diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7627368d..eee62da7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ Buf fixes
 
 * `is_shared` is a reserved keyword and is now handled properly (e.g. it cannot be the target of a function pointer).
 * Re-optimizing an AST via `optimize_ast` with constants now works correctly for closures. Previously the hidden `Share` nodes are not removed and causes variable-not-found errors during runtime if the constants are not available in the scope.
+* Expressions such as `(v[0].func()).prop` now parse correctly.
 
 New features
 ------------
@@ -18,6 +19,11 @@ New features
 * It is now possible to require a specific _type_ to the `this` pointer for a particular script-defined function so that it is called only when the `this` pointer contains the specified type.
 * `is_def_fn` is extended to support checking for typed methods, with syntax `is_def_fn(this_type, fn_name, arity)`
 
+Enhancements
+------------
+
+* `Engine::is_symbol_disabled` is added to test whether a particular keyword/symbol is disabled.
+
 
 Version 1.13.0
 ==============
diff --git a/src/README.md b/src/README.md
index fc1d7bbf..e02fd0b2 100644
--- a/src/README.md
+++ b/src/README.md
@@ -11,21 +11,23 @@ Root Sources
 | `tokenizer.rs` | Script tokenizer/lexer                                                          |
 | `parser.rs`    | Script parser                                                                   |
 | `optimizer.rs` | Script optimizer                                                                |
+| `defer.rs`     | Utilities for deferred clean-up of resources                                    |
 | `reify.rs`     | Utilities for making generic types concrete                                     |
-| `tests.rs`     | Unit tests (not integration tests, which are in the `rhai/tests` sub-directory) |
+| `tests.rs`     | Unit tests (not integration tests, which are in the main `tests` sub-directory) |
 
 
 Sub-Directories
 ---------------
 
-| Sub-directory | Description                                           |
-| ------------- | ----------------------------------------------------- |
-| `types`       | Common data types (e.g. `Dynamic`, errors)            |
-| `api`         | Public API for the scripting engine                   |
-| `ast`         | AST definition                                        |
-| `module`      | Support for modules                                   |
-| `packages`    | Pre-defined packages                                  |
-| `func`        | Support for function calls                            |
-| `eval`        | Evaluation engine                                     |
-| `serde`       | Support for [`serde`](https://crates.io/crates/serde) |
-| `bin`         | Pre-built CLI binaries (e.g. `rhai-run`, `rhai-repl`) |
+| Sub-directory | Description                                                        |
+| ------------- | ------------------------------------------------------------------ |
+| `config`      | Configuration                                                      |
+| `types`       | Common data types (e.g. `Dynamic`, errors)                         |
+| `api`         | Public API for the scripting engine                                |
+| `ast`         | AST definition                                                     |
+| `module`      | Support for modules                                                |
+| `packages`    | Pre-defined packages                                               |
+| `func`        | Registering and calling functions (native Rust and script-defined) |
+| `eval`        | AST evaluation                                                     |
+| `serde`       | Support for [`serde`](https://crates.io/crates/serde) and metadata |
+| `bin`         | Pre-built CLI binaries                                             |
diff --git a/src/api/custom_syntax.rs b/src/api/custom_syntax.rs
index e5dfb56c..762b5dcc 100644
--- a/src/api/custom_syntax.rs
+++ b/src/api/custom_syntax.rs
@@ -259,15 +259,9 @@ impl Engine {
                 // Keyword/symbol not in first position
                 _ if !segments.is_empty() && token.is_some() => {
                     // Make it a custom keyword/symbol if it is disabled or reserved
-                    if (self
-                        .disabled_symbols
-                        .as_ref()
-                        .map_or(false, |m| m.contains(s))
+                    if (self.is_symbol_disabled(s)
                         || token.as_ref().map_or(false, Token::is_reserved))
-                        && !self
-                            .custom_keywords
-                            .as_ref()
-                            .map_or(false, |m| m.contains_key(s))
+                        && !self.is_custom_keyword(s)
                     {
                         self.custom_keywords
                             .get_or_insert_with(Default::default)
@@ -279,10 +273,7 @@ impl Engine {
                 // Standard keyword in first position but not disabled
                 _ if segments.is_empty()
                     && token.as_ref().map_or(false, Token::is_standard_keyword)
-                    && !self
-                        .disabled_symbols
-                        .as_ref()
-                        .map_or(false, |m| m.contains(s)) =>
+                    && !self.is_symbol_disabled(s) =>
                 {
                     return Err(LexError::ImproperSymbol(
                         s.to_string(),
@@ -299,15 +290,9 @@ impl Engine {
                     && (is_valid_identifier(s) || is_reserved_keyword_or_symbol(s).0) =>
                 {
                     // Make it a custom keyword/symbol if it is disabled or reserved
-                    if self
-                        .disabled_symbols
-                        .as_ref()
-                        .map_or(false, |m| m.contains(s))
+                    if self.is_symbol_disabled(s)
                         || (token.as_ref().map_or(false, Token::is_reserved)
-                            && !self
-                                .custom_keywords
-                                .as_ref()
-                                .map_or(false, |m| m.contains_key(s)))
+                            && !self.is_custom_keyword(s))
                     {
                         self.custom_keywords
                             .get_or_insert_with(Default::default)
diff --git a/src/api/definitions/mod.rs b/src/api/definitions/mod.rs
index 69224b27..f4fae1d6 100644
--- a/src/api/definitions/mod.rs
+++ b/src/api/definitions/mod.rs
@@ -457,12 +457,7 @@ impl Module {
                     !f.metadata.name.contains('$') && !is_valid_function_name(&f.metadata.name);
 
                 #[cfg(not(feature = "no_custom_syntax"))]
-                let operator = operator
-                    || def
-                        .engine
-                        .custom_keywords
-                        .as_ref()
-                        .map_or(false, |m| m.contains_key(f.metadata.name.as_str()));
+                let operator = operator || def.engine.is_custom_keyword(f.metadata.name.as_str());
 
                 f.write_definition(writer, def, operator)?;
             }
diff --git a/src/api/mod.rs b/src/api/mod.rs
index 21238f5a..bc6fa1a6 100644
--- a/src/api/mod.rs
+++ b/src/api/mod.rs
@@ -109,7 +109,7 @@ impl Engine {
     /// # Ok(())
     /// # }
     /// ```
-    #[inline(always)]
+    #[inline]
     pub fn disable_symbol(&mut self, symbol: impl Into<Identifier>) -> &mut Self {
         self.disabled_symbols
             .get_or_insert_with(Default::default)
@@ -117,6 +117,26 @@ impl Engine {
         self
     }
 
+    /// Is a particular keyword or operator disabled?
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use rhai::Engine;
+    ///
+    /// let mut engine = Engine::new();
+    ///
+    /// engine.disable_symbol("if");    // disable the 'if' keyword
+    ///
+    /// assert!(engine.is_symbol_disabled("if"));
+    /// ```
+    #[inline]
+    pub fn is_symbol_disabled(&self, symbol: &str) -> bool {
+        self.disabled_symbols
+            .as_ref()
+            .map_or(false, |m| m.contains(symbol))
+    }
+
     /// Register a custom operator with a precedence into the language.
     ///
     /// Not available under `no_custom_syntax`.
@@ -168,32 +188,21 @@ impl Engine {
             Some(Token::Custom(..)) => (),
             // Active standard keywords cannot be made custom
             // Disabled keywords are OK
-            Some(token) if token.is_standard_keyword() => {
-                if !self
-                    .disabled_symbols
-                    .as_ref()
-                    .map_or(false, |m| m.contains(token.literal_syntax()))
-                {
-                    return Err(format!("'{keyword}' is a reserved keyword"));
-                }
-            }
-            // Active standard symbols cannot be made custom
-            Some(token) if token.is_standard_symbol() => {
-                if !self
-                    .disabled_symbols
-                    .as_ref()
-                    .map_or(false, |m| m.contains(token.literal_syntax()))
-                {
-                    return Err(format!("'{keyword}' is a reserved operator"));
-                }
+            Some(token)
+                if token.is_standard_keyword()
+                    && !self.is_symbol_disabled(token.literal_syntax()) =>
+            {
+                return Err(format!("'{keyword}' is a reserved keyword"))
             }
             // Active standard symbols cannot be made custom
             Some(token)
-                if !self
-                    .disabled_symbols
-                    .as_ref()
-                    .map_or(false, |m| m.contains(token.literal_syntax())) =>
+                if token.is_standard_symbol()
+                    && !self.is_symbol_disabled(token.literal_syntax()) =>
             {
+                return Err(format!("'{keyword}' is a reserved operator"))
+            }
+            // Active standard symbols cannot be made custom
+            Some(token) if !self.is_symbol_disabled(token.literal_syntax()) => {
                 return Err(format!("'{keyword}' is a reserved symbol"))
             }
             // Disabled symbols are OK
@@ -207,6 +216,16 @@ impl Engine {
 
         Ok(self)
     }
+    /// Is a keyword registered as a custom keyword?
+    ///
+    /// Not available under `no_custom_syntax`.
+    #[cfg(not(feature = "no_custom_syntax"))]
+    #[inline]
+    pub(crate) fn is_custom_keyword(&self, keyword: &str) -> bool {
+        self.custom_keywords
+            .as_ref()
+            .map_or(false, |m| m.contains_key(keyword))
+    }
 
     /// Get the default value of the custom state for each evaluation run.
     #[inline(always)]
diff --git a/src/api/register.rs b/src/api/register.rs
index 8f4d4833..285f959a 100644
--- a/src/api/register.rs
+++ b/src/api/register.rs
@@ -90,15 +90,15 @@ impl Engine {
         let param_type_names: Option<&[&str]> = None;
 
         let fn_name = name.as_ref();
-        let no_const = false;
+        let is_pure = true;
 
         #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
-        let no_const = no_const || (F::num_params() == 3 && fn_name == crate::engine::FN_IDX_SET);
+        let is_pure = is_pure && (F::num_params() != 3 || fn_name != crate::engine::FN_IDX_SET);
         #[cfg(not(feature = "no_object"))]
-        let no_const =
-            no_const || (F::num_params() == 2 && fn_name.starts_with(crate::engine::FN_SET));
+        let is_pure =
+            is_pure && (F::num_params() != 2 || !fn_name.starts_with(crate::engine::FN_SET));
 
-        let func = func.into_callable_function(fn_name.into(), no_const);
+        let func = func.into_callable_function(fn_name.into(), is_pure);
 
         self.global_namespace_mut().set_fn(
             name,
diff --git a/src/ast/stmt.rs b/src/ast/stmt.rs
index 65634092..79db87b2 100644
--- a/src/ast/stmt.rs
+++ b/src/ast/stmt.rs
@@ -721,7 +721,7 @@ pub enum Stmt {
     /// This variant does not map to any language structure.  It is currently only used only to
     /// convert normal variables into shared variables when they are _captured_ by a closure.
     #[cfg(not(feature = "no_closure"))]
-    Share(Box<crate::FnArgsVec<(crate::ImmutableString, Option<NonZeroUsize>, Position)>>),
+    Share(Box<crate::FnArgsVec<(crate::ast::Ident, Option<NonZeroUsize>)>>),
 }
 
 impl Default for Stmt {
@@ -816,7 +816,7 @@ impl Stmt {
             Self::Export(.., pos) => *pos,
 
             #[cfg(not(feature = "no_closure"))]
-            Self::Share(x) => x[0].2,
+            Self::Share(x) => x[0].0.pos,
         }
     }
     /// Override the [position][Position] of this statement.
@@ -848,7 +848,7 @@ impl Stmt {
             Self::Export(.., pos) => *pos = new_pos,
 
             #[cfg(not(feature = "no_closure"))]
-            Self::Share(x) => x.iter_mut().for_each(|(_, _, pos)| *pos = new_pos),
+            Self::Share(x) => x.iter_mut().for_each(|(x, _)| x.pos = new_pos),
         }
 
         self
diff --git a/src/eval/stmt.rs b/src/eval/stmt.rs
index 5d090b76..9c88f1cf 100644
--- a/src/eval/stmt.rs
+++ b/src/eval/stmt.rs
@@ -927,19 +927,19 @@ impl Engine {
             // Share statement
             #[cfg(not(feature = "no_closure"))]
             Stmt::Share(x) => {
-                for (name, index, pos) in &**x {
-                    if let Some(index) = index
+                for (var, index) in &**x {
+                    let index = index
                         .map(|n| scope.len() - n.get())
-                        .or_else(|| scope.search(name))
-                    {
-                        let val = scope.get_mut_by_index(index);
+                        .or_else(|| scope.search(&var.name))
+                        .ok_or_else(|| {
+                            Box::new(ERR::ErrorVariableNotFound(var.name.to_string(), var.pos))
+                        })?;
 
-                        if !val.is_shared() {
-                            // Replace the variable with a shared value.
-                            *val = std::mem::take(val).into_shared();
-                        }
-                    } else {
-                        return Err(ERR::ErrorVariableNotFound(name.to_string(), *pos).into());
+                    let val = scope.get_mut_by_index(index);
+
+                    if !val.is_shared() {
+                        // Replace the variable with a shared value.
+                        *val = std::mem::take(val).into_shared();
                     }
                 }
 
diff --git a/src/func/call.rs b/src/func/call.rs
index dac38df3..2cd36208 100644
--- a/src/func/call.rs
+++ b/src/func/call.rs
@@ -276,6 +276,7 @@ impl Engine {
                                             func: CallableFunction::Method {
                                                 func: Shared::new(f),
                                                 has_context,
+                                                is_pure: false,
                                             },
                                             source: None,
                                         })
@@ -285,6 +286,7 @@ impl Engine {
                                         func: CallableFunction::Method {
                                             func: Shared::new(f),
                                             has_context,
+                                            is_pure: true,
                                         },
                                         source: None,
                                     }),
@@ -372,8 +374,8 @@ impl Engine {
 
             let backup = &mut ArgBackup::new();
 
-            // Calling pure function but the first argument is a reference?
-            let swap = is_ref_mut && func.is_pure() && !args.is_empty();
+            // Calling non-method function but the first argument is a reference?
+            let swap = is_ref_mut && !func.is_method() && !args.is_empty();
 
             if swap {
                 // Clone the first argument
@@ -400,12 +402,11 @@ impl Engine {
                 .has_context()
                 .then(|| (self, name, src, &*global, pos).into());
 
-            let mut _result = if let Some(f) = func.get_plugin_fn() {
-                if !f.is_pure() && !args.is_empty() && args[0].is_read_only() {
-                    Err(ERR::ErrorNonPureMethodCallOnConstant(name.to_string(), pos).into())
-                } else {
-                    f.call(context, args)
-                }
+            let mut _result = if !func.is_pure() && !args.is_empty() && args[0].is_read_only() {
+                // If function is not pure, there must be at least one argument
+                Err(ERR::ErrorNonPureMethodCallOnConstant(name.to_string(), pos).into())
+            } else if let Some(f) = func.get_plugin_fn() {
+                f.call(context, args)
             } else if let Some(f) = func.get_native_fn() {
                 f(context, args)
             } else {
@@ -603,8 +604,11 @@ impl Engine {
             };
 
             if error {
-                let sig = self.gen_fn_call_signature(fn_name, args);
-                return Err(ERR::ErrorFunctionNotFound(sig, pos).into());
+                return Err(ERR::ErrorFunctionNotFound(
+                    self.gen_fn_call_signature(fn_name, args),
+                    pos,
+                )
+                .into());
             }
         }
 
@@ -814,12 +818,16 @@ impl Engine {
             // Handle obj.call(fn_ptr, ...)
             KEYWORD_FN_PTR_CALL => {
                 if call_args.is_empty() {
-                    let typ = self.map_type_name(target.type_name());
-                    return Err(self.make_type_mismatch_err::<FnPtr>(typ, fn_call_pos));
+                    return Err(self.make_type_mismatch_err::<FnPtr>(
+                        self.map_type_name(target.type_name()),
+                        fn_call_pos,
+                    ));
                 }
                 if !call_args[0].is_fnptr() {
-                    let typ = self.map_type_name(call_args[0].type_name());
-                    return Err(self.make_type_mismatch_err::<FnPtr>(typ, first_arg_pos));
+                    return Err(self.make_type_mismatch_err::<FnPtr>(
+                        self.map_type_name(call_args[0].type_name()),
+                        first_arg_pos,
+                    ));
                 }
 
                 // FnPtr call on object
@@ -903,8 +911,10 @@ impl Engine {
             }
             KEYWORD_FN_PTR_CURRY => {
                 if !target.is_fnptr() {
-                    let typ = self.map_type_name(target.type_name());
-                    return Err(self.make_type_mismatch_err::<FnPtr>(typ, fn_call_pos));
+                    return Err(self.make_type_mismatch_err::<FnPtr>(
+                        self.map_type_name(target.type_name()),
+                        fn_call_pos,
+                    ));
                 }
 
                 let mut fn_ptr = target.read_lock::<FnPtr>().expect("`FnPtr`").clone();
@@ -1035,8 +1045,10 @@ impl Engine {
                     self.get_arg_value(global, caches, scope, this_ptr.as_deref_mut(), arg)?;
 
                 if !arg_value.is_fnptr() {
-                    let typ = self.map_type_name(arg_value.type_name());
-                    return Err(self.make_type_mismatch_err::<FnPtr>(typ, arg_pos));
+                    return Err(self.make_type_mismatch_err::<FnPtr>(
+                        self.map_type_name(arg_value.type_name()),
+                        arg_pos,
+                    ));
                 }
 
                 let fn_ptr = arg_value.cast::<FnPtr>();
@@ -1121,8 +1133,10 @@ impl Engine {
                     self.get_arg_value(global, caches, scope, this_ptr.as_deref_mut(), first)?;
 
                 if !arg_value.is_fnptr() {
-                    let typ = self.map_type_name(arg_value.type_name());
-                    return Err(self.make_type_mismatch_err::<FnPtr>(typ, arg_pos));
+                    return Err(self.make_type_mismatch_err::<FnPtr>(
+                        self.map_type_name(arg_value.type_name()),
+                        arg_pos,
+                    ));
                 }
 
                 let mut fn_ptr = arg_value.cast::<FnPtr>();
@@ -1493,17 +1507,18 @@ impl Engine {
                 self.call_script_fn(global, caches, scope, None, environ, f, args, true, pos)
             }
 
+            Some(f) if !f.is_pure() && args[0].is_read_only() => {
+                // If function is not pure, there must be at least one argument
+                Err(ERR::ErrorNonPureMethodCallOnConstant(fn_name.to_string(), pos).into())
+            }
+
             Some(f) if f.is_plugin_fn() => {
                 let f = f.get_plugin_fn().expect("plugin function");
                 let context = f
                     .has_context()
                     .then(|| (self, fn_name, module.id(), &*global, pos).into());
-                if !f.is_pure() && !args.is_empty() && args[0].is_read_only() {
-                    Err(ERR::ErrorNonPureMethodCallOnConstant(fn_name.to_string(), pos).into())
-                } else {
-                    f.call(context, args)
-                        .and_then(|r| self.check_data_size(r, pos))
-                }
+                f.call(context, args)
+                    .and_then(|r| self.check_data_size(r, pos))
             }
 
             Some(f) if f.is_native() => {
diff --git a/src/func/callable_function.rs b/src/func/callable_function.rs
index 21a7ae4d..3b66d9a1 100644
--- a/src/func/callable_function.rs
+++ b/src/func/callable_function.rs
@@ -39,6 +39,8 @@ pub enum CallableFunction {
         func: Shared<FnAny>,
         /// Does the function take a [`NativeCallContext`][crate::NativeCallContext] parameter?
         has_context: bool,
+        /// This is a dummy field and is not used.
+        is_pure: bool,
     },
     /// A native Rust object method with the first argument passed by reference,
     /// and the rest passed by value.
@@ -47,6 +49,8 @@ pub enum CallableFunction {
         func: Shared<FnAny>,
         /// Does the function take a [`NativeCallContext`][crate::NativeCallContext] parameter?
         has_context: bool,
+        /// Allow operating on constants?
+        is_pure: bool,
     },
     /// An iterator function.
     Iterator {
@@ -105,9 +109,10 @@ impl CallableFunction {
     pub fn is_pure(&self) -> bool {
         match self {
             Self::Pure { .. } => true,
-            Self::Method { .. } | Self::Iterator { .. } => false,
+            Self::Method { is_pure, .. } => *is_pure,
+            Self::Iterator { .. } => true,
 
-            Self::Plugin { func, .. } => !func.is_method_call(),
+            Self::Plugin { func, .. } => func.is_pure(),
 
             #[cfg(not(feature = "no_function"))]
             Self::Script { .. } => false,
diff --git a/src/func/register.rs b/src/func/register.rs
index de5d835c..ea9ef6d5 100644
--- a/src/func/register.rs
+++ b/src/func/register.rs
@@ -84,7 +84,7 @@ pub trait RegisterNativeFunction<
 {
     /// Convert this function into a [`CallableFunction`].
     #[must_use]
-    fn into_callable_function(self, name: Identifier, no_const: bool) -> CallableFunction;
+    fn into_callable_function(self, name: Identifier, is_pure: bool) -> CallableFunction;
     /// Get the type ID's of this function's parameters.
     #[must_use]
     fn param_types() -> [TypeId; N];
@@ -127,19 +127,6 @@ pub trait RegisterNativeFunction<
     }
 }
 
-macro_rules! check_constant {
-    ($abi:ident, $n:expr, $fn_name:ident, $no_const:ident, $args:ident) => {
-        #[cfg(any(not(feature = "no_object"), not(feature = "no_index")))]
-        if stringify!($abi) == "Method" && $no_const && $args[0].is_read_only() {
-            return Err(crate::ERR::ErrorNonPureMethodCallOnConstant(
-                $fn_name.to_string(),
-                crate::Position::NONE,
-            )
-            .into());
-        }
-    };
-}
-
 macro_rules! def_register {
     () => {
         def_register!(imp Pure : 0;);
@@ -160,11 +147,9 @@ macro_rules! def_register {
         > RegisterNativeFunction<($($mark,)*), $n, false, RET, false> for FN {
             #[inline(always)] fn param_types() -> [TypeId;$n] { [$(TypeId::of::<$par>()),*] }
             #[cfg(feature = "metadata")] #[inline(always)] fn param_names() -> [&'static str;$n] { [$(type_name::<$param>()),*] }
-            #[inline(always)] fn into_callable_function(self, fn_name: Identifier, no_const: bool) -> CallableFunction {
+            #[inline(always)] fn into_callable_function(self, fn_name: Identifier, is_pure: bool) -> CallableFunction {
                 CallableFunction::$abi { func: Shared::new(move |_, args: &mut FnCallArgs| {
                     // The arguments are assumed to be of the correct number and types!
-                    check_constant!($abi, $n, fn_name, no_const, args);
-
                     let mut drain = args.iter_mut();
                     $(let mut $par = $clone(drain.next().unwrap()); )*
 
@@ -173,7 +158,7 @@ macro_rules! def_register {
 
                     // Map the result
                     Ok(Dynamic::from(r))
-                }), has_context: false }
+                }), has_context: false, is_pure }
             }
         }
 
@@ -184,13 +169,11 @@ macro_rules! def_register {
         > RegisterNativeFunction<($($mark,)*), $n, true, RET, false> for FN {
             #[inline(always)] fn param_types() -> [TypeId;$n] { [$(TypeId::of::<$par>()),*] }
             #[cfg(feature = "metadata")] #[inline(always)] fn param_names() -> [&'static str;$n] { [$(type_name::<$param>()),*] }
-            #[inline(always)] fn into_callable_function(self, fn_name: Identifier, no_const: bool) -> CallableFunction {
+            #[inline(always)] fn into_callable_function(self, fn_name: Identifier, is_pure: bool) -> CallableFunction {
                 CallableFunction::$abi { func: Shared::new(move |ctx: Option<NativeCallContext>, args: &mut FnCallArgs| {
                     let ctx = ctx.unwrap();
 
                     // The arguments are assumed to be of the correct number and types!
-                    check_constant!($abi, $n, fn_name, no_const, args);
-
                     let mut drain = args.iter_mut();
                     $(let mut $par = $clone(drain.next().unwrap()); )*
 
@@ -199,7 +182,7 @@ macro_rules! def_register {
 
                     // Map the result
                     Ok(Dynamic::from(r))
-                }), has_context: true }
+                }), has_context: true, is_pure }
             }
         }
 
@@ -211,17 +194,15 @@ macro_rules! def_register {
             #[inline(always)] fn param_types() -> [TypeId;$n] { [$(TypeId::of::<$par>()),*] }
             #[cfg(feature = "metadata")] #[inline(always)] fn param_names() -> [&'static str;$n] { [$(type_name::<$param>()),*] }
             #[cfg(feature = "metadata")] #[inline(always)] fn return_type_name() -> &'static str { type_name::<RhaiResultOf<RET>>() }
-            #[inline(always)] fn into_callable_function(self, fn_name: Identifier, no_const: bool) -> CallableFunction {
+            #[inline(always)] fn into_callable_function(self, fn_name: Identifier, is_pure: bool) -> CallableFunction {
                 CallableFunction::$abi { func: Shared::new(move |_, args: &mut FnCallArgs| {
                     // The arguments are assumed to be of the correct number and types!
-                    check_constant!($abi, $n, fn_name, no_const, args);
-
                     let mut drain = args.iter_mut();
                     $(let mut $par = $clone(drain.next().unwrap()); )*
 
                     // Call the function with each argument value
                     self($($arg),*).map(Dynamic::from)
-                }), has_context: false }
+                }), has_context: false, is_pure }
             }
         }
 
@@ -233,19 +214,17 @@ macro_rules! def_register {
             #[inline(always)] fn param_types() -> [TypeId;$n] { [$(TypeId::of::<$par>()),*] }
             #[cfg(feature = "metadata")] #[inline(always)] fn param_names() -> [&'static str;$n] { [$(type_name::<$param>()),*] }
             #[cfg(feature = "metadata")] #[inline(always)] fn return_type_name() -> &'static str { type_name::<RhaiResultOf<RET>>() }
-            #[inline(always)] fn into_callable_function(self, fn_name: Identifier, no_const: bool) -> CallableFunction {
+            #[inline(always)] fn into_callable_function(self, fn_name: Identifier, is_pure: bool) -> CallableFunction {
                 CallableFunction::$abi { func: Shared::new(move |ctx: Option<NativeCallContext>, args: &mut FnCallArgs| {
                     let ctx = ctx.unwrap();
 
                     // The arguments are assumed to be of the correct number and types!
-                    check_constant!($abi, $n, fn_name, no_const, args);
-
                     let mut drain = args.iter_mut();
                     $(let mut $par = $clone(drain.next().unwrap()); )*
 
                     // Call the function with each argument value
                     self(ctx, $($arg),*).map(Dynamic::from)
-                }), has_context: true }
+                }), has_context: true, is_pure }
             }
         }
 
diff --git a/src/module/mod.rs b/src/module/mod.rs
index 26dbca16..eeb6874e 100644
--- a/src/module/mod.rs
+++ b/src/module/mod.rs
@@ -1266,6 +1266,7 @@ impl Module {
             CallableFunction::Method {
                 func: Shared::new(f),
                 has_context: true,
+                is_pure: false,
             },
         )
     }
@@ -1303,15 +1304,15 @@ impl Module {
         F: RegisterNativeFunction<A, N, C, T, true>,
     {
         let fn_name = name.into();
-        let no_const = false;
+        let is_pure = true;
 
         #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
-        let no_const = no_const || (F::num_params() == 3 && fn_name == crate::engine::FN_IDX_SET);
+        let is_pure = is_pure && (F::num_params() != 3 || fn_name != crate::engine::FN_IDX_SET);
         #[cfg(not(feature = "no_object"))]
-        let no_const =
-            no_const || (F::num_params() == 2 && fn_name.starts_with(crate::engine::FN_SET));
+        let is_pure =
+            is_pure && (F::num_params() != 2 || !fn_name.starts_with(crate::engine::FN_SET));
 
-        let func = func.into_callable_function(fn_name.clone(), no_const);
+        let func = func.into_callable_function(fn_name.clone(), is_pure);
 
         self.set_fn(
             fn_name,
@@ -1350,7 +1351,7 @@ impl Module {
         F: RegisterNativeFunction<(Mut<A>,), 1, C, T, true> + SendSync + 'static,
     {
         let fn_name = crate::engine::make_getter(name.as_ref());
-        let func = func.into_callable_function(fn_name.clone(), false);
+        let func = func.into_callable_function(fn_name.clone(), true);
 
         self.set_fn(
             fn_name,
@@ -1394,7 +1395,7 @@ impl Module {
         F: RegisterNativeFunction<(Mut<A>, T), 2, C, (), true> + SendSync + 'static,
     {
         let fn_name = crate::engine::make_setter(name.as_ref());
-        let func = func.into_callable_function(fn_name.clone(), true);
+        let func = func.into_callable_function(fn_name.clone(), false);
 
         self.set_fn(
             fn_name,
@@ -1510,7 +1511,7 @@ impl Module {
             FnAccess::Public,
             None,
             F::param_types(),
-            func.into_callable_function(crate::engine::FN_IDX_GET.into(), false),
+            func.into_callable_function(crate::engine::FN_IDX_GET.into(), true),
         )
     }
 
@@ -1571,7 +1572,7 @@ impl Module {
             FnAccess::Public,
             None,
             F::param_types(),
-            func.into_callable_function(crate::engine::FN_IDX_SET.into(), true),
+            func.into_callable_function(crate::engine::FN_IDX_SET.into(), false),
         )
     }
 
@@ -1986,23 +1987,35 @@ impl Module {
     }
 
     /// Get an iterator to the sub-modules in the [`Module`].
-    #[inline]
+    #[inline(always)]
     pub fn iter_sub_modules(&self) -> impl Iterator<Item = (&str, &SharedModule)> {
+        self.iter_sub_modules_raw().map(|(k, m)| (k.as_str(), m))
+    }
+    /// Get an iterator to the sub-modules in the [`Module`].
+    #[inline]
+    pub(crate) fn iter_sub_modules_raw(
+        &self,
+    ) -> impl Iterator<Item = (&Identifier, &SharedModule)> {
         self.modules
             .as_ref()
             .into_iter()
             .flatten()
-            .map(|(k, m)| (k.as_str(), m))
+            .map(|(k, m)| (k, m))
     }
 
     /// Get an iterator to the variables in the [`Module`].
-    #[inline]
+    #[inline(always)]
     pub fn iter_var(&self) -> impl Iterator<Item = (&str, &Dynamic)> {
+        self.iter_var_raw().map(|(k, v)| (k.as_str(), v))
+    }
+    /// Get an iterator to the variables in the [`Module`].
+    #[inline]
+    pub(crate) fn iter_var_raw(&self) -> impl Iterator<Item = (&Identifier, &Dynamic)> {
         self.variables
             .as_ref()
             .into_iter()
             .flatten()
-            .map(|(k, v)| (k.as_str(), v))
+            .map(|(k, v)| (k, v))
     }
 
     /// Get an iterator to the functions in the [`Module`].
diff --git a/src/optimizer.rs b/src/optimizer.rs
index 80e9d5e0..5300fd0c 100644
--- a/src/optimizer.rs
+++ b/src/optimizer.rs
@@ -14,10 +14,9 @@ use crate::func::builtin::get_builtin_binary_op_fn;
 use crate::func::hashing::get_hasher;
 use crate::module::ModuleFlags;
 use crate::tokenizer::Token;
-use crate::types::dynamic::AccessMode;
 use crate::{
-    calc_fn_hash, calc_fn_hash_full, Dynamic, Engine, FnPtr, Identifier, ImmutableString, Position,
-    Scope, StaticVec, AST,
+    calc_fn_hash, calc_fn_hash_full, Dynamic, Engine, FnPtr, ImmutableString, Position, Scope,
+    StaticVec, AST,
 };
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
@@ -54,8 +53,8 @@ impl Default for OptimizationLevel {
 struct OptimizerState<'a> {
     /// Has the [`AST`] been changed during this pass?
     changed: bool,
-    /// Collection of constants to use for eager function evaluations.
-    variables: StaticVec<(Identifier, AccessMode, Option<Dynamic>)>,
+    /// Collection of variables/constants to use for eager function evaluations.
+    variables: StaticVec<(ImmutableString, Option<Dynamic>)>,
     /// Activate constants propagation?
     propagate_constants: bool,
     /// An [`Engine`] instance for eager function evaluation.
@@ -115,14 +114,11 @@ impl<'a> OptimizerState<'a> {
         self.variables.truncate(len);
     }
     /// Add a new variable to the list.
+    ///
+    /// `Some(value)` if constant, `None` or otherwise.
     #[inline(always)]
-    pub fn push_var(
-        &mut self,
-        name: impl Into<Identifier>,
-        access: AccessMode,
-        value: Option<Dynamic>,
-    ) {
-        self.variables.push((name.into(), access, value));
+    pub fn push_var(&mut self, name: ImmutableString, value: Option<Dynamic>) {
+        self.variables.push((name, value));
     }
     /// Look up a constant from the list.
     #[inline]
@@ -131,12 +127,9 @@ impl<'a> OptimizerState<'a> {
             return None;
         }
 
-        for (n, access, value) in self.variables.iter().rev() {
-            if n == name {
-                return match access {
-                    AccessMode::ReadWrite => None,
-                    AccessMode::ReadOnly => value.as_ref(),
-                };
+        for (n, value) in self.variables.iter().rev() {
+            if n.as_str() == name {
+                return value.as_ref();
             }
         }
 
@@ -237,16 +230,13 @@ fn optimize_stmt_block(
                         optimize_expr(&mut x.1, state, false);
 
                         if x.1.is_constant() {
-                            state.push_var(
-                                x.0.as_str(),
-                                AccessMode::ReadOnly,
-                                x.1.get_literal_value(),
-                            );
+                            state
+                                .push_var(x.0.name.clone(), Some(x.1.get_literal_value().unwrap()));
                         }
                     } else {
                         // Add variables into the state
                         optimize_expr(&mut x.1, state, false);
-                        state.push_var(x.0.as_str(), AccessMode::ReadWrite, None);
+                        state.push_var(x.0.name.clone(), None);
                     }
                 }
                 // Optimize the statement
@@ -858,7 +848,7 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
         #[cfg(not(feature = "no_closure"))]
         Stmt::Share(x) => {
             let len = x.len();
-            x.retain(|(v, _, _)| !state.find_constant(v).is_some());
+            x.retain(|(v, _)| !state.find_constant(v).is_some());
             if x.len() != len {
                 state.set_dirty();
             }
@@ -1335,20 +1325,14 @@ impl Engine {
             .iter()
             .rev()
             .flat_map(|m| m.iter_var())
-            .for_each(|(name, value)| {
-                state.push_var(name, AccessMode::ReadOnly, Some(value.clone()))
-            });
+            .for_each(|(name, value)| state.push_var(name.into(), Some(value.clone())));
 
         // Add constants and variables from the scope
         scope
             .into_iter()
             .flat_map(Scope::iter)
             .for_each(|(name, constant, value)| {
-                if constant {
-                    state.push_var(name, AccessMode::ReadOnly, Some(value));
-                } else {
-                    state.push_var(name, AccessMode::ReadWrite, None);
-                }
+                state.push_var(name.into(), if constant { Some(value) } else { None });
             });
 
         optimize_stmt_block(statements, &mut state, true, false, true)
diff --git a/src/parser.rs b/src/parser.rs
index 2300b402..a34c851c 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1728,6 +1728,9 @@ impl Engine {
     ) -> ParseResult<Expr> {
         let mut settings = settings;
 
+        // Break just in case `lhs` is `Expr::Dot` or `Expr::Index`
+        let mut parent_options = ASTFlags::BREAK;
+
         // Tail processing all possible postfix operators
         loop {
             let (tail_token, ..) = input.peek().expect(NEVER_ENDS);
@@ -1842,13 +1845,16 @@ impl Engine {
                     let rhs =
                         self.parse_primary(input, state, lib, settings.level_up()?, options)?;
 
-                    Self::make_dot_expr(state, expr, rhs, ASTFlags::empty(), op_flags, tail_pos)?
+                    Self::make_dot_expr(state, expr, rhs, parent_options, op_flags, tail_pos)?
                 }
                 // Unknown postfix operator
                 (expr, token) => {
                     unreachable!("unknown postfix operator '{}' for {:?}", token, expr)
                 }
-            }
+            };
+
+            // The chain is now extended
+            parent_options = ASTFlags::empty();
         }
 
         // Cache the hash key for namespace-qualified variables
@@ -2431,13 +2437,7 @@ impl Engine {
                 }
 
                 #[cfg(not(feature = "no_custom_syntax"))]
-                Token::Custom(s)
-                    if self
-                        .custom_keywords
-                        .as_ref()
-                        .and_then(|m| m.get(s.as_str()))
-                        .map_or(false, Option::is_some) =>
-                {
+                Token::Custom(s) if self.is_custom_keyword(s.as_str()) => {
                     op_base.hashes = if native_only {
                         FnCallHashes::from_native_only(calc_fn_hash(None, &s, 2))
                     } else {
@@ -3781,9 +3781,9 @@ impl Engine {
         statements.push(Stmt::Share(
             externals
                 .into_iter()
-                .map(|Ident { name, pos }| {
-                    let (index, _) = parent.access_var(&name, lib, pos);
-                    (name, index, pos)
+                .map(|var| {
+                    let (index, _) = parent.access_var(&var.name, lib, var.pos);
+                    (var, index)
                 })
                 .collect::<crate::FnArgsVec<_>>()
                 .into(),
diff --git a/src/tokenizer.rs b/src/tokenizer.rs
index 2e0e009c..0d855cbf 100644
--- a/src/tokenizer.rs
+++ b/src/tokenizer.rs
@@ -2492,7 +2492,7 @@ impl<'a> Iterator for TokenIterator<'a> {
             Some((Token::Reserved(s), pos)) => (match
                 (s.as_str(),
                     #[cfg(not(feature = "no_custom_syntax"))]
-                    self.engine.custom_keywords.as_ref().map_or(false, |m| m.contains_key(&*s)),
+                    self.engine.is_custom_keyword(&*s),
                     #[cfg(feature = "no_custom_syntax")]
                     false
                 )
@@ -2529,7 +2529,7 @@ impl<'a> Iterator for TokenIterator<'a> {
                 #[cfg(feature = "no_custom_syntax")]
                 (.., true) => unreachable!("no custom operators"),
                 // Reserved keyword that is not custom and disabled.
-                (token, false) if self.engine.disabled_symbols.as_ref().map_or(false,|m| m.contains(token)) => {
+                (token, false) if self.engine.is_symbol_disabled(token) => {
                     let msg = format!("reserved {} '{token}' is disabled", if is_valid_identifier(token) { "keyword"} else {"symbol"});
                     Token::LexError(LERR::ImproperSymbol(s.to_string(), msg).into())
                 },
@@ -2538,13 +2538,13 @@ impl<'a> Iterator for TokenIterator<'a> {
             }, pos),
             // Custom keyword
             #[cfg(not(feature = "no_custom_syntax"))]
-            Some((Token::Identifier(s), pos)) if self.engine.custom_keywords.as_ref().map_or(false,|m| m.contains_key(&*s)) => {
+            Some((Token::Identifier(s), pos)) if self.engine.is_custom_keyword(&*s) => {
                 (Token::Custom(s), pos)
             }
             // Custom keyword/symbol - must be disabled
             #[cfg(not(feature = "no_custom_syntax"))]
-            Some((token, pos)) if token.is_literal() && self.engine.custom_keywords.as_ref().map_or(false,|m| m.contains_key(token.literal_syntax())) => {
-                if self.engine.disabled_symbols.as_ref().map_or(false,|m| m.contains(token.literal_syntax())) {
+            Some((token, pos)) if token.is_literal() && self.engine.is_custom_keyword(token.literal_syntax()) => {
+                if self.engine.is_symbol_disabled(token.literal_syntax()) {
                     // Disabled standard keyword/symbol
                     (Token::Custom(Box::new(token.literal_syntax().into())), pos)
                 } else {
@@ -2553,7 +2553,7 @@ impl<'a> Iterator for TokenIterator<'a> {
                 }
             }
             // Disabled symbol
-            Some((token, pos)) if token.is_literal() && self.engine.disabled_symbols.as_ref().map_or(false,|m| m.contains(token.literal_syntax())) => {
+            Some((token, pos)) if token.is_literal() && self.engine.is_symbol_disabled(token.literal_syntax()) => {
                 (Token::Reserved(Box::new(token.literal_syntax().into())), pos)
             }
             // Normal symbol
diff --git a/src/types/dynamic.rs b/src/types/dynamic.rs
index 49cafcf5..acc691a0 100644
--- a/src/types/dynamic.rs
+++ b/src/types/dynamic.rs
@@ -1017,18 +1017,23 @@ impl Dynamic {
     }
     /// Create a [`Dynamic`] from any type.  A [`Dynamic`] value is simply returned as is.
     ///
-    /// # Notes
+    /// # Arrays
     ///
     /// Beware that you need to pass in an [`Array`][crate::Array] type for it to be recognized as
     /// an [`Array`][crate::Array]. A [`Vec<T>`][Vec] does not get automatically converted to an
-    /// [`Array`][crate::Array], but will be a custom type instead (stored as a trait object).  Use
-    /// [`Dynamic::from_array`] to convert a [`Vec<T>`][Vec] into a [`Dynamic`] as an
-    /// [`Array`][crate::Array] value.
+    /// [`Array`][crate::Array], but will be a custom type instead (stored as a trait object).
+    ///
+    /// Use `array.into()` or `array.into_iter()` to convert a [`Vec<T>`][Vec] into a [`Dynamic`] as
+    /// an [`Array`][crate::Array] value.  See the examples for details.
+    ///
+    /// # Hash Maps
     ///
     /// Similarly, passing in a [`HashMap<String, T>`][std::collections::HashMap] or
     /// [`BTreeMap<String, T>`][std::collections::BTreeMap] will not get a [`Map`][crate::Map] but a
-    /// custom type. Again, use [`Dynamic::from_map`] to get a [`Dynamic`] with a [`Map`][crate::Map]
-    /// value.
+    /// custom type.
+    ///
+    /// Again, use `map.into()` to get a [`Dynamic`] with a [`Map`][crate::Map] value.
+    /// See the examples for details.
     ///
     /// # Examples
     ///
@@ -1046,6 +1051,33 @@ impl Dynamic {
     /// let new_result = Dynamic::from(result);
     /// assert_eq!(new_result.type_name(), "string");
     /// assert_eq!(new_result.to_string(), "hello");
+    ///
+    /// # #[cfg(not(feature = "no_index"))]
+    /// # {
+    /// // Arrays - this is a custom object!
+    /// let result = Dynamic::from(vec![1_i64, 2, 3]);
+    /// assert_eq!(result.type_name(), "alloc::vec::Vec<i64>");
+    ///
+    /// // Use '.into()' to convert a Vec<T> into an Array
+    /// let result: Dynamic = vec![1_i64, 2, 3].into();
+    /// assert_eq!(result.type_name(), "array");
+    /// # }
+    ///
+    /// # #[cfg(not(feature = "no_object"))]
+    /// # {
+    /// # use std::collections::HashMap;
+    /// // Hash map
+    /// let mut map = HashMap::new();
+    /// map.insert("a".to_string(), 1_i64);
+    ///
+    /// // This is a custom object!
+    /// let result = Dynamic::from(map.clone());
+    /// assert_eq!(result.type_name(), "std::collections::hash::map::HashMap<alloc::string::String, i64>");
+    ///
+    /// // Use '.into()' to convert a HashMap<String, T> into an object map
+    /// let result: Dynamic = map.into();
+    /// assert_eq!(result.type_name(), "map");
+    /// # }
     /// ```
     #[inline]
     pub fn from<T: Variant + Clone>(value: T) -> Self {
diff --git a/tests/arrays.rs b/tests/arrays.rs
index 8820a54a..d8b24f4f 100644
--- a/tests/arrays.rs
+++ b/tests/arrays.rs
@@ -203,6 +203,22 @@ fn test_arrays() -> Result<(), Box<EvalAltResult>> {
     Ok(())
 }
 
+#[cfg(not(feature = "no_float"))]
+#[cfg(not(feature = "no_object"))]
+#[test]
+fn test_array_chaining() -> Result<(), Box<EvalAltResult>> {
+    let engine = Engine::new();
+
+    assert!(engine.eval::<bool>(
+        "
+            let v = [ PI() ];
+            ( v[0].cos() ).sin() == v[0].cos().sin()
+        "
+    )?);
+
+    Ok(())
+}
+
 #[test]
 fn test_array_index_types() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();
@@ -210,34 +226,25 @@ fn test_array_index_types() -> Result<(), Box<EvalAltResult>> {
     engine.compile("[1, 2, 3][0]['x']")?;
 
     assert!(matches!(
-        engine
-            .compile("[1, 2, 3]['x']")
-            .expect_err("should error")
-            .err_type(),
+        engine.compile("[1, 2, 3]['x']").unwrap_err().err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
 
     #[cfg(not(feature = "no_float"))]
     assert!(matches!(
-        engine
-            .compile("[1, 2, 3][123.456]")
-            .expect_err("should error")
-            .err_type(),
+        engine.compile("[1, 2, 3][123.456]").unwrap_err().err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
 
     assert!(matches!(
-        engine
-            .compile("[1, 2, 3][()]")
-            .expect_err("should error")
-            .err_type(),
+        engine.compile("[1, 2, 3][()]").unwrap_err().err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
 
     assert!(matches!(
         engine
             .compile(r#"[1, 2, 3]["hello"]"#)
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
@@ -245,7 +252,7 @@ fn test_array_index_types() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine
             .compile("[1, 2, 3][true && false]")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
@@ -517,9 +524,9 @@ fn test_arrays_map_reduce() -> Result<(), Box<EvalAltResult>> {
 
     engine.eval::<()>(
         "
-                let x = [1, 2, 3, 2, 1];
-                x.find(|v| v > 4)
-            ",
+            let x = [1, 2, 3, 2, 1];
+            x.find(|v| v > 4)
+        ",
     )?;
 
     assert_eq!(
@@ -534,9 +541,9 @@ fn test_arrays_map_reduce() -> Result<(), Box<EvalAltResult>> {
 
     engine.eval::<()>(
         "
-                let x = [#{alice: 1}, #{bob: 2}, #{clara: 3}];
-                x.find_map(|v| v.dave)
-            ",
+            let x = [#{alice: 1}, #{bob: 2}, #{clara: 3}];
+            x.find_map(|v| v.dave)
+        ",
     )?;
 
     Ok(())
diff --git a/tests/assignments.rs b/tests/assignments.rs
index e2a90d4f..08846845 100644
--- a/tests/assignments.rs
+++ b/tests/assignments.rs
@@ -21,71 +21,44 @@ fn test_assignments_bad_lhs() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();
 
     assert_eq!(
-        *engine
-            .compile("(x+y) = 42;")
-            .expect_err("should error")
-            .err_type(),
+        *engine.compile("(x+y) = 42;").unwrap_err().err_type(),
         ParseErrorType::AssignmentToInvalidLHS(String::new())
     );
     assert_eq!(
-        *engine
-            .compile("foo(x) = 42;")
-            .expect_err("should error")
-            .err_type(),
+        *engine.compile("foo(x) = 42;").unwrap_err().err_type(),
         ParseErrorType::AssignmentToInvalidLHS(String::new())
     );
     assert_eq!(
-        *engine
-            .compile("true = 42;")
-            .expect_err("should error")
-            .err_type(),
+        *engine.compile("true = 42;").unwrap_err().err_type(),
         ParseErrorType::AssignmentToConstant(String::new())
     );
     assert_eq!(
-        *engine
-            .compile("123 = 42;")
-            .expect_err("should error")
-            .err_type(),
+        *engine.compile("123 = 42;").unwrap_err().err_type(),
         ParseErrorType::AssignmentToConstant(String::new())
     );
 
     #[cfg(not(feature = "no_object"))]
     {
         assert_eq!(
-            *engine
-                .compile("x.foo() = 42;")
-                .expect_err("should error")
-                .err_type(),
+            *engine.compile("x.foo() = 42;").unwrap_err().err_type(),
             ParseErrorType::AssignmentToInvalidLHS(String::new())
         );
         assert_eq!(
-            *engine
-                .compile("x.foo().x.y = 42;")
-                .expect_err("should error")
-                .err_type(),
+            *engine.compile("x.foo().x.y = 42;").unwrap_err().err_type(),
             ParseErrorType::AssignmentToInvalidLHS(String::new())
         );
         assert_eq!(
-            *engine
-                .compile("x.y.z.foo() = 42;")
-                .expect_err("should error")
-                .err_type(),
+            *engine.compile("x.y.z.foo() = 42;").unwrap_err().err_type(),
             ParseErrorType::AssignmentToInvalidLHS(String::new())
         );
         #[cfg(not(feature = "no_index"))]
         assert_eq!(
-            *engine
-                .compile("x.foo()[0] = 42;")
-                .expect_err("should error")
-                .err_type(),
+            *engine.compile("x.foo()[0] = 42;").unwrap_err().err_type(),
             ParseErrorType::AssignmentToInvalidLHS(String::new())
         );
         #[cfg(not(feature = "no_index"))]
         assert_eq!(
-            *engine
-                .compile("x[y].z.foo() = 42;")
-                .expect_err("should error")
-                .err_type(),
+            *engine.compile("x[y].z.foo() = 42;").unwrap_err().err_type(),
             ParseErrorType::AssignmentToInvalidLHS(String::new())
         );
     }
diff --git a/tests/closures.rs b/tests/closures.rs
index 0e934c30..a0511456 100644
--- a/tests/closures.rs
+++ b/tests/closures.rs
@@ -47,10 +47,7 @@ fn test_closures() -> Result<(), Box<EvalAltResult>> {
     scope.push("x", 42 as INT);
 
     assert!(matches!(
-        engine
-            .compile_expression("|x| {}")
-            .expect_err("should error")
-            .err_type(),
+        engine.compile_expression("|x| {}").unwrap_err().err_type(),
         ParseErrorType::BadInput(..)
     ));
 
@@ -292,7 +289,7 @@ fn test_closures_data_race() -> Result<(), Box<EvalAltResult>> {
                     a
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataRace(..)
     ));
 
diff --git a/tests/constants.rs b/tests/constants.rs
index bc49e8ee..943b518e 100644
--- a/tests/constants.rs
+++ b/tests/constants.rs
@@ -86,7 +86,7 @@ fn test_constant_mut() -> Result<(), Box<EvalAltResult>> {
                     MY_NUMBER.value = 42;
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorNonPureMethodCallOnConstant(..)
     ));
 
@@ -119,7 +119,7 @@ fn test_constant_mut() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         *engine
             .run_with_scope(&mut scope, "MY_NUMBER.value = 42;")
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorNonPureMethodCallOnConstant(..)
     ));
 
diff --git a/tests/custom_syntax.rs b/tests/custom_syntax.rs
index ec71e904..85072baf 100644
--- a/tests/custom_syntax.rs
+++ b/tests/custom_syntax.rs
@@ -13,11 +13,11 @@ fn test_custom_syntax() -> Result<(), Box<EvalAltResult>> {
     // Disable 'while' and make sure it still works with custom syntax
     engine.disable_symbol("while");
     assert!(matches!(
-        engine.compile("while false {}").expect_err("should error").err_type(),
+        engine.compile("while false {}").unwrap_err().err_type(),
         ParseErrorType::Reserved(err) if err == "while"
     ));
     assert!(matches!(
-        engine.compile("let while = 0").expect_err("should error").err_type(),
+        engine.compile("let while = 0").unwrap_err().err_type(),
         ParseErrorType::Reserved(err) if err == "while"
     ));
 
@@ -127,7 +127,7 @@ fn test_custom_syntax() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         *engine
             .run("let foo = (exec [x<<15] -> { x += 2 } while x < 42) * 10;")
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorRuntime(..)
     ));
 
@@ -195,7 +195,7 @@ fn test_custom_syntax() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(
         *engine
             .register_custom_syntax(["!"], false, |_, _| Ok(Dynamic::UNIT))
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::BadInput(LexError::ImproperSymbol(
             "!".to_string(),
@@ -364,10 +364,7 @@ fn test_custom_syntax_raw() -> Result<(), Box<EvalAltResult>> {
     );
     assert_eq!(engine.eval::<INT>("(hello kitty) + foo")?, 1041);
     assert_eq!(
-        *engine
-            .compile("hello hey")
-            .expect_err("should error")
-            .err_type(),
+        *engine.compile("hello hey").unwrap_err().err_type(),
         ParseErrorType::BadInput(LexError::ImproperSymbol("hey".to_string(), String::new()))
     );
 
diff --git a/tests/data_size.rs b/tests/data_size.rs
index 50f35f50..feb44199 100644
--- a/tests/data_size.rs
+++ b/tests/data_size.rs
@@ -15,7 +15,7 @@ fn test_max_string_size() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(
         *engine
             .compile(r#"let x = "hello, world!";"#)
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::LiteralTooLarge("Length of string".to_string(), 10)
     );
@@ -23,7 +23,7 @@ fn test_max_string_size() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(
         *engine
             .compile(r#"let x = "朝に紅顔、暮に白骨";"#)
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::LiteralTooLarge("Length of string".to_string(), 10)
     );
@@ -37,7 +37,7 @@ fn test_max_string_size() -> Result<(), Box<EvalAltResult>> {
                     x + y
                 "#
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -51,7 +51,7 @@ fn test_max_string_size() -> Result<(), Box<EvalAltResult>> {
                     x
                 "#
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -83,7 +83,7 @@ fn test_max_array_size() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(
         *engine
             .compile("let x = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15];")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::LiteralTooLarge("Size of array literal".to_string(), 10)
     );
@@ -97,7 +97,7 @@ fn test_max_array_size() -> Result<(), Box<EvalAltResult>> {
                     x + y
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -130,7 +130,7 @@ fn test_max_array_size() -> Result<(), Box<EvalAltResult>> {
                     }
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -142,7 +142,7 @@ fn test_max_array_size() -> Result<(), Box<EvalAltResult>> {
                     loop { x[0] = x; }
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -168,7 +168,7 @@ fn test_max_array_size() -> Result<(), Box<EvalAltResult>> {
                     x
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -190,7 +190,7 @@ fn test_max_array_size() -> Result<(), Box<EvalAltResult>> {
                     [x, x, x, x]
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -203,7 +203,7 @@ fn test_max_array_size() -> Result<(), Box<EvalAltResult>> {
                     [x, x, x, x]
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -217,7 +217,7 @@ fn test_max_array_size() -> Result<(), Box<EvalAltResult>> {
                     [z, z, z]
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -265,7 +265,7 @@ fn test_max_map_size() -> Result<(), Box<EvalAltResult>> {
             .compile(
                 "let x = #{a:1,b:2,c:3,d:4,e:5,f:6,g:7,h:8,i:9,j:10,k:11,l:12,m:13,n:14,o:15};"
             )
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::LiteralTooLarge(
             "Number of properties in object map literal".to_string(),
@@ -281,7 +281,7 @@ fn test_max_map_size() -> Result<(), Box<EvalAltResult>> {
                     loop { x.a = x; }
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -294,7 +294,7 @@ fn test_max_map_size() -> Result<(), Box<EvalAltResult>> {
                     x + y
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -306,7 +306,7 @@ fn test_max_map_size() -> Result<(), Box<EvalAltResult>> {
                     #{u:x, v:x, w:x, z:x}
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
@@ -319,7 +319,7 @@ fn test_max_map_size() -> Result<(), Box<EvalAltResult>> {
                     #{u:x, v:x, w:x, z:x}
                 "
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorDataTooLarge(..)
     ));
 
diff --git a/tests/eval.rs b/tests/eval.rs
index a7b834f9..bd55e72f 100644
--- a/tests/eval.rs
+++ b/tests/eval.rs
@@ -169,7 +169,7 @@ fn test_eval_disabled() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine
             .compile(r#"eval("40 + 2")"#)
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::BadInput(LexError::ImproperSymbol(err, ..)) if err == "eval"
     ));
diff --git a/tests/fn_ptr.rs b/tests/fn_ptr.rs
index 1e2baa84..1d587e2b 100644
--- a/tests/fn_ptr.rs
+++ b/tests/fn_ptr.rs
@@ -72,7 +72,7 @@ fn test_fn_ptr() -> Result<(), Box<EvalAltResult>> {
                     x
                 "#
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorInFunctionCall(fn_name, _, err, ..)
             if fn_name == "foo" && matches!(*err, EvalAltResult::ErrorUnboundThis(..))
     ));
diff --git a/tests/functions.rs b/tests/functions.rs
index a079bbdd..ef873abd 100644
--- a/tests/functions.rs
+++ b/tests/functions.rs
@@ -93,7 +93,7 @@ fn test_functions_global_module() -> Result<(), Box<EvalAltResult>> {
                 const ANSWER = 42;
                 foo()
             }
-        ").expect_err("should error"),
+        ").unwrap_err(),
         EvalAltResult::ErrorInFunctionCall(.., err, _)
             if matches!(&*err, EvalAltResult::ErrorVariableNotFound(v, ..) if v == "global::ANSWER")
     ));
@@ -112,7 +112,7 @@ fn test_functions_global_module() -> Result<(), Box<EvalAltResult>> {
                 const LOCAL_VALUE = 42;
                 global::LOCAL_VALUE
             });
-        ").expect_err("should error"),
+        ").unwrap_err(),
         EvalAltResult::ErrorInFunctionCall(.., err, _)
             if matches!(&*err, EvalAltResult::ErrorVariableNotFound(v, ..) if v == "global::LOCAL_VALUE")
     ));
diff --git a/tests/internal_fn.rs b/tests/internal_fn.rs
index ddd8ff76..f440e479 100644
--- a/tests/internal_fn.rs
+++ b/tests/internal_fn.rs
@@ -109,7 +109,7 @@ fn test_internal_fn_overloading() -> Result<(), Box<EvalAltResult>> {
                     fn abc(x) { x - 42 }
                 "
             )
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::FnDuplicatedDefinition("abc".to_string(), 1)
     );
@@ -125,7 +125,7 @@ fn test_internal_fn_params() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(
         *engine
             .compile("fn hello(x, x) { x }")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::FnDuplicatedParam("hello".to_string(), "x".to_string())
     );
@@ -169,7 +169,7 @@ fn test_function_pointers() -> Result<(), Box<EvalAltResult>> {
 
     #[cfg(not(feature = "no_object"))]
     assert!(matches!(
-        *engine.eval::<INT>(r#"let f = Fn("abc"); f.call(0)"#).expect_err("should error"),
+        *engine.eval::<INT>(r#"let f = Fn("abc"); f.call(0)"#).unwrap_err(),
         EvalAltResult::ErrorFunctionNotFound(f, ..) if f.starts_with("abc (")
     ));
 
@@ -247,7 +247,7 @@ fn test_internal_fn_bang() -> Result<(), Box<EvalAltResult>> {
                     y.foo!();
                 "
             )
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::MalformedCapture(..)
     ));
diff --git a/tests/looping.rs b/tests/looping.rs
index e011eb6b..191b7e85 100644
--- a/tests/looping.rs
+++ b/tests/looping.rs
@@ -27,10 +27,7 @@ fn test_loop() -> Result<(), Box<EvalAltResult>> {
     );
 
     assert_eq!(
-        *engine
-            .compile("let x = 0; break;")
-            .expect_err("should error")
-            .err_type(),
+        *engine.compile("let x = 0; break;").unwrap_err().err_type(),
         ParseErrorType::LoopBreak
     );
 
@@ -38,7 +35,7 @@ fn test_loop() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(
         *engine
             .compile("loop { let f = || { break;  } }")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::LoopBreak
     );
@@ -46,7 +43,7 @@ fn test_loop() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(
         *engine
             .compile("let x = 0; if x > 0 { continue; }")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::LoopBreak
     );
diff --git a/tests/maps.rs b/tests/maps.rs
index 2bfab623..d72b6356 100644
--- a/tests/maps.rs
+++ b/tests/maps.rs
@@ -52,7 +52,7 @@ b`: 1}; y["a\nb"]
     assert!(matches!(
         *engine
             .eval::<INT>("let y = #{`a${1}`: 1}; y.a1")
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorParsing(ParseErrorType::PropertyExpected, ..)
     ));
 
@@ -116,7 +116,7 @@ fn test_map_prop() -> Result<(), Box<EvalAltResult>> {
     engine.set_fail_on_invalid_map_property(true);
 
     assert!(
-        matches!(*engine.eval::<()>("let x = #{a: 42}; x.b").expect_err("should error"),
+        matches!(*engine.eval::<()>("let x = #{a: 42}; x.b").unwrap_err(),
             EvalAltResult::ErrorPropertyNotFound(prop, _) if prop == "b"
         )
     );
@@ -134,7 +134,7 @@ fn test_map_index_types() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine
             .compile("#{a:1, b:2, c:3}['x']")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
@@ -142,7 +142,7 @@ fn test_map_index_types() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine
             .compile("#{a:1, b:2, c:3}[1]")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
@@ -151,7 +151,7 @@ fn test_map_index_types() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine
             .compile("#{a:1, b:2, c:3}[123.456]")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
@@ -159,7 +159,7 @@ fn test_map_index_types() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine
             .compile("#{a:1, b:2, c:3}[()]")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
@@ -167,7 +167,7 @@ fn test_map_index_types() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine
             .compile("#{a:1, b:2, c:3}[true && false]")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::MalformedIndexExpr(..)
     ));
@@ -272,38 +272,32 @@ fn test_map_json() -> Result<(), Box<EvalAltResult>> {
     engine.parse_json(json, true)?;
 
     assert!(matches!(
-        *engine.parse_json("123", true).expect_err("should error"),
+        *engine.parse_json("123", true).unwrap_err(),
         EvalAltResult::ErrorMismatchOutputType(..)
     ));
 
     assert!(matches!(
-        *engine.parse_json("{a:42}", true).expect_err("should error"),
+        *engine.parse_json("{a:42}", true).unwrap_err(),
         EvalAltResult::ErrorParsing(..)
     ));
 
     assert!(matches!(
-        *engine
-            .parse_json("#{a:123}", true)
-            .expect_err("should error"),
+        *engine.parse_json("#{a:123}", true).unwrap_err(),
         EvalAltResult::ErrorParsing(..)
     ));
 
     assert!(matches!(
-        *engine.parse_json("{a:()}", true).expect_err("should error"),
+        *engine.parse_json("{a:()}", true).unwrap_err(),
         EvalAltResult::ErrorParsing(..)
     ));
 
     assert!(matches!(
-        *engine
-            .parse_json("#{a:123+456}", true)
-            .expect_err("should error"),
+        *engine.parse_json("#{a:123+456}", true).unwrap_err(),
         EvalAltResult::ErrorParsing(..)
     ));
 
     assert!(matches!(
-        *engine
-            .parse_json("{a:`hello${world}`}", true)
-            .expect_err("should error"),
+        *engine.parse_json("{a:`hello${world}`}", true).unwrap_err(),
         EvalAltResult::ErrorParsing(..)
     ));
 
diff --git a/tests/method_call.rs b/tests/method_call.rs
index 577447e7..75c19792 100644
--- a/tests/method_call.rs
+++ b/tests/method_call.rs
@@ -127,7 +127,7 @@ fn test_method_call_typed() -> Result<(), Box<EvalAltResult>> {
                     foo(1000);
                 "#
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorFunctionNotFound(f, ..) if f.starts_with("foo")
     ));
 
@@ -142,7 +142,7 @@ fn test_method_call_typed() -> Result<(), Box<EvalAltResult>> {
                     x.foo(1000);
                 "#
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorFunctionNotFound(f, ..) if f.starts_with("foo")
     ));
 
diff --git a/tests/mismatched_op.rs b/tests/mismatched_op.rs
index 85d31857..dd094a45 100644
--- a/tests/mismatched_op.rs
+++ b/tests/mismatched_op.rs
@@ -36,21 +36,21 @@ fn test_mismatched_op_custom_type() -> Result<(), Box<EvalAltResult>> {
             let x = new_ts();
             let y = new_ts();
             x == y
-        ").expect_err("should error"),
+        ").unwrap_err(),
         EvalAltResult::ErrorFunctionNotFound(f, ..) if f == "== (TestStruct, TestStruct)"));
 
     assert!(
-        matches!(*engine.eval::<bool>("new_ts() == 42").expect_err("should error"),
+        matches!(*engine.eval::<bool>("new_ts() == 42").unwrap_err(),
         EvalAltResult::ErrorFunctionNotFound(f, ..) if f.starts_with("== (TestStruct, "))
     );
 
     assert!(matches!(
-        *engine.eval::<INT>("60 + new_ts()").expect_err("should error"),
+        *engine.eval::<INT>("60 + new_ts()").unwrap_err(),
         EvalAltResult::ErrorFunctionNotFound(f, ..) if f == format!("+ ({}, TestStruct)", std::any::type_name::<INT>())
     ));
 
     assert!(matches!(
-        *engine.eval::<TestStruct>("42").expect_err("should error"),
+        *engine.eval::<TestStruct>("42").unwrap_err(),
         EvalAltResult::ErrorMismatchOutputType(need, actual, ..)
             if need == "TestStruct" && actual == std::any::type_name::<INT>()
     ));
diff --git a/tests/modules.rs b/tests/modules.rs
index 447917a3..f296d78b 100644
--- a/tests/modules.rs
+++ b/tests/modules.rs
@@ -227,7 +227,7 @@ fn test_module_resolver() -> Result<(), Box<EvalAltResult>> {
                         sum
                     "#
                 )
-                .expect_err("should error"),
+                .unwrap_err(),
             EvalAltResult::ErrorTooManyModules(..)
         ));
 
@@ -250,7 +250,7 @@ fn test_module_resolver() -> Result<(), Box<EvalAltResult>> {
                         sum
                     "#
                 )
-                .expect_err("should error"),
+                .unwrap_err(),
             EvalAltResult::ErrorInFunctionCall(fn_name, ..) if fn_name == "foo"
         ));
 
@@ -403,7 +403,7 @@ fn test_module_from_ast() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         *engine
             .run(r#"import "testing" as ttt; ttt::hidden()"#)
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorFunctionNotFound(fn_name, ..) if fn_name == "ttt::hidden ()"
     ));
 
@@ -415,13 +415,13 @@ fn test_module_export() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();
 
     assert!(matches!(
-        engine.compile("let x = 10; { export x; }").expect_err("should error"),
+        engine.compile("let x = 10; { export x; }").unwrap_err(),
         ParseError(x, ..) if *x == ParseErrorType::WrongExport
     ));
 
     #[cfg(not(feature = "no_function"))]
     assert!(matches!(
-        engine.compile("fn abc(x) { export x; }").expect_err("should error"),
+        engine.compile("fn abc(x) { export x; }").unwrap_err(),
         ParseError(x, ..) if *x == ParseErrorType::WrongExport
     ));
 
diff --git a/tests/operations.rs b/tests/operations.rs
index c4eb37ab..b179e3e5 100644
--- a/tests/operations.rs
+++ b/tests/operations.rs
@@ -18,7 +18,7 @@ fn test_max_operations() -> Result<(), Box<EvalAltResult>> {
     engine.run("let x = 0; while x < 20 { x += 1; }")?;
 
     assert!(matches!(
-        *engine.run("for x in 0..500 {}").expect_err("should error"),
+        *engine.run("for x in 0..500 {}").unwrap_err(),
         EvalAltResult::ErrorTooManyOperations(..)
     ));
 
@@ -41,9 +41,7 @@ fn test_max_operations_literal() -> Result<(), Box<EvalAltResult>> {
 
     #[cfg(not(feature = "no_index"))]
     assert!(matches!(
-        *engine
-            .run("[1, 2, 3, 4, 5, 6, 7, 8, 9]")
-            .expect_err("should error"),
+        *engine.run("[1, 2, 3, 4, 5, 6, 7, 8, 9]").unwrap_err(),
         EvalAltResult::ErrorTooManyOperations(..)
     ));
 
@@ -54,7 +52,7 @@ fn test_max_operations_literal() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         *engine
             .run("#{a:1, b:2, c:3, d:4, e:5, f:6, g:7, h:8, i:9}")
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorTooManyOperations(..)
     ));
 
@@ -110,7 +108,7 @@ fn test_max_operations_functions() -> Result<(), Box<EvalAltResult>> {
                     }
                 "#,
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorTooManyOperations(..)
     ));
 
@@ -137,7 +135,7 @@ fn test_max_operations_eval() -> Result<(), Box<EvalAltResult>> {
                     eval(script);
                 "#
             )
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorInFunctionCall(.., err, _) if matches!(*err, EvalAltResult::ErrorTooManyOperations(..))
     ));
 
@@ -162,7 +160,7 @@ fn test_max_operations_progress() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         *engine
             .run("for x in 0..500 {}")
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorTerminated(x, ..) if x.as_int()? == 42
     ));
 
diff --git a/tests/ops.rs b/tests/ops.rs
index ce6c5611..7c8e0077 100644
--- a/tests/ops.rs
+++ b/tests/ops.rs
@@ -26,17 +26,17 @@ fn test_ops_other_number_types() -> Result<(), Box<EvalAltResult>> {
     scope.push("x", 42_u16);
 
     assert!(matches!(
-        *engine.eval_with_scope::<bool>(&mut scope, "x == 42").expect_err("should error"),
+        *engine.eval_with_scope::<bool>(&mut scope, "x == 42").unwrap_err(),
         EvalAltResult::ErrorFunctionNotFound(f, ..) if f.starts_with("== (u16,")
     ));
     #[cfg(not(feature = "no_float"))]
     assert!(matches!(
-        *engine.eval_with_scope::<bool>(&mut scope, "x == 42.0").expect_err("should error"),
+        *engine.eval_with_scope::<bool>(&mut scope, "x == 42.0").unwrap_err(),
         EvalAltResult::ErrorFunctionNotFound(f, ..) if f.starts_with("== (u16,")
     ));
 
     assert!(
-        matches!(*engine.eval_with_scope::<bool>(&mut scope, r#"x == "hello""#).expect_err("should error"),
+        matches!(*engine.eval_with_scope::<bool>(&mut scope, r#"x == "hello""#).unwrap_err(),
             EvalAltResult::ErrorFunctionNotFound(f, ..) if f.starts_with("== (u16,")
         )
     );
diff --git a/tests/optimizer.rs b/tests/optimizer.rs
index 80b8ccf1..4d69d6ea 100644
--- a/tests/optimizer.rs
+++ b/tests/optimizer.rs
@@ -182,9 +182,44 @@ fn test_optimizer_reoptimize() -> Result<(), Box<EvalAltResult>> {
     let scope: Scope = ast.iter_literal_variables(true, false).collect();
     let ast = engine.optimize_ast(&scope, ast, OptimizationLevel::Simple);
 
-    println!("{ast:#?}");
-
     assert_eq!(engine.eval_ast::<INT>(&ast)?, 84);
 
     Ok(())
 }
+
+#[test]
+fn test_optimizer_full() -> Result<(), Box<EvalAltResult>> {
+    #[derive(Debug, Clone)]
+    struct TestStruct(INT);
+
+    const SCRIPT: &str = "
+        const FOO = ts(40) + ts(2);
+        value(FOO)
+    ";
+
+    let mut engine = Engine::new();
+    let mut scope = Scope::new();
+
+    engine.set_optimization_level(OptimizationLevel::Full);
+
+    engine
+        .register_type_with_name::<TestStruct>("TestStruct")
+        .register_fn("ts", |n: INT| TestStruct(n))
+        .register_fn("value", |ts: &mut TestStruct| ts.0)
+        .register_fn("+", |ts1: &mut TestStruct, ts2: TestStruct| {
+            TestStruct(ts1.0 + ts2.0)
+        });
+
+    let ast = engine.compile(SCRIPT)?;
+
+    #[cfg(feature = "internals")]
+    assert_eq!(ast.statements().len(), 2);
+
+    assert_eq!(engine.eval_ast_with_scope::<INT>(&mut scope, &ast)?, 42);
+
+    assert_eq!(scope.len(), 1);
+
+    assert_eq!(scope.get_value::<TestStruct>("FOO").unwrap().0, 42);
+
+    Ok(())
+}
diff --git a/tests/plugins.rs b/tests/plugins.rs
index ab752bc3..7b1214cb 100644
--- a/tests/plugins.rs
+++ b/tests/plugins.rs
@@ -118,7 +118,7 @@ fn test_plugins_package() -> Result<(), Box<EvalAltResult>> {
         engine.run("const A = [1, 2, 3]; A.no_effect = 42;")?;
 
         assert!(
-            matches!(*engine.run("const A = [1, 2, 3]; A.test(42);").expect_err("should error"),
+            matches!(*engine.run("const A = [1, 2, 3]; A.test(42);").unwrap_err(),
             EvalAltResult::ErrorNonPureMethodCallOnConstant(x, ..) if x == "test")
         )
     }
diff --git a/tests/stack.rs b/tests/stack.rs
index a63a5dbd..49e28224 100644
--- a/tests/stack.rs
+++ b/tests/stack.rs
@@ -28,7 +28,7 @@ fn test_stack_overflow_fn_calls() -> Result<(), Box<EvalAltResult>> {
                 ",
                 max + 1
             ))
-            .expect_err("should error"),
+            .unwrap_err(),
         EvalAltResult::ErrorStackOverflow(..)
     ));
 
@@ -44,7 +44,7 @@ fn test_stack_overflow_parsing() -> Result<(), Box<EvalAltResult>> {
             "
                 let a = (1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+(1+1)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))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             "
-        ).expect_err("should error").0,
+        ).unwrap_err().0,
          ParseErrorType::ExprTooDeep
     );
 
@@ -71,7 +71,7 @@ fn test_stack_overflow_parsing() -> Result<(), Box<EvalAltResult>> {
                     1 + 2
                 "
             )
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::ExprTooDeep
     );
@@ -113,7 +113,7 @@ fn test_stack_overflow_parsing() -> Result<(), Box<EvalAltResult>> {
                     1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 0
                 "
             )
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::ExprTooDeep
     );
diff --git a/tests/string.rs b/tests/string.rs
index 37988600..6b150b96 100644
--- a/tests/string.rs
+++ b/tests/string.rs
@@ -116,7 +116,7 @@ fn test_string_mut() -> Result<(), Box<EvalAltResult>> {
     assert_eq!(engine.eval::<INT>(r#"foo("hello")"#)?, 5);
     assert_eq!(engine.eval::<INT>(r#"bar("hello")"#)?, 5);
     assert!(
-        matches!(*engine.eval::<INT>(r#"baz("hello")"#).expect_err("should error"),
+        matches!(*engine.eval::<INT>(r#"baz("hello")"#).unwrap_err(),
             EvalAltResult::ErrorFunctionNotFound(f, ..) if f == "baz (&str | ImmutableString | String)"
         )
     );
diff --git a/tests/switch.rs b/tests/switch.rs
index f37dacc0..67569b5d 100644
--- a/tests/switch.rs
+++ b/tests/switch.rs
@@ -110,7 +110,7 @@ fn test_switch_errors() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine
             .compile("switch x { _ => 123, 1 => 42 }")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::WrongSwitchDefaultCase
     ));
@@ -174,7 +174,7 @@ fn test_switch_condition() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine
             .compile("switch x { 1 => 123, _ if true => 42 }")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::WrongSwitchCaseCondition
     ));
@@ -269,14 +269,14 @@ fn test_switch_ranges() -> Result<(), Box<EvalAltResult>> {
     assert!(matches!(
         engine.compile(
             "switch x { 10..20 => (), 20..=42 => 'a', 25..45 => 'z', 42 => 'x', 30..100 => true }"
-        ).expect_err("should error").err_type(),
+        ).unwrap_err().err_type(),
         ParseErrorType::WrongSwitchIntegerCase
     ));
     #[cfg(not(feature = "no_float"))]
     assert!(matches!(
         engine.compile(
             "switch x { 10..20 => (), 20..=42 => 'a', 25..45 => 'z', 42.0 => 'x', 30..100 => true }"
-        ).expect_err("should error").err_type(),
+        ).unwrap_err().err_type(),
         ParseErrorType::WrongSwitchIntegerCase
     ));
     assert_eq!(
diff --git a/tests/tokens.rs b/tests/tokens.rs
index f6fac1aa..9a7b7d89 100644
--- a/tests/tokens.rs
+++ b/tests/tokens.rs
@@ -9,7 +9,7 @@ fn test_tokens_disabled() {
     assert!(matches!(
         engine
             .compile("let x = if true { 42 } else { 0 };")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::Reserved(err) if err == "if"
     ));
@@ -19,13 +19,13 @@ fn test_tokens_disabled() {
     assert_eq!(
         *engine
             .compile("let x = 40 + 2; x += 1;")
-            .expect_err("should error")
+            .unwrap_err()
             .err_type(),
         ParseErrorType::UnknownOperator("+=".to_string())
     );
 
     assert!(matches!(
-        engine.compile("let x = += 0;").expect_err("should error").err_type(),
+        engine.compile("let x = += 0;").unwrap_err().err_type(),
         ParseErrorType::Reserved(err) if err == "+="
     ));
 }
diff --git a/tests/unit.rs b/tests/unit.rs
index d2abd3c2..04c078bd 100644
--- a/tests/unit.rs
+++ b/tests/unit.rs
@@ -17,6 +17,6 @@ fn test_unit_eq() -> Result<(), Box<EvalAltResult>> {
 #[test]
 fn test_unit_with_spaces() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();
-    let _ = engine.run("let x = ( ); x").expect_err("should error");
+    let _ = engine.run("let x = ( ); x").unwrap_err();
     Ok(())
 }
diff --git a/tests/var_scope.rs b/tests/var_scope.rs
index 32db7db7..5a3120ba 100644
--- a/tests/var_scope.rs
+++ b/tests/var_scope.rs
@@ -209,7 +209,7 @@ fn test_var_resolver() -> Result<(), Box<EvalAltResult>> {
 
     assert_eq!(engine.eval_with_scope::<INT>(&mut scope, "chameleon")?, 1);
     assert!(
-        matches!(*engine.eval_with_scope::<INT>(&mut scope, "DO_NOT_USE").expect_err("should error"),
+        matches!(*engine.eval_with_scope::<INT>(&mut scope, "DO_NOT_USE").unwrap_err(),
         EvalAltResult::ErrorVariableNotFound(n, ..) if n == "DO_NOT_USE")
     );
 
@@ -235,7 +235,7 @@ fn test_var_def_filter() -> Result<(), Box<EvalAltResult>> {
     );
 
     assert!(matches!(
-        engine.compile("let x = 42;").expect_err("should error").err_type(),
+        engine.compile("let x = 42;").unwrap_err().err_type(),
         ParseErrorType::ForbiddenVariable(s) if s == "x"
     ));
     assert!(matches!(
diff --git a/tools/README.md b/tools/README.md
index ff8fe844..9b96f6cc 100644
--- a/tools/README.md
+++ b/tools/README.md
@@ -1,7 +1,9 @@
 Build Tools
 ===========
 
-| File           | Description                                 |
-| -------------- | ------------------------------------------- |
-| `keywords.txt` | Input file for GNU gperf for the tokenizer. |
-| `reserved.txt` | Input file for GNU gperf for the tokenizer. |
+This directory contains input files for various build tools required for building Rhai.
+
+| File           | Build tool  | Description                                                        |
+| -------------- | :---------: | ------------------------------------------------------------------ |
+| `keywords.txt` | GNU `gperf` | Input file for the tokenizer &ndash; keywords recognition.         |
+| `reserved.txt` | GNU `gperf` | Input file for the tokenizer &ndash; reserved symbols recognition. |