Support for anonymous functions.

RELEASES.md

@@ -4,12 +4,17 @@ Rhai Release Notes
 Version 0.18.0
 ==============
 
+This version adds:
+
+* Anonymous functions (in closure syntax).  Simplifies creation of ad hoc functions.
+
 New features
 ------------
 
 * `call` can now be called function-call style for function pointers - this is to handle builds with `no_object`.
 * Disallow many keywords as variables, such as `print`, `eval`, `call`, `this` etc.
 * `x.call(f, ...)` allows binding `x` to `this` for the function referenced by the function pointer `f`.
+* Anonymous functions in the syntax of a closure, e.g. `|x, y, z| x + y - z`.
 
 
 Version 0.17.0

doc/src/language/fn-ptr.md

@@ -163,4 +163,59 @@ x == 42;
 Beware that this only works for _method-call_ style.  Normal function-call style cannot bind
 the `this` pointer (for syntactic reasons).
 
-Therefore, obviously, binding the `this` pointer is unsupported under [`no_function`].
+Therefore, obviously, binding the `this` pointer is unsupported under [`no_object`].
+
+
+Anonymous Functions
+-------------------
+
+Sometimes it gets tedious to define separate functions only to dispatch them via single function pointers.
+This scenario is especially common when simulating object-oriented programming ([OOP]).
+
+```rust
+// Define object
+let obj = #{
+    data: 42,
+    increment: Fn("inc_obj"),   // use function pointers to
+    decrement: Fn("dec_obj"),   // refer to method functions
+    print: Fn("print_obj")
+};
+
+// Define method functions one-by-one
+fn inc_obj(x) { this.data += x; }
+fn dec_obj(x) { this.data -= x; }
+fn print_obj() { print(this.data); }
+```
+
+The above can be replaced by using _anonymous functions_ which have the same syntax as Rust's closures
+(but they are **NOT** closures, merely syntactic sugar):
+
+```rust
+let obj = #{
+    data: 42,
+    increment: |x| this.data += x,          // one-liner
+    decrement: |x| this.data -= x,
+    print_obj: || { print(this.data); }     // full function body
+};
+```
+
+The anonymous functions will be expanded into separate functions in the global namespace:
+
+```rust
+let obj = #{
+    data: 42,
+    increment: Fn("anon_fn_1000"),
+    decrement: Fn("anon_fn_1001"),
+    print: Fn("anon_fn_1002")
+};
+
+fn anon_fn_1000(x) { this.data += x; }
+fn anon_fn_1001(x) { this.data -= x; }
+fn anon_fn_1002() { print this.data; }
+```
+
+### WARNING - NOT Closures
+
+Remember: anonymous functions, though having the same syntax as Rust _closures_, are themselves
+**not** closures.  In particular, they do not capture their running environment.  They are more like
+Rust's function pointers.

doc/src/language/object-maps-oop.md

@@ -20,17 +20,21 @@ to the [object map] before the function is called.  There is no way to simulate
 via a normal function-call syntax because all scripted function arguments are passed by value.
 
 ```rust
-fn do_action(x) { print(this.data + x); }   // 'this' binds to the object when called
+fn do_action(x) { this.data += x; }          // 'this' binds to the object when called
 
 let obj = #{
                 data: 40,
                 action: Fn("do_action")      // 'action' holds a function pointer to 'do_action'
            };
 
-obj.action(2);                              // Short-hand syntax: prints 42
+obj.action(2);                               // Calls 'do_action' with `this` bound to 'obj'
 
-// To achieve the above with normal function pointer calls:
+obj.call(obj.action, 2);                     // The above de-sugars to this
-fn do_action(map, x) { print(map.data + x); }
 
-obj.action.call(obj, 2);                    // this call cannot mutate 'obj'
+obj.data == 42;
+
+// To achieve the above with normal function pointer call will fail.
+fn do_action(map, x) { map.data += x; }      // 'map' is a copy
+
+obj.action.call(obj, 2);                     // 'obj' is passed as a copy by value
 ```

doc/src/language/oop.md

@@ -17,24 +17,23 @@ Rhai's [object maps] has [special support for OOP]({{rootUrl}}/language/object-m
 | [Object map] properties holding values                | properties  |
 | [Object map] properties that hold [function pointers] |   methods   |
 
+When a property of an [object map] is called like a method function, and if it happens to hold
+a valid [function pointer] (perhaps defined via an [anonymous function]), then the call will be
+dispatched to the actual function with `this` binding to the [object map] itself.
 
 Examples
 --------
 
 ```rust
 // Define the object
-let obj = #{
+let obj =
+     #{
           data: 0,
-                increment: Fn("add"),       // when called, 'this' binds to 'obj'
+          increment: |x| this.data += x,    // when called, 'this' binds to 'obj'
-                update: Fn("update"),       // when called, 'this' binds to 'obj'
+          update: |x| this.data = x,        // when called, 'this' binds to 'obj'
-                action: Fn("action")        // when called, 'this' binds to 'obj'
+          action: || print(this.data)       // when called, 'this' binds to 'obj'
      };
 
-// Define functions
-fn add(x)       { this.data += x; }         // update using 'this'
-fn update(x)    { this.data = x; }          // update using 'this'
-fn action()     { print(this.data); }       // access properties of 'this'
-
 // Use the object
 obj.increment(1);
 obj.action();                               // prints 1

doc/src/links.md

@@ -78,6 +78,8 @@
 [function pointers]: {{rootUrl}}/language/fn-ptr.md
 [function namespace]: {{rootUrl}}/language/fn-namespaces.md
 [function namespaces]: {{rootUrl}}/language/fn-namespaces.md
+[anonymous function]: {{rootUrl}}/language/fn-ptr.md#anonymous-functions
+[anonymous functions]: {{rootUrl}}/language/fn-ptr.md#anonymous-functions
 
 [`Module`]: {{rootUrl}}/language/modules/index.md
 [module]: {{rootUrl}}/language/modules/index.md

src/any.rs

@@ -18,6 +18,7 @@ use crate::stdlib::{
     boxed::Box,
     collections::HashMap,
     fmt,
+    hash::Hash,
     string::String,
     vec::Vec,
 };

src/engine.rs

@@ -87,6 +87,7 @@ pub const FN_GET: &str = "get$";
 pub const FN_SET: &str = "set$";
 pub const FN_IDX_GET: &str = "index$get$";
 pub const FN_IDX_SET: &str = "index$set$";
+pub const FN_ANONYMOUS: &str = "anon$";
 
 #[cfg(feature = "internals")]
 pub const MARKER_EXPR: &str = "$expr$";
@@ -654,7 +655,7 @@ impl Engine {
         args: &mut FnCallArgs,
         is_ref: bool,
         is_method: bool,
-        def_val: Option<&Dynamic>,
+        def_val: Option<bool>,
         level: usize,
     ) -> Result<(Dynamic, bool), Box<EvalAltResult>> {
         self.inc_operations(state)?;
@@ -815,7 +816,7 @@ impl Engine {
 
         // Return default value (if any)
         if let Some(val) = def_val {
-            return Ok((val.clone(), false));
+            return Ok((val.into(), false));
         }
 
         // Getter function not found?
@@ -976,7 +977,7 @@ impl Engine {
         args: &mut FnCallArgs,
         is_ref: bool,
         is_method: bool,
-        def_val: Option<&Dynamic>,
+        def_val: Option<bool>,
         level: usize,
     ) -> Result<(Dynamic, bool), Box<EvalAltResult>> {
         // Qualifiers (none) + function name + number of arguments + argument `TypeId`'s.
@@ -1081,7 +1082,6 @@ impl Engine {
 
         let is_ref = target.is_ref();
         let is_value = target.is_value();
-        let def_val = def_val.as_ref();
 
         // Get a reference to the mutation target Dynamic
         let obj = target.as_mut();
@@ -1100,7 +1100,7 @@ impl Engine {
 
             // Map it to name(args) in function-call style
             self.exec_fn_call(
-                state, lib, fn_name, *native, hash, args, false, false, def_val, level,
+                state, lib, fn_name, *native, hash, args, false, false, *def_val, level,
             )
         } else if fn_name == KEYWORD_FN_PTR_CALL && idx.len() > 0 && idx[0].is::<FnPtr>() {
             // FnPtr call on object
@@ -1120,7 +1120,7 @@ impl Engine {
 
             // Map it to name(args) in function-call style
             self.exec_fn_call(
-                state, lib, &fn_name, *native, hash, args, is_ref, true, def_val, level,
+                state, lib, &fn_name, *native, hash, args, is_ref, true, *def_val, level,
             )
         } else {
             let redirected: Option<ImmutableString>;
@@ -1146,7 +1146,7 @@ impl Engine {
             let args = arg_values.as_mut();
 
             self.exec_fn_call(
-                state, lib, fn_name, *native, hash, args, is_ref, true, def_val, level,
+                state, lib, fn_name, *native, hash, args, is_ref, true, *def_val, level,
             )
         }
         .map_err(|err| err.new_position(*pos))?;
@@ -1694,13 +1694,12 @@ impl Engine {
             #[cfg(not(feature = "no_index"))]
             Dynamic(Union::Array(mut rhs_value)) => {
                 let op = "==";
-                let def_value = false.into();
                 let mut scope = Scope::new();
 
                 // Call the `==` operator to compare each value
                 for value in rhs_value.iter_mut() {
+                    let def_value = Some(false);
                     let args = &mut [&mut lhs_value.clone(), value];
-                    let def_value = Some(&def_value);
 
                     let hashes = (
                         // Qualifiers (none) + function name + number of arguments + argument `TypeId`'s.
@@ -1782,6 +1781,7 @@ impl Engine {
             Expr::FloatConstant(x) => Ok(x.0.into()),
             Expr::StringConstant(x) => Ok(x.0.to_string().into()),
             Expr::CharConstant(x) => Ok(x.0.into()),
+            Expr::FnPointer(x) => Ok(FnPtr::new_unchecked(x.0.clone()).into()),
             Expr::Variable(x) if (x.0).0 == KEYWORD_THIS => {
                 if let Some(ref val) = this_ptr {
                     Ok((*val).clone())
@@ -1941,7 +1941,6 @@ impl Engine {
             // Normal function call
             Expr::FnCall(x) if x.1.is_none() => {
                 let ((name, native, pos), _, hash, args_expr, def_val) = x.as_ref();
-                let def_val = def_val.as_ref();
 
                 // Handle Fn()
                 if name == KEYWORD_FN_PTR && args_expr.len() == 1 {
@@ -2072,7 +2071,7 @@ impl Engine {
 
                 let args = args.as_mut();
                 self.exec_fn_call(
-                    state, lib, name, *native, hash, args, is_ref, false, def_val, level,
+                    state, lib, name, *native, hash, args, is_ref, false, *def_val, level,
                 )
                 .map(|(v, _)| v)
                 .map_err(|err| err.new_position(*pos))
@@ -2166,7 +2165,7 @@ impl Engine {
                         .map_err(|err| err.new_position(*pos)),
                     Err(err) => match *err {
                         EvalAltResult::ErrorFunctionNotFound(_, _) if def_val.is_some() => {
-                            Ok(def_val.clone().unwrap())
+                            Ok(def_val.unwrap().into())
                         }
                         EvalAltResult::ErrorFunctionNotFound(_, _) => {
                             Err(Box::new(EvalAltResult::ErrorFunctionNotFound(

src/error.rs

@@ -206,6 +206,9 @@ impl fmt::Display for ParseErrorType {
 
             Self::FnMissingParams(s) => write!(f, "Expecting parameters for function '{}'", s),
 
+            Self::FnMissingBody(s) if s.is_empty() => {
+                f.write_str("Expecting body statement block for anonymous function")
+            }
             Self::FnMissingBody(s) => {
                 write!(f, "Expecting body statement block for function '{}'", s)
             }

src/module.rs

@@ -1098,7 +1098,7 @@ impl Module {
 ///
 /// A `StaticVec` is used because most module-level access contains only one level,
 /// and it is wasteful to always allocate a `Vec` with one element.
-#[derive(Clone, Eq, PartialEq, Default)]
+#[derive(Clone, Eq, PartialEq, Default, Hash)]
 pub struct ModuleRef(StaticVec<(String, Position)>, Option<NonZeroUsize>);
 
 impl fmt::Debug for ModuleRef {

src/optimize.rs

@@ -1,9 +1,12 @@
 use crate::any::Dynamic;
 use crate::calc_fn_hash;
-use crate::engine::{Engine, Imports, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_PRINT, KEYWORD_TYPE_OF};
+use crate::engine::{
+    Engine, Imports, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_PRINT, KEYWORD_TYPE_OF,
+};
 use crate::module::Module;
 use crate::parser::{map_dynamic_to_expr, Expr, ReturnType, ScriptFnDef, Stmt, AST};
 use crate::scope::{Entry as ScopeEntry, EntryType as ScopeEntryType, Scope};
+use crate::token::is_valid_identifier;
 use crate::utils::StaticVec;
 
 #[cfg(feature = "internals")]
@@ -528,6 +531,19 @@ fn optimize_expr(expr: Expr, state: &mut State) -> Expr {
             Expr::FnCall(x)
         }
 
+        // Fn("...")
+        Expr::FnCall(x)
+            if x.1.is_none()
+            && (x.0).0 == KEYWORD_FN_PTR
+            && x.3.len() == 1
+            && matches!(x.3[0], Expr::StringConstant(_))
+        => {
+            match &x.3[0] {
+                Expr::StringConstant(s) if is_valid_identifier(s.0.chars()) => Expr::FnPointer(s.clone()),
+                _ => Expr::FnCall(x)
+            }
+        }
+
         // Eagerly call functions
         Expr::FnCall(mut x)
                 if x.1.is_none() // Non-qualified
@@ -571,7 +587,7 @@ fn optimize_expr(expr: Expr, state: &mut State) -> Expr {
                         Some(arg_for_type_of.to_string().into())
                     } else {
                         // Otherwise use the default value, if any
-                        def_value.clone()
+                        def_value.map(|v| v.into())
                     }
                 })
                 .and_then(|result| map_dynamic_to_expr(result, *pos))

src/parser.rs

@@ -2,7 +2,7 @@
 
 use crate::any::{Dynamic, Union};
 use crate::calc_fn_hash;
-use crate::engine::{make_getter, make_setter, Engine, KEYWORD_THIS};
+use crate::engine::{make_getter, make_setter, Engine, FN_ANONYMOUS, KEYWORD_THIS};
 use crate::error::{LexError, ParseError, ParseErrorType};
 use crate::module::{Module, ModuleRef};
 use crate::optimize::{optimize_into_ast, OptimizationLevel};
@@ -35,6 +35,12 @@ use crate::stdlib::{
     vec::Vec,
 };
 
+#[cfg(not(feature = "no_std"))]
+use crate::stdlib::collections::hash_map::DefaultHasher;
+
+#[cfg(feature = "no_std")]
+use ahash::AHasher;
+
 /// The system integer type.
 ///
 /// If the `only_i32` feature is enabled, this will be `i32` instead.
@@ -598,21 +604,34 @@ impl Hash for CustomExpr {
     }
 }
 
+#[cfg(not(feature = "no_float"))]
+#[derive(Debug, PartialEq, PartialOrd, Clone)]
+pub struct FloatWrapper(pub FLOAT, pub Position);
+
+impl Hash for FloatWrapper {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        state.write(&self.0.to_le_bytes());
+        self.1.hash(state);
+    }
+}
+
 /// An expression.
 ///
 /// Each variant is at most one pointer in size (for speed),
 /// with everything being allocated together in one single tuple.
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Hash)]
 pub enum Expr {
     /// Integer constant.
     IntegerConstant(Box<(INT, Position)>),
     /// Floating-point constant.
     #[cfg(not(feature = "no_float"))]
-    FloatConstant(Box<(FLOAT, Position)>),
+    FloatConstant(Box<FloatWrapper>),
     /// Character constant.
     CharConstant(Box<(char, Position)>),
     /// String constant.
     StringConstant(Box<(ImmutableString, Position)>),
+    /// FnPtr constant.
+    FnPointer(Box<(ImmutableString, Position)>),
     /// Variable access - ((variable name, position), optional modules, hash, optional index)
     Variable(
         Box<(
@@ -637,7 +656,7 @@ pub enum Expr {
             Option<Box<ModuleRef>>,
             u64,
             StaticVec<Expr>,
-            Option<Dynamic>,
+            Option<bool>,
         )>,
     ),
     /// expr op= expr
@@ -673,18 +692,6 @@ impl Default for Expr {
     }
 }
 
-impl Hash for Expr {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        match self {
-            Self::FloatConstant(x) => {
-                state.write(&x.0.to_le_bytes());
-                x.1.hash(state);
-            }
-            _ => self.hash(state),
-        }
-    }
-}
-
 impl Expr {
     /// Get the `Dynamic` value of a constant expression.
     ///
@@ -758,6 +765,7 @@ impl Expr {
             Self::IntegerConstant(x) => x.1,
             Self::CharConstant(x) => x.1,
             Self::StringConstant(x) => x.1,
+            Self::FnPointer(x) => x.1,
             Self::Array(x) => x.1,
             Self::Map(x) => x.1,
             Self::Property(x) => x.1,
@@ -791,6 +799,7 @@ impl Expr {
             Self::IntegerConstant(x) => x.1 = new_pos,
             Self::CharConstant(x) => x.1 = new_pos,
             Self::StringConstant(x) => x.1 = new_pos,
+            Self::FnPointer(x) => x.1 = new_pos,
             Self::Array(x) => x.1 = new_pos,
             Self::Map(x) => x.1 = new_pos,
             Self::Variable(x) => (x.0).1 = new_pos,
@@ -847,6 +856,7 @@ impl Expr {
             Self::IntegerConstant(_)
             | Self::CharConstant(_)
             | Self::StringConstant(_)
+            | Self::FnPointer(_)
             | Self::True(_)
             | Self::False(_)
             | Self::Unit(_) => true,
@@ -878,6 +888,7 @@ impl Expr {
 
             Self::IntegerConstant(_)
             | Self::CharConstant(_)
+            | Self::FnPointer(_)
             | Self::In(_)
             | Self::And(_)
             | Self::Or(_)
@@ -1476,7 +1487,7 @@ fn parse_primary(
     let mut root_expr = match token {
         Token::IntegerConstant(x) => Expr::IntegerConstant(Box::new((x, settings.pos))),
         #[cfg(not(feature = "no_float"))]
-        Token::FloatConstant(x) => Expr::FloatConstant(Box::new((x, settings.pos))),
+        Token::FloatConstant(x) => Expr::FloatConstant(Box::new(FloatWrapper(x, settings.pos))),
         Token::CharConstant(c) => Expr::CharConstant(Box::new((c, settings.pos))),
         Token::StringConstant(s) => Expr::StringConstant(Box::new((s.into(), settings.pos))),
         Token::Identifier(s) => {
@@ -1616,7 +1627,10 @@ fn parse_unary(
                         .map(|i| Expr::IntegerConstant(Box::new((i, pos))))
                         .or_else(|| {
                             #[cfg(not(feature = "no_float"))]
-                            return Some(Expr::FloatConstant(Box::new((-(x.0 as FLOAT), pos))));
+                            return Some(Expr::FloatConstant(Box::new(FloatWrapper(
+                                -(x.0 as FLOAT),
+                                pos,
+                            ))));
                             #[cfg(feature = "no_float")]
                             return None;
                         })
@@ -1625,7 +1639,9 @@ fn parse_unary(
 
                 // Negative float
                 #[cfg(not(feature = "no_float"))]
-                Expr::FloatConstant(x) => Ok(Expr::FloatConstant(Box::new((-x.0, x.1)))),
+                Expr::FloatConstant(x) => {
+                    Ok(Expr::FloatConstant(Box::new(FloatWrapper(-x.0, x.1))))
+                }
 
                 // Call negative function
                 expr => {
@@ -1664,9 +1680,38 @@ fn parse_unary(
                 None,
                 hash,
                 args,
-                Some(false.into()), // NOT operator, when operating on invalid operand, defaults to false
+                Some(false), // NOT operator, when operating on invalid operand, defaults to false
             ))))
         }
+        // | ...
+        #[cfg(not(feature = "no_function"))]
+        Token::Pipe | Token::Or => {
+            let mut state = ParseState::new(
+                state.engine,
+                state.max_function_expr_depth,
+                state.max_function_expr_depth,
+            );
+
+            let settings = ParseSettings {
+                allow_if_expr: true,
+                allow_stmt_expr: true,
+                allow_anonymous_fn: true,
+                is_global: false,
+                is_function_scope: true,
+                is_breakable: false,
+                level: 0,
+                pos: *token_pos,
+            };
+
+            let (expr, func) = parse_anon_fn(input, &mut state, lib, settings)?;
+
+            // Qualifiers (none) + function name + number of arguments.
+            let hash = calc_fn_hash(empty(), &func.name, func.params.len(), empty());
+
+            lib.insert(hash, func);
+
+            Ok(expr)
+        }
         // <EOF>
         Token::EOF => Err(PERR::UnexpectedEOF.into_err(settings.pos)),
         // All other tokens
@@ -2018,7 +2063,7 @@ fn parse_binary_op(
         settings.pos = pos;
         settings.ensure_level_within_max_limit(state.max_expr_depth)?;
 
-        let cmp_def = Some(false.into());
+        let cmp_def = Some(false);
         let op = op_token.syntax();
         let hash = calc_fn_hash(empty(), &op, 2, empty());
         let op = (op, true, pos);
@@ -2041,7 +2086,7 @@ fn parse_binary_op(
             | Token::XOr => Expr::FnCall(Box::new((op, None, hash, args, None))),
 
             // '!=' defaults to true when passed invalid operands
-            Token::NotEqualsTo => Expr::FnCall(Box::new((op, None, hash, args, Some(true.into())))),
+            Token::NotEqualsTo => Expr::FnCall(Box::new((op, None, hash, args, Some(true)))),
 
             // Comparison operators default to false when passed invalid operands
             Token::EqualsTo
@@ -2762,32 +2807,28 @@ fn parse_fn(
     let mut params = Vec::new();
 
     if !match_token(input, Token::RightParen)? {
-        let end_err = format!("to close the parameters list of function '{}'", name);
         let sep_err = format!("to separate the parameters of function '{}'", name);
 
         loop {
-            match input.peek().unwrap() {
+            match input.next().unwrap() {
-                (Token::RightParen, _) => (),
+                (Token::RightParen, _) => break,
-                _ => match input.next().unwrap() {
                 (Token::Identifier(s), pos) => {
                     state.stack.push((s.clone(), ScopeEntryType::Normal));
                     params.push((s, pos))
                 }
                 (Token::LexError(err), pos) => return Err(err.into_err(pos)),
                 (_, pos) => {
-                        return Err(
+                    return Err(PERR::MissingToken(
-                            PERR::MissingToken(Token::RightParen.into(), end_err).into_err(pos)
+                        Token::RightParen.into(),
+                        format!("to close the parameters list of function '{}'", name),
                     )
+                    .into_err(pos))
                 }
-                },
             }
 
             match input.next().unwrap() {
                 (Token::RightParen, _) => break,
                 (Token::Comma, _) => (),
-                (Token::Identifier(_), pos) => {
-                    return Err(PERR::MissingToken(Token::Comma.into(), sep_err).into_err(pos))
-                }
                 (Token::LexError(err), pos) => return Err(err.into_err(pos)),
                 (_, pos) => {
                     return Err(PERR::MissingToken(Token::Comma.into(), sep_err).into_err(pos))
@@ -2831,6 +2872,101 @@ fn parse_fn(
     })
 }
 
+/// Parse an anonymous function definition.
+#[cfg(not(feature = "no_function"))]
+fn parse_anon_fn(
+    input: &mut TokenStream,
+    state: &mut ParseState,
+    lib: &mut FunctionsLib,
+    mut settings: ParseSettings,
+) -> Result<(Expr, ScriptFnDef), ParseError> {
+    settings.ensure_level_within_max_limit(state.max_expr_depth)?;
+
+    let mut params = Vec::new();
+
+    if input.next().unwrap().0 != Token::Or {
+        if !match_token(input, Token::Pipe)? {
+            loop {
+                match input.next().unwrap() {
+                    (Token::Pipe, _) => break,
+                    (Token::Identifier(s), pos) => {
+                        state.stack.push((s.clone(), ScopeEntryType::Normal));
+                        params.push((s, pos))
+                    }
+                    (Token::LexError(err), pos) => return Err(err.into_err(pos)),
+                    (_, pos) => {
+                        return Err(PERR::MissingToken(
+                            Token::Pipe.into(),
+                            "to close the parameters list of anonymous function".into(),
+                        )
+                        .into_err(pos))
+                    }
+                }
+
+                match input.next().unwrap() {
+                    (Token::Pipe, _) => break,
+                    (Token::Comma, _) => (),
+                    (Token::LexError(err), pos) => return Err(err.into_err(pos)),
+                    (_, pos) => {
+                        return Err(PERR::MissingToken(
+                            Token::Comma.into(),
+                            "to separate the parameters of anonymous function".into(),
+                        )
+                        .into_err(pos))
+                    }
+                }
+            }
+        }
+    }
+
+    // Check for duplicating parameters
+    params
+        .iter()
+        .enumerate()
+        .try_for_each(|(i, (p1, _))| {
+            params
+                .iter()
+                .skip(i + 1)
+                .find(|(p2, _)| p2 == p1)
+                .map_or_else(|| Ok(()), |(p2, pos)| Err((p2, *pos)))
+        })
+        .map_err(|(p, pos)| PERR::FnDuplicatedParam("".to_string(), p.to_string()).into_err(pos))?;
+
+    // Parse function body
+    settings.is_breakable = false;
+    let pos = input.peek().unwrap().1;
+    let body = parse_stmt(input, state, lib, settings.level_up())
+        .map(|stmt| stmt.unwrap_or_else(|| Stmt::Noop(pos)))?;
+
+    let params: StaticVec<_> = params.into_iter().map(|(p, _)| p).collect();
+
+    // Calculate hash
+    #[cfg(feature = "no_std")]
+    let mut s: AHasher = Default::default();
+    #[cfg(not(feature = "no_std"))]
+    let mut s = DefaultHasher::new();
+
+    s.write_usize(params.len());
+    params.iter().for_each(|a| a.hash(&mut s));
+    body.hash(&mut s);
+    let hash = s.finish();
+
+    // Create unique function name
+    let fn_name = format!("{}{}", FN_ANONYMOUS, hash);
+
+    let script = ScriptFnDef {
+        name: fn_name.clone(),
+        access: FnAccess::Public,
+        params,
+        body,
+        pos: settings.pos,
+    };
+
+    let expr = Expr::FnPointer(Box::new((fn_name.into(), settings.pos)));
+
+    Ok((expr, script))
+}
+
 impl Engine {
     pub(crate) fn parse_global_expr(
         &self,
@@ -2951,7 +3087,7 @@ impl Engine {
 pub fn map_dynamic_to_expr(value: Dynamic, pos: Position) -> Option<Expr> {
     match value.0 {
         #[cfg(not(feature = "no_float"))]
-        Union::Float(value) => Some(Expr::FloatConstant(Box::new((value, pos)))),
+        Union::Float(value) => Some(Expr::FloatConstant(Box::new(FloatWrapper(value, pos)))),
 
         Union::Unit(_) => Some(Expr::Unit(pos)),
         Union::Int(value) => Some(Expr::IntegerConstant(Box::new((value, pos)))),