: T, y: T) -> FuncReturn<<T as Rem>::Output> {
     Ok(x % y)
 }
 // Checked power
-fn pow_i_i(x: INT, y: INT) -> FuncReturn<INT> {
+pub(crate) fn pow_i_i(x: INT, y: INT) -> FuncReturn<INT> {
     #[cfg(not(feature = "only_i32"))]
     {
         if y > (u32::MAX as INT) {
@@ -229,17 +229,17 @@ fn pow_i_i(x: INT, y: INT) -> FuncReturn<INT> {
     }
 }
 // Unchecked integer power - may panic on overflow or if the power index is too high (> u32::MAX)
-fn pow_i_i_u(x: INT, y: INT) -> FuncReturn<INT> {
+pub(crate) fn pow_i_i_u(x: INT, y: INT) -> FuncReturn<INT> {
     Ok(x.pow(y as u32))
 }
 // Floating-point power - always well-defined
 #[cfg(not(feature = "no_float"))]
-fn pow_f_f(x: FLOAT, y: FLOAT) -> FuncReturn<FLOAT> {
+pub(crate) fn pow_f_f(x: FLOAT, y: FLOAT) -> FuncReturn<FLOAT> {
     Ok(x.powf(y))
 }
 // Checked power
 #[cfg(not(feature = "no_float"))]
-fn pow_f_i(x: FLOAT, y: INT) -> FuncReturn<FLOAT> {
+pub(crate) fn pow_f_i(x: FLOAT, y: INT) -> FuncReturn<FLOAT> {
     // Raise to power that is larger than an i32
     if y > (i32::MAX as INT) {
         return Err(Box::new(EvalAltResult::ErrorArithmetic(
@@ -253,7 +253,7 @@ fn pow_f_i(x: FLOAT, y: INT) -> FuncReturn<FLOAT> {
 // Unchecked power - may be incorrect if the power index is too high (> i32::MAX)
 #[cfg(feature = "unchecked")]
 #[cfg(not(feature = "no_float"))]
-fn pow_f_i_u(x: FLOAT, y: INT) -> FuncReturn<FLOAT> {
+pub(crate) fn pow_f_i_u(x: FLOAT, y: INT) -> FuncReturn<FLOAT> {
     Ok(x.powi(y as i32))
 }
 
@@ -269,119 +269,69 @@ macro_rules! reg_op {
 }
 
 def_package!(crate:ArithmeticPackage:"Basic arithmetic", lib, {
-    // Checked basic arithmetic
-    #[cfg(not(feature = "unchecked"))]
+    #[cfg(not(feature = "only_i32"))]
+    #[cfg(not(feature = "only_i64"))]
     {
-        reg_op!(lib, "+", add, INT);
-        reg_op!(lib, "-", sub, INT);
-        reg_op!(lib, "*", mul, INT);
-        reg_op!(lib, "/", div, INT);
-
-        #[cfg(not(feature = "only_i32"))]
-        #[cfg(not(feature = "only_i64"))]
+        #[cfg(not(feature = "unchecked"))]
         {
-            reg_op!(lib, "+", add, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, "-", sub, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, "*", mul, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, "/", div, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
+            // Checked basic arithmetic
+            reg_op!(lib, "+", add, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, "-", sub, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, "*", mul, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, "/", div, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            // Checked bit shifts
+            reg_op!(lib, "<<", shl, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, ">>", shr, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, "%", modulo, i8, u8, i16, u16, i32, u32, u64, i128, u128);
         }
-    }
 
-    // Unchecked basic arithmetic
-    #[cfg(feature = "unchecked")]
-    {
-        reg_op!(lib, "+", add_u, INT);
-        reg_op!(lib, "-", sub_u, INT);
-        reg_op!(lib, "*", mul_u, INT);
-        reg_op!(lib, "/", div_u, INT);
-
-        #[cfg(not(feature = "only_i32"))]
-        #[cfg(not(feature = "only_i64"))]
+        #[cfg(feature = "unchecked")]
         {
-            reg_op!(lib, "+", add_u, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, "-", sub_u, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, "*", mul_u, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, "/", div_u, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
+            // Unchecked basic arithmetic
+            reg_op!(lib, "+", add_u, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, "-", sub_u, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, "*", mul_u, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, "/", div_u, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            // Unchecked bit shifts
+            reg_op!(lib, "<<", shl_u, i64, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, ">>", shr_u, i64, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+            reg_op!(lib, "%", modulo_u, i8, u8, i16, u16, i32, u32, u64, i128, u128);
         }
     }
 
     // Basic arithmetic for floating-point - no need to check
     #[cfg(not(feature = "no_float"))]
     {
-        reg_op!(lib, "+", add_u, f32, f64);
-        reg_op!(lib, "-", sub_u, f32, f64);
-        reg_op!(lib, "*", mul_u, f32, f64);
-        reg_op!(lib, "/", div_u, f32, f64);
+        reg_op!(lib, "+", add_u, f32);
+        reg_op!(lib, "-", sub_u, f32);
+        reg_op!(lib, "*", mul_u, f32);
+        reg_op!(lib, "/", div_u, f32);
     }
 
-    // Bit operations
-    reg_op!(lib, "|", binary_or, INT);
-    reg_op!(lib, "&", binary_and, INT);
-    reg_op!(lib, "^", binary_xor, INT);
-
     #[cfg(not(feature = "only_i32"))]
     #[cfg(not(feature = "only_i64"))]
     {
-        reg_op!(lib, "|", binary_or, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-        reg_op!(lib, "&", binary_and, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-        reg_op!(lib, "^", binary_xor, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
+        reg_op!(lib, "|", binary_or, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+        reg_op!(lib, "&", binary_and, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+        reg_op!(lib, "^", binary_xor, i8, u8, i16, u16, i32, u32, u64, i128, u128);
     }
 
-    // Checked bit shifts
-    #[cfg(not(feature = "unchecked"))]
-    {
-        reg_op!(lib, "<<", shl, INT);
-        reg_op!(lib, ">>", shr, INT);
-        reg_op!(lib, "%", modulo, INT);
-
-        #[cfg(not(feature = "only_i32"))]
-        #[cfg(not(feature = "only_i64"))]
-        {
-            reg_op!(lib, "<<", shl, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, ">>", shr, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, "%", modulo, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-        }
-    }
-
-    // Unchecked bit shifts
-    #[cfg(feature = "unchecked")]
-    {
-        reg_op!(lib, "<<", shl_u, INT, INT);
-        reg_op!(lib, ">>", shr_u, INT, INT);
-        reg_op!(lib, "%", modulo_u, INT);
-
-        #[cfg(not(feature = "only_i32"))]
-        #[cfg(not(feature = "only_i64"))]
-        {
-            reg_op!(lib, "<<", shl_u, i64, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, ">>", shr_u, i64, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-            reg_op!(lib, "%", modulo_u, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-        }
-    }
-
-    // Checked power
-    #[cfg(not(feature = "unchecked"))]
-    {
-        lib.set_fn_2("~", pow_i_i);
-
-        #[cfg(not(feature = "no_float"))]
-        lib.set_fn_2("~", pow_f_i);
-    }
-
-    // Unchecked power
-    #[cfg(feature = "unchecked")]
-    {
-        lib.set_fn_2("~", pow_i_i_u);
-
-        #[cfg(not(feature = "no_float"))]
-        lib.set_fn_2("~", pow_f_i_u);
-    }
-
-    // Floating-point modulo and power
     #[cfg(not(feature = "no_float"))]
     {
-        reg_op!(lib, "%", modulo_u, f32, f64);
-        lib.set_fn_2("~", pow_f_f);
+        // Checked power
+        #[cfg(not(feature = "unchecked"))]
+        lib.set_fn_2("~", pow_f_i);
+
+        // Unchecked power
+        #[cfg(feature = "unchecked")]
+        lib.set_fn_2("~", pow_f_i_u);
+
+        // Floating-point modulo and power
+        reg_op!(lib, "%", modulo_u, f32);
+
+        // Floating-point unary
+        reg_unary!(lib, "-", neg_u, f32, f64);
+        reg_unary!(lib, "abs", abs_u, f32, f64);
     }
 
     // Checked unary
@@ -411,11 +361,4 @@ def_package!(crate:ArithmeticPackage:"Basic arithmetic", lib, {
             reg_unary!(lib, "abs", abs_u, i8, i16, i32, i64, i128);
         }
     }
-
-    // Floating-point unary
-    #[cfg(not(feature = "no_float"))]
-    {
-        reg_unary!(lib, "-", neg_u, f32, f64);
-        reg_unary!(lib, "abs", abs_u, f32, f64);
-    }
 });

src/packages/array_basic.rs

@@ -4,9 +4,9 @@ use crate::any::{Dynamic, Variant};
 use crate::def_package;
 use crate::engine::Array;
 use crate::module::FuncReturn;
-use crate::parser::INT;
+use crate::parser::{ImmutableString, INT};
 
-use crate::stdlib::{any::TypeId, boxed::Box, string::String};
+use crate::stdlib::{any::TypeId, boxed::Box};
 
 // Register array utility functions
 fn push<T: Variant + Clone>(list: &mut Array, item: T) -> FuncReturn<()> {
@@ -45,14 +45,18 @@ macro_rules! reg_tri {
 
 #[cfg(not(feature = "no_index"))]
 def_package!(crate:BasicArrayPackage:"Basic array utilities.", lib, {
-    reg_op!(lib, "push", push, INT, bool, char, String, Array, ());
-    reg_tri!(lib, "pad", pad, INT, bool, char, String, Array, ());
-    reg_tri!(lib, "insert", ins, INT, bool, char, String, Array, ());
+    reg_op!(lib, "push", push, INT, bool, char, ImmutableString, Array, ());
+    reg_tri!(lib, "pad", pad, INT, bool, char, ImmutableString, Array, ());
+    reg_tri!(lib, "insert", ins, INT, bool, char, ImmutableString, Array, ());
 
     lib.set_fn_2_mut("append", |x: &mut Array, y: Array| {
         x.extend(y);
         Ok(())
     });
+    lib.set_fn_2_mut("+=", |x: &mut Array, y: Array| {
+        x.extend(y);
+        Ok(())
+    });
     lib.set_fn_2(
         "+",
         |mut x: Array, y: Array| {
@@ -101,6 +105,10 @@ def_package!(crate:BasicArrayPackage:"Basic array utilities.", lib, {
         },
     );
     lib.set_fn_1_mut("len", |list: &mut Array| Ok(list.len() as INT));
+
+    #[cfg(not(feature = "no_object"))]
+    lib.set_getter_fn("len", |list: &mut Array| Ok(list.len() as INT));
+
     lib.set_fn_1_mut("clear", |list: &mut Array| {
         list.clear();
         Ok(())
@@ -120,8 +128,6 @@ def_package!(crate:BasicArrayPackage:"Basic array utilities.", lib, {
     // Register array iterator
     lib.set_iter(
         TypeId::of::<Array>(),
-        Box::new(|arr| Box::new(
-            arr.cast::<Array>().into_iter()) as Box<dyn Iterator<Item = Dynamic>>
-        ),
+        |arr| Box::new(arr.cast::<Array>().into_iter()) as Box<dyn Iterator<Item = Dynamic>>,
     );
 });

src/packages/eval.rs

@@ -0,0 +1,12 @@
+use crate::def_package;
+use crate::module::FuncReturn;
+use crate::parser::ImmutableString;
+
+def_package!(crate:EvalPackage:"Disable 'eval'.", lib, {
+    lib.set_fn_1(
+        "eval",
+        |_: ImmutableString| -> FuncReturn<()> {
+            Err("eval is evil!".into())
+        },
+    );
+});

src/packages/iter_basic.rs

@@ -14,13 +14,10 @@ fn reg_range<T: Variant + Clone>(lib: &mut Module)
 where
     Range<T>: Iterator<Item = T>,
 {
-    lib.set_iter(
-        TypeId::of::<Range<T>>(),
-        Box::new(|source| {
-            Box::new(source.cast::<Range<T>>().map(|x| x.into_dynamic()))
-                as Box<dyn Iterator<Item = Dynamic>>
-        }),
-    );
+    lib.set_iter(TypeId::of::<Range<T>>(), |source| {
+        Box::new(source.cast::<Range<T>>().map(|x| x.into_dynamic()))
+            as Box<dyn Iterator<Item = Dynamic>>
+    });
 }
 
 fn get_range<T: Variant + Clone>(from: T, to: T) -> FuncReturn<Range<T>> {
@@ -58,13 +55,10 @@ where
     T: Variant + Clone + PartialOrd,
     StepRange<T>: Iterator<Item = T>,
 {
-    lib.set_iter(
-        TypeId::of::<StepRange<T>>(),
-        Box::new(|source| {
-            Box::new(source.cast::<StepRange<T>>().map(|x| x.into_dynamic()))
-                as Box<dyn Iterator<Item = Dynamic>>
-        }),
-    );
+    lib.set_iter(TypeId::of::<StepRange<T>>(), |source| {
+        Box::new(source.cast::<StepRange<T>>().map(|x| x.into_dynamic()))
+            as Box<dyn Iterator<Item = Dynamic>>
+    });
 }
 
 fn get_step_range<T>(from: T, to: T, step: T) -> FuncReturn<StepRange<T>>

src/packages/logic.rs

@@ -1,8 +1,5 @@
 use crate::def_package;
 use crate::module::FuncReturn;
-use crate::parser::INT;
-
-use crate::stdlib::string::String;
 
 // Comparison operators
 pub fn lt<T: PartialOrd>(x: T, y: T) -> FuncReturn<bool> {
@@ -25,12 +22,6 @@ pub fn ne<T: PartialEq>(x: T, y: T) -> FuncReturn<bool> {
 }
 
 // Logic operators
-fn and(x: bool, y: bool) -> FuncReturn<bool> {
-    Ok(x && y)
-}
-fn or(x: bool, y: bool) -> FuncReturn<bool> {
-    Ok(x || y)
-}
 fn not(x: bool) -> FuncReturn<bool> {
     Ok(!x)
 }
@@ -42,48 +33,26 @@ macro_rules! reg_op {
 }
 
 def_package!(crate:LogicPackage:"Logical operators.", lib, {
-    reg_op!(lib, "<", lt, INT, char);
-    reg_op!(lib, "<=", lte, INT, char);
-    reg_op!(lib, ">", gt, INT, char);
-    reg_op!(lib, ">=", gte, INT, char);
-    reg_op!(lib, "==", eq, INT, char, bool, ());
-    reg_op!(lib, "!=", ne, INT, char, bool, ());
-
-    // Special versions for strings - at least avoid copying the first string
-    lib.set_fn_2_mut("<", |x: &mut String, y: String| Ok(*x < y));
-    lib.set_fn_2_mut("<=", |x: &mut String, y: String| Ok(*x <= y));
-    lib.set_fn_2_mut(">", |x: &mut String, y: String| Ok(*x > y));
-    lib.set_fn_2_mut(">=", |x: &mut String, y: String| Ok(*x >= y));
-    lib.set_fn_2_mut("==", |x: &mut String, y: String| Ok(*x == y));
-    lib.set_fn_2_mut("!=", |x: &mut String, y: String| Ok(*x != y));
-
     #[cfg(not(feature = "only_i32"))]
     #[cfg(not(feature = "only_i64"))]
     {
-        reg_op!(lib, "<", lt, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-        reg_op!(lib, "<=", lte, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-        reg_op!(lib, ">", gt, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-        reg_op!(lib, ">=", gte, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-        reg_op!(lib, "==", eq, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
-        reg_op!(lib, "!=", ne, i8, u8, i16, u16, i32, i64, u32, u64, i128, u128);
+        reg_op!(lib, "<", lt, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+        reg_op!(lib, "<=", lte, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+        reg_op!(lib, ">", gt, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+        reg_op!(lib, ">=", gte, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+        reg_op!(lib, "==", eq, i8, u8, i16, u16, i32, u32, u64, i128, u128);
+        reg_op!(lib, "!=", ne, i8, u8, i16, u16, i32, u32, u64, i128, u128);
     }
 
     #[cfg(not(feature = "no_float"))]
     {
-        reg_op!(lib, "<", lt, f32, f64);
-        reg_op!(lib, "<=", lte, f32, f64);
-        reg_op!(lib, ">", gt, f32, f64);
-        reg_op!(lib, ">=", gte, f32, f64);
-        reg_op!(lib, "==", eq, f32, f64);
-        reg_op!(lib, "!=", ne, f32, f64);
+        reg_op!(lib, "<", lt, f32);
+        reg_op!(lib, "<=", lte, f32);
+        reg_op!(lib, ">", gt, f32);
+        reg_op!(lib, ">=", gte, f32);
+        reg_op!(lib, "==", eq, f32);
+        reg_op!(lib, "!=", ne, f32);
     }
 
-    // `&&` and `||` are treated specially as they short-circuit.
-    // They are implemented as special `Expr` instances, not function calls.
-    //reg_op!(lib, "||", or, bool);
-    //reg_op!(lib, "&&", and, bool);
-
-    lib.set_fn_2("|", or);
-    lib.set_fn_2("&", and);
     lib.set_fn_1("!", not);
 });

src/packages/map_basic.rs

@@ -4,12 +4,9 @@ use crate::any::Dynamic;
 use crate::def_package;
 use crate::engine::Map;
 use crate::module::FuncReturn;
-use crate::parser::INT;
+use crate::parser::{ImmutableString, INT};
 
-use crate::stdlib::{
-    string::{String, ToString},
-    vec::Vec,
-};
+use crate::stdlib::{string::ToString, vec::Vec};
 
 fn map_get_keys(map: &mut Map) -> FuncReturn<Vec<Dynamic>> {
     Ok(map.iter().map(|(k, _)| k.to_string().into()).collect())
@@ -22,7 +19,7 @@ fn map_get_values(map: &mut Map) -> FuncReturn<Vec<Dynamic>> {
 def_package!(crate:BasicMapPackage:"Basic object map utilities.", lib, {
     lib.set_fn_2_mut(
         "has",
-        |map: &mut Map, prop: String| Ok(map.contains_key(&prop)),
+        |map: &mut Map, prop: ImmutableString| Ok(map.contains_key(prop.as_str())),
     );
     lib.set_fn_1_mut("len", |map: &mut Map| Ok(map.len() as INT));
     lib.set_fn_1_mut("clear", |map: &mut Map| {
@@ -31,7 +28,7 @@ def_package!(crate:BasicMapPackage:"Basic object map utilities.", lib, {
     });
     lib.set_fn_2_mut(
         "remove",
-        |x: &mut Map, name: String| Ok(x.remove(&name).unwrap_or_else(|| ().into())),
+        |x: &mut Map, name: ImmutableString| Ok(x.remove(name.as_str()).unwrap_or_else(|| ().into())),
     );
     lib.set_fn_2_mut(
         "mixin",
@@ -42,6 +39,15 @@ def_package!(crate:BasicMapPackage:"Basic object map utilities.", lib, {
             Ok(())
         },
     );
+    lib.set_fn_2_mut(
+        "+=",
+        |map1: &mut Map, map2: Map| {
+            map2.into_iter().for_each(|(key, value)| {
+                map1.insert(key, value);
+            });
+            Ok(())
+        },
+    );
     lib.set_fn_2(
         "+",
         |mut map1: Map, map2: Map| {

src/packages/math_basic.rs

@@ -43,6 +43,18 @@ def_package!(crate:BasicMathPackage:"Basic mathematic functions.", lib, {
         lib.set_fn_1("is_finite", |x: FLOAT| Ok(x.is_finite()));
         lib.set_fn_1("is_infinite", |x: FLOAT| Ok(x.is_infinite()));
 
+        #[cfg(not(feature = "no_object"))]
+        {
+            lib.set_getter_fn("floor", |x: &mut FLOAT| Ok(x.floor()));
+            lib.set_getter_fn("ceiling", |x: &mut FLOAT| Ok(x.ceil()));
+            lib.set_getter_fn("round", |x: &mut FLOAT| Ok(x.ceil()));
+            lib.set_getter_fn("int", |x: &mut FLOAT| Ok(x.trunc()));
+            lib.set_getter_fn("fraction", |x: &mut FLOAT| Ok(x.fract()));
+            lib.set_getter_fn("is_nan", |x: &mut FLOAT| Ok(x.is_nan()));
+            lib.set_getter_fn("is_finite", |x: &mut FLOAT| Ok(x.is_finite()));
+            lib.set_getter_fn("is_infinite", |x: &mut FLOAT| Ok(x.is_infinite()));
+        }
+
         // Register conversion functions
         lib.set_fn_1("to_float", |x: INT| Ok(x as FLOAT));
         lib.set_fn_1("to_float", |x: f32| Ok(x as FLOAT));

src/packages/mod.rs

@@ -1,13 +1,14 @@
 //! Module containing all built-in _packages_ available to Rhai, plus facilities to define custom packages.
 
-use crate::fn_native::{NativeCallable, SharedIteratorFunction};
+use crate::fn_native::{CallableFunction, IteratorFn, Shared};
 use crate::module::Module;
 use crate::utils::StaticVec;
 
-use crate::stdlib::{any::TypeId, boxed::Box, collections::HashMap, rc::Rc, sync::Arc, vec::Vec};
+use crate::stdlib::any::TypeId;
 
-mod arithmetic;
+pub(crate) mod arithmetic;
 mod array_basic;
+mod eval;
 mod iter_basic;
 mod logic;
 mod map_basic;
@@ -21,6 +22,7 @@ mod time_basic;
 pub use arithmetic::ArithmeticPackage;
 #[cfg(not(feature = "no_index"))]
 pub use array_basic::BasicArrayPackage;
+pub use eval::EvalPackage;
 pub use iter_basic::BasicIteratorPackage;
 pub use logic::LogicPackage;
 #[cfg(not(feature = "no_object"))]
@@ -42,35 +44,27 @@ pub trait Package {
     fn get(&self) -> PackageLibrary;
 }
 
-/// Type which `Rc`-wraps a `Module` to facilitate sharing library instances.
-#[cfg(not(feature = "sync"))]
-pub type PackageLibrary = Rc<Module>;
-
-/// Type which `Arc`-wraps a `Module` to facilitate sharing library instances.
-#[cfg(feature = "sync")]
-pub type PackageLibrary = Arc<Module>;
+/// A sharable `Module` to facilitate sharing library instances.
+pub type PackageLibrary = Shared<Module>;
 
 /// Type containing a collection of `PackageLibrary` instances.
 /// All function and type iterator keys in the loaded packages are indexed for fast access.
 #[derive(Clone, Default)]
-pub(crate) struct PackagesCollection {
-    /// Collection of `PackageLibrary` instances.
-    packages: StaticVec<PackageLibrary>,
-}
+pub(crate) struct PackagesCollection(StaticVec<PackageLibrary>);
 
 impl PackagesCollection {
     /// Add a `PackageLibrary` into the `PackagesCollection`.
     pub fn push(&mut self, package: PackageLibrary) {
         // Later packages override previous ones.
-        self.packages.insert(0, package);
+        self.0.insert(0, package);
     }
     /// Does the specified function hash key exist in the `PackagesCollection`?
     pub fn contains_fn(&self, hash: u64) -> bool {
-        self.packages.iter().any(|p| p.contains_fn(hash))
+        self.0.iter().any(|p| p.contains_fn(hash))
     }
     /// Get specified function via its hash key.
-    pub fn get_fn(&self, hash: u64) -> Option<&Box<dyn NativeCallable>> {
-        self.packages
+    pub fn get_fn(&self, hash: u64) -> Option<&CallableFunction> {
+        self.0
             .iter()
             .map(|p| p.get_fn(hash))
             .find(|f| f.is_some())
@@ -78,11 +72,11 @@ impl PackagesCollection {
     }
     /// Does the specified TypeId iterator exist in the `PackagesCollection`?
     pub fn contains_iter(&self, id: TypeId) -> bool {
-        self.packages.iter().any(|p| p.contains_iter(id))
+        self.0.iter().any(|p| p.contains_iter(id))
     }
     /// Get the specified TypeId iterator.
-    pub fn get_iter(&self, id: TypeId) -> Option<&SharedIteratorFunction> {
-        self.packages
+    pub fn get_iter(&self, id: TypeId) -> Option<IteratorFn> {
+        self.0
             .iter()
             .map(|p| p.get_iter(id))
             .find(|f| f.is_some())

src/packages/string_basic.rs

@@ -1,7 +1,7 @@
 use crate::def_package;
 use crate::engine::{FUNC_TO_STRING, KEYWORD_DEBUG, KEYWORD_PRINT};
 use crate::module::FuncReturn;
-use crate::parser::INT;
+use crate::parser::{ImmutableString, INT};
 
 #[cfg(not(feature = "no_index"))]
 use crate::engine::Array;
@@ -12,19 +12,19 @@ use crate::engine::Map;
 use crate::stdlib::{
     fmt::{Debug, Display},
     format,
-    string::{String, ToString},
+    string::ToString,
 };
 
 // Register print and debug
-fn to_debug<T: Debug>(x: &mut T) -> FuncReturn<String> {
-    Ok(format!("{:?}", x))
+fn to_debug<T: Debug>(x: &mut T) -> FuncReturn<ImmutableString> {
+    Ok(format!("{:?}", x).into())
 }
-fn to_string<T: Display>(x: &mut T) -> FuncReturn<String> {
-    Ok(format!("{}", x))
+fn to_string<T: Display>(x: &mut T) -> FuncReturn<ImmutableString> {
+    Ok(format!("{}", x).into())
 }
 #[cfg(not(feature = "no_object"))]
-fn format_map(x: &mut Map) -> FuncReturn<String> {
-    Ok(format!("#{:?}", x))
+fn format_map(x: &mut Map) -> FuncReturn<ImmutableString> {
+    Ok(format!("#{:?}", x).into())
 }
 
 macro_rules! reg_op {
@@ -41,10 +41,10 @@ def_package!(crate:BasicStringPackage:"Basic string utilities, including printin
     lib.set_fn_1(KEYWORD_PRINT, |_: ()| Ok("".to_string()));
     lib.set_fn_1(FUNC_TO_STRING, |_: ()| Ok("".to_string()));
 
-    lib.set_fn_1_mut(KEYWORD_PRINT, |s: &mut String| Ok(s.clone()));
-    lib.set_fn_1_mut(FUNC_TO_STRING, |s: &mut String| Ok(s.clone()));
+    lib.set_fn_1(KEYWORD_PRINT, |s: ImmutableString| Ok(s));
+    lib.set_fn_1(FUNC_TO_STRING, |s: ImmutableString| Ok(s));
 
-    reg_op!(lib, KEYWORD_DEBUG, to_debug, INT, bool, (), char, String);
+    reg_op!(lib, KEYWORD_DEBUG, to_debug, INT, bool, (), char, ImmutableString);
 
     #[cfg(not(feature = "only_i32"))]
     #[cfg(not(feature = "only_i64"))]
@@ -78,29 +78,8 @@ def_package!(crate:BasicStringPackage:"Basic string utilities, including printin
         lib.set_fn_1_mut(KEYWORD_DEBUG, format_map);
     }
 
-    lib.set_fn_2(
-        "+",
-        |mut s: String, ch: char| {
-            s.push(ch);
-            Ok(s)
-        },
-    );
-    lib.set_fn_2(
-        "+",
-        |mut s: String, s2: String| {
-            s.push_str(&s2);
-            Ok(s)
-        },
-    );
-    lib.set_fn_2_mut("append", |s: &mut String, ch: char| {
-        s.push(ch);
-        Ok(())
-    });
-    lib.set_fn_2_mut(
-        "append",
-        |s: &mut String, s2: String| {
-            s.push_str(&s2);
-            Ok(())
-        }
-    );
+    lib.set_fn_2("+", |s: ImmutableString, ch: char| Ok(s + ch));
+    lib.set_fn_2_mut("+=", |s: &mut ImmutableString, ch: char| { *s += ch; Ok(()) });
+    lib.set_fn_2_mut("append", |s: &mut ImmutableString, ch: char| { *s += ch; Ok(()) });
+    lib.set_fn_2_mut("append", |s: &mut ImmutableString, s2: ImmutableString| { *s += &s2; Ok(()) });
 });

src/packages/string_more.rs

@@ -1,6 +1,6 @@
 use crate::def_package;
 use crate::module::FuncReturn;
-use crate::parser::INT;
+use crate::parser::{ImmutableString, INT};
 use crate::utils::StaticVec;
 
 #[cfg(not(feature = "no_index"))]
@@ -10,22 +10,21 @@ use crate::stdlib::{
     fmt::Display,
     format,
     string::{String, ToString},
-    vec::Vec,
 };
 
-fn prepend<T: Display>(x: T, y: String) -> FuncReturn<String> {
-    Ok(format!("{}{}", x, y))
+fn prepend<T: Display>(x: T, y: ImmutableString) -> FuncReturn<ImmutableString> {
+    Ok(format!("{}{}", x, y).into())
 }
-fn append<T: Display>(x: String, y: T) -> FuncReturn<String> {
-    Ok(format!("{}{}", x, y))
+fn append<T: Display>(x: ImmutableString, y: T) -> FuncReturn<ImmutableString> {
+    Ok(format!("{}{}", x, y).into())
 }
-fn sub_string(s: &mut String, start: INT, len: INT) -> FuncReturn<String> {
+fn sub_string(s: ImmutableString, start: INT, len: INT) -> FuncReturn<ImmutableString> {
     let offset = if s.is_empty() || len <= 0 {
-        return Ok("".to_string());
+        return Ok("".to_string().into());
     } else if start < 0 {
         0
     } else if (start as usize) >= s.chars().count() {
-        return Ok("".to_string());
+        return Ok("".to_string().into());
     } else {
         start as usize
     };
@@ -38,36 +37,38 @@ fn sub_string(s: &mut String, start: INT, len: INT) -> FuncReturn<String> {
         len as usize
     };
 
-    Ok(chars.iter().skip(offset).take(len).cloned().collect())
-}
-fn crop_string(s: &mut String, start: INT, len: INT) -> FuncReturn<()> {
-    let offset = if s.is_empty() || len <= 0 {
-        s.clear();
-        return Ok(());
-    } else if start < 0 {
-        0
-    } else if (start as usize) >= s.chars().count() {
-        s.clear();
-        return Ok(());
-    } else {
-        start as usize
-    };
-
-    let chars: StaticVec<_> = s.chars().collect();
-
-    let len = if offset + (len as usize) > chars.len() {
-        chars.len() - offset
-    } else {
-        len as usize
-    };
-
-    s.clear();
-
-    chars
+    Ok(chars
         .iter()
         .skip(offset)
         .take(len)
-        .for_each(|&ch| s.push(ch));
+        .cloned()
+        .collect::<String>()
+        .into())
+}
+fn crop_string(s: &mut ImmutableString, start: INT, len: INT) -> FuncReturn<()> {
+    let offset = if s.is_empty() || len <= 0 {
+        s.make_mut().clear();
+        return Ok(());
+    } else if start < 0 {
+        0
+    } else if (start as usize) >= s.chars().count() {
+        s.make_mut().clear();
+        return Ok(());
+    } else {
+        start as usize
+    };
+
+    let chars: StaticVec<_> = s.chars().collect();
+
+    let len = if offset + (len as usize) > chars.len() {
+        chars.len() - offset
+    } else {
+        len as usize
+    };
+
+    let copy = s.make_mut();
+    copy.clear();
+    copy.extend(chars.iter().skip(offset).take(len));
 
     Ok(())
 }
@@ -80,10 +81,10 @@ macro_rules! reg_op {
 
 def_package!(crate:MoreStringPackage:"Additional string utilities, including string building.", lib, {
     reg_op!(lib, "+", append, INT, bool, char);
-    lib.set_fn_2_mut( "+", |x: &mut String, _: ()| Ok(x.clone()));
+    lib.set_fn_2( "+", |x: ImmutableString, _: ()| Ok(x));
 
     reg_op!(lib, "+", prepend, INT, bool, char);
-    lib.set_fn_2("+", |_: (), y: String| Ok(y));
+    lib.set_fn_2("+", |_: (), y: ImmutableString| Ok(y));
 
     #[cfg(not(feature = "only_i32"))]
     #[cfg(not(feature = "only_i64"))]
@@ -100,22 +101,26 @@ def_package!(crate:MoreStringPackage:"Additional string utilities, including str
 
     #[cfg(not(feature = "no_index"))]
     {
-        lib.set_fn_2("+", |x: String, y: Array| Ok(format!("{}{:?}", x, y)));
-        lib.set_fn_2("+", |x: Array, y: String| Ok(format!("{:?}{}", x, y)));
+        lib.set_fn_2_mut("+", |x: &mut ImmutableString, y: Array| Ok(format!("{}{:?}", x, y)));
+        lib.set_fn_2_mut("+", |x: &mut Array, y: ImmutableString| Ok(format!("{:?}{}", x, y)));
     }
 
-    lib.set_fn_1_mut("len", |s: &mut String| Ok(s.chars().count() as INT));
+    lib.set_fn_1_mut("len", |s: &mut ImmutableString| Ok(s.chars().count() as INT));
+
+    #[cfg(not(feature = "no_object"))]
+    lib.set_getter_fn("len", |s: &mut ImmutableString| Ok(s.chars().count() as INT));
+
     lib.set_fn_2_mut(
         "contains",
-        |s: &mut String, ch: char| Ok(s.contains(ch)),
+        |s: &mut ImmutableString, ch: char| Ok(s.contains(ch)),
     );
     lib.set_fn_2_mut(
         "contains",
-        |s: &mut String, find: String| Ok(s.contains(&find)),
+        |s: &mut ImmutableString, find: ImmutableString| Ok(s.contains(find.as_str())),
     );
     lib.set_fn_3_mut(
         "index_of",
-        |s: &mut String, ch: char, start: INT| {
+        |s: &mut ImmutableString, ch: char, start: INT| {
             let start = if start < 0 {
                 0
             } else if (start as usize) >= s.chars().count() {
@@ -132,7 +137,7 @@ def_package!(crate:MoreStringPackage:"Additional string utilities, including str
     );
     lib.set_fn_2_mut(
         "index_of",
-        |s: &mut String, ch: char| {
+        |s: &mut ImmutableString, ch: char| {
             Ok(s.find(ch)
                 .map(|index| s[0..index].chars().count() as INT)
                 .unwrap_or(-1 as INT))
@@ -140,7 +145,7 @@ def_package!(crate:MoreStringPackage:"Additional string utilities, including str
     );
     lib.set_fn_3_mut(
         "index_of",
-        |s: &mut String, find: String, start: INT| {
+        |s: &mut ImmutableString, find: ImmutableString, start: INT| {
             let start = if start < 0 {
                 0
             } else if (start as usize) >= s.chars().count() {
@@ -150,109 +155,106 @@ def_package!(crate:MoreStringPackage:"Additional string utilities, including str
             };
 
             Ok(s[start..]
-                .find(&find)
+                .find(find.as_str())
                 .map(|index| s[0..start + index].chars().count() as INT)
                 .unwrap_or(-1 as INT))
         },
     );
     lib.set_fn_2_mut(
         "index_of",
-        |s: &mut String, find: String| {
-            Ok(s.find(&find)
+        |s: &mut ImmutableString, find: ImmutableString| {
+            Ok(s.find(find.as_str())
                 .map(|index| s[0..index].chars().count() as INT)
                 .unwrap_or(-1 as INT))
         },
     );
-    lib.set_fn_1_mut("clear", |s: &mut String| {
-        s.clear();
+    lib.set_fn_1_mut("clear", |s: &mut ImmutableString| {
+        s.make_mut().clear();
         Ok(())
     });
-    lib.set_fn_2_mut( "append", |s: &mut String, ch: char| {
-        s.push(ch);
+    lib.set_fn_2_mut("append", |s: &mut ImmutableString, ch: char| {
+        s.make_mut().push(ch);
         Ok(())
     });
     lib.set_fn_2_mut(
         "append",
-        |s: &mut String, add: String| {
-            s.push_str(&add);
+        |s: &mut ImmutableString, add: ImmutableString| {
+            s.make_mut().push_str(add.as_str());
             Ok(())
         }
     );
-    lib.set_fn_3_mut( "sub_string", sub_string);
-    lib.set_fn_2_mut(
+    lib.set_fn_3("sub_string", sub_string);
+    lib.set_fn_2(
         "sub_string",
-        |s: &mut String, start: INT| sub_string(s, start, s.len() as INT),
+        |s: ImmutableString, start: INT| {
+            let len = s.len() as INT;
+            sub_string(s, start, len)
+        },
     );
-    lib.set_fn_3_mut( "crop", crop_string);
+    lib.set_fn_3_mut("crop", crop_string);
     lib.set_fn_2_mut(
         "crop",
-        |s: &mut String, start: INT| crop_string(s, start, s.len() as INT),
+        |s: &mut ImmutableString, start: INT| crop_string(s, start, s.len() as INT),
     );
     lib.set_fn_2_mut(
         "truncate",
-        |s: &mut String, len: INT| {
-            if len >= 0 {
-                let chars: StaticVec<_> = s.chars().take(len as usize).collect();
-                s.clear();
-                chars.iter().for_each(|&ch| s.push(ch));
+        |s: &mut ImmutableString, len: INT| {
+            if len > 0 {
+                let chars: StaticVec<_> = s.chars().collect();
+                let copy = s.make_mut();
+                copy.clear();
+                copy.extend(chars.into_iter().take(len as usize));
             } else {
-                s.clear();
+                s.make_mut().clear();
             }
             Ok(())
         },
     );
     lib.set_fn_3_mut(
         "pad",
-        |s: &mut String, len: INT, ch: char| {
-            for _ in 0..s.chars().count() - len as usize {
-                s.push(ch);
+        |s: &mut ImmutableString, len: INT, ch: char| {
+            let copy = s.make_mut();
+            for _ in 0..copy.chars().count() - len as usize {
+                copy.push(ch);
             }
             Ok(())
         },
     );
     lib.set_fn_3_mut(
         "replace",
-        |s: &mut String, find: String, sub: String| {
-            let new_str = s.replace(&find, &sub);
-            s.clear();
-            s.push_str(&new_str);
+        |s: &mut ImmutableString, find: ImmutableString, sub: ImmutableString| {
+            *s = s.replace(find.as_str(), sub.as_str()).into();
             Ok(())
         },
     );
     lib.set_fn_3_mut(
         "replace",
-        |s: &mut String, find: String, sub: char| {
-            let new_str = s.replace(&find, &sub.to_string());
-            s.clear();
-            s.push_str(&new_str);
+        |s: &mut ImmutableString, find: ImmutableString, sub: char| {
+            *s = s.replace(find.as_str(), &sub.to_string()).into();
             Ok(())
         },
     );
     lib.set_fn_3_mut(
         "replace",
-        |s: &mut String, find: char, sub: String| {
-            let new_str = s.replace(&find.to_string(), &sub);
-            s.clear();
-            s.push_str(&new_str);
+        |s: &mut ImmutableString, find: char, sub: ImmutableString| {
+            *s = s.replace(&find.to_string(), sub.as_str()).into();
             Ok(())
         },
     );
     lib.set_fn_3_mut(
         "replace",
-        |s: &mut String, find: char, sub: char| {
-            let new_str = s.replace(&find.to_string(), &sub.to_string());
-            s.clear();
-            s.push_str(&new_str);
+        |s: &mut ImmutableString, find: char, sub: char| {
+            *s = s.replace(&find.to_string(), &sub.to_string()).into();
             Ok(())
         },
     );
     lib.set_fn_1_mut(
         "trim",
-        |s: &mut String| {
+        |s: &mut ImmutableString| {
             let trimmed = s.trim();
 
             if trimmed.len() < s.len() {
-                *s = trimmed.to_string();
+                *s = trimmed.to_string().into();
             }
             Ok(())
         },

src/packages/time_basic.rs

@@ -10,6 +10,9 @@ use crate::token::Position;
 #[cfg(not(feature = "no_std"))]
 use crate::stdlib::time::Instant;
 
+#[cfg(not(feature = "no_float"))]
+use crate::parser::FLOAT;
+
 #[cfg(not(feature = "no_std"))]
 def_package!(crate:BasicTimePackage:"Basic timing utilities.", lib, {
     // Register date/time functions
@@ -70,27 +73,29 @@ def_package!(crate:BasicTimePackage:"Basic timing utilities.", lib, {
     lib.set_fn_2("==", eq::<Instant>);
     lib.set_fn_2("!=", ne::<Instant>);
 
-    lib.set_fn_1(
-        "elapsed",
-        |timestamp: Instant| {
-            #[cfg(not(feature = "no_float"))]
-            return Ok(timestamp.elapsed().as_secs_f64());
+    #[cfg(not(feature = "no_float"))]
+    fn elapsed (timestamp: &mut Instant) -> Result<FLOAT, Box<EvalAltResult>> {
+        Ok(timestamp.elapsed().as_secs_f64())
+    }
 
-            #[cfg(feature = "no_float")]
-            {
-                let seconds = timestamp.elapsed().as_secs();
+    #[cfg(feature = "no_float")]
+    fn elapsed (timestamp: &mut Instant) -> Result<INT, Box<EvalAltResult>> {
+        let seconds = timestamp.elapsed().as_secs();
 
-                #[cfg(not(feature = "unchecked"))]
-                {
-                    if seconds > (MAX_INT as u64) {
-                        return Err(Box::new(EvalAltResult::ErrorArithmetic(
-                            format!("Integer overflow for timestamp.elapsed(): {}", seconds),
-                            Position::none(),
-                        )));
-                    }
-                }
-                return Ok(seconds as INT);
+        #[cfg(not(feature = "unchecked"))]
+        {
+            if seconds > (MAX_INT as u64) {
+                return Err(Box::new(EvalAltResult::ErrorArithmetic(
+                    format!("Integer overflow for timestamp.elapsed: {}", seconds),
+                    Position::none(),
+                )));
             }
-        },
-    );
+        }
+        Ok(seconds as INT)
+    }
+
+    lib.set_fn_1_mut("elapsed", elapsed);
+
+    #[cfg(not(feature = "no_object"))]
+    lib.set_getter_fn("elapsed", elapsed);
 });

src/result.rs

@@ -23,7 +23,7 @@ use crate::stdlib::path::PathBuf;
 #[derive(Debug)]
 pub enum EvalAltResult {
     /// Syntax error.
-    ErrorParsing(Box<ParseError>),
+    ErrorParsing(ParseError),
 
     /// Error reading from a script file. Wrapped value is the path of the script file.
     ///
@@ -36,10 +36,6 @@ pub enum EvalAltResult {
     /// An error has occurred inside a called function.
     /// Wrapped values re the name of the function and the interior error.
     ErrorInFunctionCall(String, Box<EvalAltResult>, Position),
-    /// Function call has incorrect number of arguments.
-    /// Wrapped values are the name of the function, the number of parameters required
-    /// and the actual number of arguments passed.
-    ErrorFunctionArgsMismatch(String, usize, usize, Position),
     /// Non-boolean operand encountered for boolean operator. Wrapped value is the operator.
     ErrorBooleanArgMismatch(String, Position),
     /// Non-character value encountered where a character is required.
@@ -108,9 +104,6 @@ impl EvalAltResult {
             Self::ErrorParsing(p) => p.desc(),
             Self::ErrorInFunctionCall(_, _, _) => "Error in called function",
             Self::ErrorFunctionNotFound(_, _) => "Function not found",
-            Self::ErrorFunctionArgsMismatch(_, _, _, _) => {
-                "Function call with wrong number of arguments"
-            }
             Self::ErrorBooleanArgMismatch(_, _) => "Boolean operator expects boolean operands",
             Self::ErrorCharMismatch(_) => "Character expected",
             Self::ErrorNumericIndexExpr(_) => {
@@ -208,21 +201,6 @@ impl fmt::Display for EvalAltResult {
             Self::ErrorLoopBreak(_, pos) => write!(f, "{} ({})", desc, pos),
             Self::Return(_, pos) => write!(f, "{} ({})", desc, pos),
 
-            Self::ErrorFunctionArgsMismatch(fn_name, 0, n, pos) => write!(
-                f,
-                "Function '{}' expects no argument but {} found ({})",
-                fn_name, n, pos
-            ),
-            Self::ErrorFunctionArgsMismatch(fn_name, 1, n, pos) => write!(
-                f,
-                "Function '{}' expects one argument but {} found ({})",
-                fn_name, n, pos
-            ),
-            Self::ErrorFunctionArgsMismatch(fn_name, need, n, pos) => write!(
-                f,
-                "Function '{}' expects {} argument(s) but {} found ({})",
-                fn_name, need, n, pos
-            ),
             Self::ErrorBooleanArgMismatch(op, pos) => {
                 write!(f, "{} operator expects boolean operands ({})", op, pos)
             }
@@ -263,11 +241,6 @@ impl fmt::Display for EvalAltResult {
 
 impl From<ParseError> for Box<EvalAltResult> {
     fn from(err: ParseError) -> Self {
-        Box::new(EvalAltResult::ErrorParsing(Box::new(err)))
-    }
-}
-impl From<Box<ParseError>> for Box<EvalAltResult> {
-    fn from(err: Box<ParseError>) -> Self {
         Box::new(EvalAltResult::ErrorParsing(err))
     }
 }
@@ -292,7 +265,6 @@ impl EvalAltResult {
 
             Self::ErrorFunctionNotFound(_, pos)
             | Self::ErrorInFunctionCall(_, _, pos)
-            | Self::ErrorFunctionArgsMismatch(_, _, _, pos)
             | Self::ErrorBooleanArgMismatch(_, pos)
             | Self::ErrorCharMismatch(pos)
             | Self::ErrorArrayBounds(_, _, pos)
@@ -331,7 +303,6 @@ impl EvalAltResult {
 
             Self::ErrorFunctionNotFound(_, pos)
             | Self::ErrorInFunctionCall(_, _, pos)
-            | Self::ErrorFunctionArgsMismatch(_, _, _, pos)
             | Self::ErrorBooleanArgMismatch(_, pos)
             | Self::ErrorCharMismatch(pos)
             | Self::ErrorArrayBounds(_, _, pos)

src/token.rs

@@ -21,8 +21,8 @@ type LERR = LexError;
 
 /// A location (line number + character position) in the input script.
 ///
-/// In order to keep footprint small, both line number and character position have 16-bit resolution,
-/// meaning they go up to a maximum of 65,535 lines/characters per line.
+/// In order to keep footprint small, both line number and character position have 16-bit unsigned resolution,
+/// meaning they go up to a maximum of 65,535 lines and characters per line.
 /// Advancing beyond the maximum line length or maximum number of lines is not an error but has no effect.
 #[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy)]
 pub struct Position {

src/unsafe.rs

@@ -42,6 +42,18 @@ pub fn unsafe_cast_box<X: Variant, T: Variant>(item: Box<X>) -> Result<Box<T>, B
     }
 }
 
+/// # DANGEROUS!!!
+///
+/// A dangerous function that blindly casts a reference from one lifetime to another lifetime.
+///
+/// Force-casting a a reference to another lifetime saves on allocations and string cloning,
+/// but must be used with the utmost care.
+pub fn unsafe_mut_cast_to_lifetime<'a, T>(value: &mut T) -> &'a mut T {
+    unsafe { mem::transmute::<_, &'a mut T>(value) }
+}
+
+/// # DANGEROUS!!!
+///
 /// A dangerous function that blindly casts a `&str` from one lifetime to a `Cow<str>` of
 /// another lifetime.  This is mainly used to let us push a block-local variable into the
 /// current `Scope` without cloning the variable name.  Doing this is safe because all local

src/utils.rs

@@ -4,14 +4,20 @@
 //!
 //! The `StaticVec` type has some `unsafe` blocks to handle conversions between `MaybeUninit` and regular types.
 
+use crate::fn_native::{shared_make_mut, shared_take, Shared};
+
 use crate::stdlib::{
     any::TypeId,
+    borrow::Borrow,
+    boxed::Box,
     fmt,
-    hash::{Hash, Hasher},
+    hash::{BuildHasher, Hash, Hasher},
     iter::FromIterator,
     mem,
     mem::MaybeUninit,
-    ops::{Drop, Index, IndexMut},
+    ops::{Add, AddAssign, Deref, Drop, Index, IndexMut},
+    str::FromStr,
+    string::{String, ToString},
     vec::Vec,
 };
 
@@ -21,9 +27,46 @@ use crate::stdlib::collections::hash_map::DefaultHasher;
 #[cfg(feature = "no_std")]
 use ahash::AHasher;
 
-#[inline(always)]
-pub fn EMPTY_TYPE_ID() -> TypeId {
-    TypeId::of::<()>()
+/// A hasher that only takes one single `u64` and returns it as a hash key.
+///
+/// # Panics
+///
+/// Panics when hashing any data type other than a `u64`.
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash, Default)]
+pub struct StraightHasher(u64);
+
+impl Hasher for StraightHasher {
+    #[inline(always)]
+    fn finish(&self) -> u64 {
+        self.0
+    }
+    #[inline]
+    fn write(&mut self, bytes: &[u8]) {
+        let mut key = [0_u8; 8];
+        key.copy_from_slice(&bytes[..8]); // Panics if fewer than 8 bytes
+        self.0 = u64::from_le_bytes(key);
+    }
+}
+
+impl StraightHasher {
+    /// Create a `StraightHasher`.
+    #[inline(always)]
+    pub fn new() -> Self {
+        Self(0)
+    }
+}
+
+/// A hash builder for `StraightHasher`.
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash, Default)]
+pub struct StraightHasherBuilder;
+
+impl BuildHasher for StraightHasherBuilder {
+    type Hasher = StraightHasher;
+
+    #[inline(always)]
+    fn build_hasher(&self) -> Self::Hasher {
+        StraightHasher::new()
+    }
 }
 
 /// Calculate a `u64` hash key from a module-qualified function name and parameter types.
@@ -37,6 +80,7 @@ pub fn EMPTY_TYPE_ID() -> TypeId {
 pub fn calc_fn_spec<'a>(
     modules: impl Iterator<Item = &'a str>,
     fn_name: &str,
+    num: usize,
     params: impl Iterator<Item = TypeId>,
 ) -> u64 {
     #[cfg(feature = "no_std")]
@@ -47,6 +91,7 @@ pub fn calc_fn_spec<'a>(
     // We always skip the first module
     modules.skip(1).for_each(|m| m.hash(&mut s));
     s.write(fn_name.as_bytes());
+    s.write_usize(num);
     params.for_each(|t| t.hash(&mut s));
     s.finish()
 }
@@ -105,6 +150,7 @@ pub struct StaticVec<T> {
 const MAX_STATIC_VEC: usize = 4;
 
 impl<T> Drop for StaticVec<T> {
+    #[inline(always)]
     fn drop(&mut self) {
         self.clear();
     }
@@ -171,6 +217,7 @@ impl<T> FromIterator<T> for StaticVec<T> {
 
 impl<T> StaticVec<T> {
     /// Create a new `StaticVec`.
+    #[inline(always)]
     pub fn new() -> Self {
         Default::default()
     }
@@ -186,6 +233,7 @@ impl<T> StaticVec<T> {
         self.len = 0;
     }
     /// Extract a `MaybeUninit` into a concrete initialized type.
+    #[inline(always)]
     fn extract(value: MaybeUninit<T>) -> T {
         unsafe { value.assume_init() }
     }
@@ -247,6 +295,7 @@ impl<T> StaticVec<T> {
         );
     }
     /// Is data stored in fixed-size storage?
+    #[inline(always)]
     fn is_fixed_storage(&self) -> bool {
         self.len <= MAX_STATIC_VEC
     }
@@ -356,10 +405,12 @@ impl<T> StaticVec<T> {
         result
     }
     /// Get the number of items in this `StaticVec`.
+    #[inline(always)]
     pub fn len(&self) -> usize {
         self.len
     }
     /// Is this `StaticVec` empty?
+    #[inline(always)]
     pub fn is_empty(&self) -> bool {
         self.len == 0
     }
@@ -563,3 +614,289 @@ impl<T> From<Vec<T>> for StaticVec<T> {
         arr
     }
 }
+
+/// The system immutable string type.
+///
+/// An `ImmutableString` wraps an `Rc<String>` (or `Arc<String>` under the `sync` feature)
+/// so that it can be simply shared and not cloned.
+///
+/// # Examples
+///
+/// ```
+/// use rhai::ImmutableString;
+///
+/// let s1: ImmutableString = "hello".into();
+///
+/// // No actual cloning of the string is involved below.
+/// let s2 = s1.clone();
+/// let s3 = s2.clone();
+///
+/// assert_eq!(s1, s2);
+///
+/// // Clones the underlying string (because it is already shared) and extracts it.
+/// let mut s: String = s1.into_owned();
+///
+/// // Changing the clone has no impact on the previously shared version.
+/// s.push_str(", world!");
+///
+/// // The old version still exists.
+/// assert_eq!(s2, s3);
+/// assert_eq!(s2.as_str(), "hello");
+///
+/// // Not equals!
+/// assert_ne!(s2.as_str(), s.as_str());
+/// assert_eq!(s, "hello, world!");
+/// ```
+#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Default)]
+pub struct ImmutableString(Shared<String>);
+
+impl Deref for ImmutableString {
+    type Target = String;
+
+    #[inline(always)]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl AsRef<String> for ImmutableString {
+    #[inline(always)]
+    fn as_ref(&self) -> &String {
+        &self.0
+    }
+}
+
+impl Borrow<str> for ImmutableString {
+    #[inline(always)]
+    fn borrow(&self) -> &str {
+        self.0.as_str()
+    }
+}
+
+impl From<&str> for ImmutableString {
+    #[inline(always)]
+    fn from(value: &str) -> Self {
+        Self(value.to_string().into())
+    }
+}
+impl From<String> for ImmutableString {
+    #[inline(always)]
+    fn from(value: String) -> Self {
+        Self(value.into())
+    }
+}
+
+impl From<Box<String>> for ImmutableString {
+    #[inline(always)]
+    fn from(value: Box<String>) -> Self {
+        Self(value.into())
+    }
+}
+
+impl From<ImmutableString> for String {
+    #[inline(always)]
+    fn from(value: ImmutableString) -> Self {
+        value.into_owned()
+    }
+}
+
+impl FromStr for ImmutableString {
+    type Err = ();
+
+    #[inline(always)]
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(Self(s.to_string().into()))
+    }
+}
+
+impl FromIterator<char> for ImmutableString {
+    #[inline(always)]
+    fn from_iter<T: IntoIterator<Item = char>>(iter: T) -> Self {
+        Self(iter.into_iter().collect::<String>().into())
+    }
+}
+
+impl<'a> FromIterator<&'a char> for ImmutableString {
+    #[inline(always)]
+    fn from_iter<T: IntoIterator<Item = &'a char>>(iter: T) -> Self {
+        Self(iter.into_iter().cloned().collect::<String>().into())
+    }
+}
+
+impl<'a> FromIterator<&'a str> for ImmutableString {
+    #[inline(always)]
+    fn from_iter<T: IntoIterator<Item = &'a str>>(iter: T) -> Self {
+        Self(iter.into_iter().collect::<String>().into())
+    }
+}
+
+impl<'a> FromIterator<String> for ImmutableString {
+    #[inline(always)]
+    fn from_iter<T: IntoIterator<Item = String>>(iter: T) -> Self {
+        Self(iter.into_iter().collect::<String>().into())
+    }
+}
+
+impl fmt::Display for ImmutableString {
+    #[inline(always)]
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self.0.as_str(), f)
+    }
+}
+
+impl fmt::Debug for ImmutableString {
+    #[inline(always)]
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(self.0.as_str(), f)
+    }
+}
+
+impl Add for ImmutableString {
+    type Output = Self;
+
+    fn add(mut self, rhs: Self) -> Self::Output {
+        if rhs.is_empty() {
+            self
+        } else if self.is_empty() {
+            rhs
+        } else {
+            self.make_mut().push_str(rhs.0.as_str());
+            self
+        }
+    }
+}
+
+impl Add for &ImmutableString {
+    type Output = ImmutableString;
+
+    fn add(self, rhs: Self) -> Self::Output {
+        if rhs.is_empty() {
+            self.clone()
+        } else if self.is_empty() {
+            rhs.clone()
+        } else {
+            let mut s = self.clone();
+            s.make_mut().push_str(rhs.0.as_str());
+            s
+        }
+    }
+}
+
+impl AddAssign<&ImmutableString> for ImmutableString {
+    fn add_assign(&mut self, rhs: &ImmutableString) {
+        if !rhs.is_empty() {
+            if self.is_empty() {
+                self.0 = rhs.0.clone();
+            } else {
+                self.make_mut().push_str(rhs.0.as_str());
+            }
+        }
+    }
+}
+
+impl Add<&str> for ImmutableString {
+    type Output = Self;
+
+    fn add(mut self, rhs: &str) -> Self::Output {
+        if rhs.is_empty() {
+            self
+        } else {
+            self.make_mut().push_str(rhs);
+            self
+        }
+    }
+}
+
+impl Add<&str> for &ImmutableString {
+    type Output = ImmutableString;
+
+    fn add(self, rhs: &str) -> Self::Output {
+        if rhs.is_empty() {
+            self.clone()
+        } else {
+            let mut s = self.clone();
+            s.make_mut().push_str(rhs);
+            s
+        }
+    }
+}
+
+impl AddAssign<&str> for ImmutableString {
+    fn add_assign(&mut self, rhs: &str) {
+        if !rhs.is_empty() {
+            self.make_mut().push_str(rhs);
+        }
+    }
+}
+
+impl Add<String> for ImmutableString {
+    type Output = Self;
+
+    fn add(mut self, rhs: String) -> Self::Output {
+        if rhs.is_empty() {
+            self
+        } else if self.is_empty() {
+            rhs.into()
+        } else {
+            self.make_mut().push_str(&rhs);
+            self
+        }
+    }
+}
+
+impl Add<String> for &ImmutableString {
+    type Output = ImmutableString;
+
+    fn add(self, rhs: String) -> Self::Output {
+        if rhs.is_empty() {
+            self.clone()
+        } else if self.is_empty() {
+            rhs.into()
+        } else {
+            let mut s = self.clone();
+            s.make_mut().push_str(&rhs);
+            s
+        }
+    }
+}
+
+impl Add<char> for ImmutableString {
+    type Output = Self;
+
+    fn add(mut self, rhs: char) -> Self::Output {
+        self.make_mut().push(rhs);
+        self
+    }
+}
+
+impl Add<char> for &ImmutableString {
+    type Output = ImmutableString;
+
+    fn add(self, rhs: char) -> Self::Output {
+        let mut s = self.clone();
+        s.make_mut().push(rhs);
+        s
+    }
+}
+
+impl AddAssign<char> for ImmutableString {
+    #[inline(always)]
+    fn add_assign(&mut self, rhs: char) {
+        self.make_mut().push(rhs);
+    }
+}
+
+impl ImmutableString {
+    /// Consume the `ImmutableString` and convert it into a `String`.
+    /// If there are other references to the same string, a cloned copy is returned.
+    pub fn into_owned(mut self) -> String {
+        self.make_mut(); // Make sure it is unique reference
+        shared_take(self.0) // Should succeed
+    }
+    /// Make sure that the `ImmutableString` is unique (i.e. no other outstanding references).
+    /// Then return a mutable reference to the `String`.
+    #[inline(always)]
+    pub fn make_mut(&mut self) -> &mut String {
+        shared_make_mut(&mut self.0)
+    }
+}

tests/arrays.rs

@@ -26,7 +26,7 @@ fn test_arrays() -> Result<(), Box<EvalAltResult>> {
                 let y = [4, 5];
                 x.append(y);
 
-                x.len() + r
+                x.len + r
            "
         )?,
         14

tests/float.rs

@@ -22,7 +22,7 @@ fn test_float() -> Result<(), Box<EvalAltResult>> {
 
 #[test]
 #[cfg(not(feature = "no_object"))]
-fn struct_with_float() -> Result<(), Box<EvalAltResult>> {
+fn test_struct_with_float() -> Result<(), Box<EvalAltResult>> {
     #[derive(Clone)]
     struct TestStruct {
         x: f64,
@@ -64,3 +64,16 @@ fn struct_with_float() -> Result<(), Box<EvalAltResult>> {
 
     Ok(())
 }
+
+#[test]
+fn test_float_func() -> Result<(), Box<EvalAltResult>> {
+    let mut engine = Engine::new();
+
+    engine.register_fn("sum", |x: FLOAT, y: FLOAT, z: FLOAT, w: FLOAT| {
+        x + y + z + w
+    });
+
+    assert_eq!(engine.eval::<FLOAT>("sum(1.0, 2.0, 3.0, 4.0)")?, 10.0);
+
+    Ok(())
+}

tests/for.rs

@@ -48,7 +48,7 @@ fn test_for_object() -> Result<(), Box<EvalAltResult>> {
             sum += value;
         }
 
-        keys.len() + sum
+        keys.len + sum
     "#;
 
     assert_eq!(engine.eval::<INT>(script)?, 9);

tests/functions.rs

@@ -7,12 +7,23 @@ fn test_functions() -> Result<(), Box<EvalAltResult>> {
 
     assert_eq!(engine.eval::<INT>("fn add(x, n) { x + n } add(40, 2)")?, 42);
 
+    assert_eq!(
+        engine.eval::<INT>("fn add(x, n) { x + n } let a = 40; add(a, 2); a")?,
+        40
+    );
+
     #[cfg(not(feature = "no_object"))]
     assert_eq!(
         engine.eval::<INT>("fn add(x, n) { x + n } let x = 40; x.add(2)")?,
         42
     );
 
+    #[cfg(not(feature = "no_object"))]
+    assert_eq!(
+        engine.eval::<INT>("fn add(x, n) { x += n; } let x = 40; x.add(2); x")?,
+        40
+    );
+
     assert_eq!(engine.eval::<INT>("fn mul2(x) { x * 2 } mul2(21)")?, 42);
 
     #[cfg(not(feature = "no_object"))]
@@ -21,5 +32,11 @@ fn test_functions() -> Result<(), Box<EvalAltResult>> {
         42
     );
 
+    #[cfg(not(feature = "no_object"))]
+    assert_eq!(
+        engine.eval::<INT>("fn mul2(x) { x *= 2; } let x = 21; x.mul2(); x")?,
+        21
+    );
+
     Ok(())
 }

tests/get_set.rs

@@ -1,6 +1,6 @@
 #![cfg(not(feature = "no_object"))]
 
-use rhai::{Engine, EvalAltResult, RegisterFn, INT};
+use rhai::{Engine, EvalAltResult, ImmutableString, RegisterFn, INT};
 
 #[test]
 fn test_get_set() -> Result<(), Box<EvalAltResult>> {
@@ -43,7 +43,9 @@ fn test_get_set() -> Result<(), Box<EvalAltResult>> {
     engine.register_fn("new_ts", TestStruct::new);
 
     #[cfg(not(feature = "no_index"))]
-    engine.register_indexer(|value: &mut TestStruct, index: String| value.array[index.len()]);
+    engine.register_indexer(|value: &mut TestStruct, index: ImmutableString| {
+        value.array[index.len()]
+    });
 
     assert_eq!(engine.eval::<INT>("let a = new_ts(); a.x = 500; a.x")?, 500);
     assert_eq!(engine.eval::<INT>("let a = new_ts(); a.x.add(); a.x")?, 42);

tests/maps.rs

@@ -21,6 +21,10 @@ fn test_map_indexing() -> Result<(), Box<EvalAltResult>> {
             )?,
             'o'
         );
+        assert_eq!(
+            engine.eval::<String>(r#"let a = [#{s:"hello"}]; a[0].s[2] = 'X'; a[0].s"#)?,
+            "heXlo"
+        );
     }
 
     assert_eq!(

tests/method_call.rs

@@ -33,7 +33,7 @@ fn test_method_call() -> Result<(), Box<EvalAltResult>> {
 
     assert_eq!(
         engine.eval::<TestStruct>("let x = new_ts(); update(x, 1000); x")?,
-        TestStruct { x: 1 }
+        TestStruct { x: 1001 }
     );
 
     Ok(())

tests/modules.rs

@@ -63,6 +63,9 @@ fn test_module_resolver() -> Result<(), Box<EvalAltResult>> {
 
     let mut module = Module::new();
     module.set_var("answer", 42 as INT);
+    module.set_fn_4("sum".to_string(), |x: INT, y: INT, z: INT, w: INT| {
+        Ok(x + y + z + w)
+    });
 
     resolver.insert("hello".to_string(), module);
 
@@ -74,69 +77,72 @@ fn test_module_resolver() -> Result<(), Box<EvalAltResult>> {
             r#"
                 import "hello" as h1;
                 import "hello" as h2;
-                h2::answer
+                h1::sum(h2::answer, -10, 3, 7)
     "#
         )?,
         42
     );
 
-    engine.set_max_modules(5);
+    #[cfg(not(feature = "unchecked"))]
+    {
+        engine.set_max_modules(5);
 
-    assert!(matches!(
-        *engine
-            .eval::<INT>(
-                r#"
-                    let x = 0;
+        assert!(matches!(
+            *engine
+                .eval::<INT>(
+                    r#"
+                        let sum = 0;
 
-                    for x in range(0, 10) {
-                        import "hello" as h;
-                        x += h::answer;
-                    }
+                        for x in range(0, 10) {
+                            import "hello" as h;
+                            sum += h::answer;
+                        }
 
-                    x
+                        sum
             "#
-            )
-            .expect_err("should error"),
-        EvalAltResult::ErrorTooManyModules(_)
-    ));
+                )
+                .expect_err("should error"),
+            EvalAltResult::ErrorTooManyModules(_)
+        ));
 
-    #[cfg(not(feature = "no_function"))]
-    assert!(matches!(
-        *engine
-            .eval::<INT>(
-                r#"
-                    let x = 0;
+        #[cfg(not(feature = "no_function"))]
+        assert!(matches!(
+            *engine
+                .eval::<INT>(
+                    r#"
+                        let sum = 0;
 
-                    fn foo() {
-                        import "hello" as h;
-                        x += h::answer;
-                    }
+                        fn foo() {
+                            import "hello" as h;
+                            sum += h::answer;
+                        }
 
-                    for x in range(0, 10) {
-                        foo();
-                    }
+                        for x in range(0, 10) {
+                            foo();
+                        }
 
-                    x
+                        sum
             "#
-            )
-            .expect_err("should error"),
-        EvalAltResult::ErrorInFunctionCall(fn_name, _, _) if fn_name == "foo"
-    ));
+                )
+                .expect_err("should error"),
+            EvalAltResult::ErrorInFunctionCall(fn_name, _, _) if fn_name == "foo"
+        ));
 
-    engine.set_max_modules(0);
+        engine.set_max_modules(0);
 
-    #[cfg(not(feature = "no_function"))]
-    engine.eval::<()>(
-        r#"
-            fn foo() {
-                import "hello" as h;
-            }
+        #[cfg(not(feature = "no_function"))]
+        engine.eval::<()>(
+            r#"
+                fn foo() {
+                    import "hello" as h;
+                }
 
-            for x in range(0, 10) {
-                foo();
-            }
+                for x in range(0, 10) {
+                    foo();
+                }
     "#,
-    )?;
+        )?;
+    }
 
     Ok(())
 }

tests/string.rs

@@ -20,21 +20,20 @@ fn test_string() -> Result<(), Box<EvalAltResult>> {
     assert!(engine.eval::<bool>(r#"let y = "hello, world!"; 'w' in y"#)?);
     assert!(!engine.eval::<bool>(r#"let y = "hello, world!"; "hey" in y"#)?);
 
-    #[cfg(not(feature = "no_stdlib"))]
     assert_eq!(engine.eval::<String>(r#""foo" + 123"#)?, "foo123");
 
-    #[cfg(not(feature = "no_stdlib"))]
     #[cfg(not(feature = "no_object"))]
     assert_eq!(engine.eval::<String>("(42).to_string()")?, "42");
 
+    #[cfg(not(feature = "no_object"))]
+    assert_eq!(engine.eval::<char>(r#"let y = "hello"; y[y.len-1]"#)?, 'o');
+
     #[cfg(not(feature = "no_float"))]
-    #[cfg(not(feature = "no_stdlib"))]
     assert_eq!(engine.eval::<String>(r#""foo" + 123.4556"#)?, "foo123.4556");
 
     Ok(())
 }
 
-#[cfg(not(feature = "no_stdlib"))]
 #[cfg(not(feature = "no_object"))]
 #[test]
 fn test_string_substring() -> Result<(), Box<EvalAltResult>> {

tests/time.rs

@@ -1,4 +1,3 @@
-#![cfg(not(feature = "no_stdlib"))]
 #![cfg(not(feature = "no_std"))]
 
 use rhai::{Engine, EvalAltResult, INT};