diff --git a/CHANGELOG.md b/CHANGELOG.md
index 136c1fd9..7627368d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,10 +6,17 @@ Version 1.14.0
 
 The code hacks that attempt to optimize branch prediction performance are removed because benchmarks do not show any material speed improvements.
 
+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.
+
 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)`
 
 
 Version 1.13.0
diff --git a/scripts/function_decl5.rhai b/scripts/function_decl5.rhai
new file mode 100644
index 00000000..65a4c111
--- /dev/null
+++ b/scripts/function_decl5.rhai
@@ -0,0 +1,35 @@
+//! This script defines multiple versions of the same function
+//! for use as method with different data types.
+
+// For strings
+fn string.calc(x) {
+    this.len + x
+}
+// For integers
+fn int.calc(x) {
+    this * x
+}
+// For booleans
+fn bool.calc(x) {
+    if this { x } else { 0}
+}
+// For arrays
+fn array.calc(x) {
+    this.len + x
+}
+// For object maps
+fn map.calc(x) {
+    this[x]
+}
+// Catch-all
+fn calc(x) {
+    `${this}: ${x}`
+}
+
+print("hello".calc(42));                // 47
+print(42.calc(42));                     // 1764
+print(true.calc(42));                   // 42
+print(false.calc(42));                  // 0
+print([1,2,3].calc(42));                // 45
+print(#{"a": 1, "b": 2}.calc("b"));     // 2
+print('x'.calc(42));                    // x: 42
diff --git a/src/api/call_fn.rs b/src/api/call_fn.rs
index 07ea0c99..120c4f4c 100644
--- a/src/api/call_fn.rs
+++ b/src/api/call_fn.rs
@@ -233,7 +233,7 @@ impl Engine {
         let rewind_scope = options.rewind_scope;
 
         let result = if options.eval_ast && !statements.is_empty() {
-            auto_restore! {
+            defer! {
                 scope if rewind_scope => rewind;
                 let orig_scope_len = scope.len();
             }
diff --git a/src/api/custom_syntax.rs b/src/api/custom_syntax.rs
index acd01195..e5dfb56c 100644
--- a/src/api/custom_syntax.rs
+++ b/src/api/custom_syntax.rs
@@ -261,12 +261,12 @@ impl Engine {
                     // Make it a custom keyword/symbol if it is disabled or reserved
                     if (self
                         .disabled_symbols
-                        .as_deref()
+                        .as_ref()
                         .map_or(false, |m| m.contains(s))
                         || token.as_ref().map_or(false, Token::is_reserved))
                         && !self
                             .custom_keywords
-                            .as_deref()
+                            .as_ref()
                             .map_or(false, |m| m.contains_key(s))
                     {
                         self.custom_keywords
@@ -281,7 +281,7 @@ impl Engine {
                     && token.as_ref().map_or(false, Token::is_standard_keyword)
                     && !self
                         .disabled_symbols
-                        .as_deref()
+                        .as_ref()
                         .map_or(false, |m| m.contains(s)) =>
                 {
                     return Err(LexError::ImproperSymbol(
@@ -301,12 +301,12 @@ impl Engine {
                     // Make it a custom keyword/symbol if it is disabled or reserved
                     if self
                         .disabled_symbols
-                        .as_deref()
+                        .as_ref()
                         .map_or(false, |m| m.contains(s))
                         || (token.as_ref().map_or(false, Token::is_reserved)
                             && !self
                                 .custom_keywords
-                                .as_deref()
+                                .as_ref()
                                 .map_or(false, |m| m.contains_key(s)))
                     {
                         self.custom_keywords
diff --git a/src/api/definitions/builtin-functions.d.rhai b/src/api/definitions/builtin-functions.d.rhai
index 93d07df3..0ccab0d0 100644
--- a/src/api/definitions/builtin-functions.d.rhai
+++ b/src/api/definitions/builtin-functions.d.rhai
@@ -112,6 +112,21 @@ fn curry(fn_ptr: FnPtr, ...args: ?) -> FnPtr;
 /// ```
 fn is_def_fn(fn_name: String, num_params: int) -> bool;
 
+/// Return `true` if a script-defined function exists with a specified name and
+/// number of parameters, bound to a specified type for `this`.
+/// 
+/// # Example
+/// 
+/// ```rhai
+/// // A method that requires `this` to be `MyType`
+/// fn MyType.foo(x) { }
+/// 
+/// print(is_def_fn("MyType", "foo", 1));   // prints true
+/// print(is_def_fn("foo", 1));             // prints false
+/// print(is_def_fn("MyType", "foo", 2));   // prints false
+/// ```
+fn is_def_fn(this_type: String, fn_name: String, num_params: int) -> bool;
+
 /// Return `true` if a variable matching a specified name is defined.
 /// 
 /// # Example
diff --git a/src/api/definitions/mod.rs b/src/api/definitions/mod.rs
index a34a5ac5..69224b27 100644
--- a/src/api/definitions/mod.rs
+++ b/src/api/definitions/mod.rs
@@ -372,7 +372,7 @@ impl Definitions<'_> {
         let mut m = self
             .engine
             .global_sub_modules
-            .as_deref()
+            .as_ref()
             .into_iter()
             .flatten()
             .map(move |(name, module)| {
@@ -461,7 +461,7 @@ impl Module {
                     || def
                         .engine
                         .custom_keywords
-                        .as_deref()
+                        .as_ref()
                         .map_or(false, |m| m.contains_key(f.metadata.name.as_str()));
 
                 f.write_definition(writer, def, operator)?;
diff --git a/src/api/eval.rs b/src/api/eval.rs
index 2c93b182..60a9b816 100644
--- a/src/api/eval.rs
+++ b/src/api/eval.rs
@@ -242,7 +242,7 @@ impl Engine {
             ast.resolver().cloned(),
         );
 
-        auto_restore! { global => move |g| {
+        defer! { global => move |g| {
             #[cfg(not(feature = "no_module"))]
             {
                 g.embedded_module_resolver = orig_embedded_module_resolver;
diff --git a/src/api/formatting.rs b/src/api/formatting.rs
index 07441f49..7fb7a376 100644
--- a/src/api/formatting.rs
+++ b/src/api/formatting.rs
@@ -208,7 +208,7 @@ impl Engine {
                 #[cfg(not(feature = "no_module"))]
                 return self
                     .global_sub_modules
-                    .as_deref()
+                    .as_ref()
                     .into_iter()
                     .flatten()
                     .find_map(|(_, m)| m.get_custom_type(name));
@@ -243,7 +243,7 @@ impl Engine {
                 #[cfg(not(feature = "no_module"))]
                 return self
                     .global_sub_modules
-                    .as_deref()
+                    .as_ref()
                     .into_iter()
                     .flatten()
                     .find_map(|(_, m)| m.get_custom_type(name));
diff --git a/src/api/mod.rs b/src/api/mod.rs
index a2cf21ce..21238f5a 100644
--- a/src/api/mod.rs
+++ b/src/api/mod.rs
@@ -171,7 +171,7 @@ impl Engine {
             Some(token) if token.is_standard_keyword() => {
                 if !self
                     .disabled_symbols
-                    .as_deref()
+                    .as_ref()
                     .map_or(false, |m| m.contains(token.literal_syntax()))
                 {
                     return Err(format!("'{keyword}' is a reserved keyword"));
@@ -181,7 +181,7 @@ impl Engine {
             Some(token) if token.is_standard_symbol() => {
                 if !self
                     .disabled_symbols
-                    .as_deref()
+                    .as_ref()
                     .map_or(false, |m| m.contains(token.literal_syntax()))
                 {
                     return Err(format!("'{keyword}' is a reserved operator"));
@@ -191,7 +191,7 @@ impl Engine {
             Some(token)
                 if !self
                     .disabled_symbols
-                    .as_deref()
+                    .as_ref()
                     .map_or(false, |m| m.contains(token.literal_syntax())) =>
             {
                 return Err(format!("'{keyword}' is a reserved symbol"))
diff --git a/src/api/register.rs b/src/api/register.rs
index 43c43a72..8f4d4833 100644
--- a/src/api/register.rs
+++ b/src/api/register.rs
@@ -786,7 +786,7 @@ impl Engine {
         }
 
         #[cfg(not(feature = "no_module"))]
-        for (name, m) in self.global_sub_modules.as_deref().into_iter().flatten() {
+        for (name, m) in self.global_sub_modules.as_ref().into_iter().flatten() {
             signatures.extend(m.gen_fn_signatures().map(|f| format!("{name}::{f}")));
         }
 
diff --git a/src/ast/ast.rs b/src/ast/ast.rs
index 139f5634..6734a446 100644
--- a/src/ast/ast.rs
+++ b/src/ast/ast.rs
@@ -839,6 +839,8 @@ impl AST {
     ///
     ///     {                   // <- new block scope
     ///         const Z = 0;    // <- literal constant not at top-level
+    ///
+    ///         print(Z);       // make sure the block is not optimized away
     ///     }
     /// ")?;
     ///
diff --git a/src/ast/expr.rs b/src/ast/expr.rs
index 2f96af59..52d7ccd1 100644
--- a/src/ast/expr.rs
+++ b/src/ast/expr.rs
@@ -276,9 +276,9 @@ pub enum Expr {
     /// [String][ImmutableString] constant.
     StringConstant(ImmutableString, Position),
     /// An interpolated [string][ImmutableString].
-    InterpolatedString(Box<StaticVec<Expr>>, Position),
+    InterpolatedString(Box<FnArgsVec<Expr>>, Position),
     /// [ expr, ... ]
-    Array(Box<StaticVec<Expr>>, Position),
+    Array(Box<FnArgsVec<Expr>>, Position),
     /// #{ name:expr, ... }
     Map(
         Box<(StaticVec<(Ident, Expr)>, BTreeMap<Identifier, Dynamic>)>,
@@ -288,8 +288,8 @@ pub enum Expr {
     Unit(Position),
     /// Variable access - (optional long index, namespace, namespace hash, variable name), optional short index, position
     ///
-    /// The short index is [`u8`] which is used when the index is <= 255, which should be the vast
-    /// majority of cases (unless there are more than 255 variables defined!).
+    /// The short index is [`u8`] which is used when the index is <= 255, which should be
+    /// the vast majority of cases (unless there are more than 255 variables defined!).
     /// This is to avoid reading a pointer redirection during each variable access.
     Variable(
         Box<(Option<NonZeroUsize>, Namespace, u64, ImmutableString)>,
@@ -315,15 +315,15 @@ pub enum Expr {
     ///
     /// ### Flags
     ///
-    /// [`NEGATED`][ASTFlags::NEGATED] = `?.` (`.` if unset)
-    /// [`BREAK`][ASTFlags::BREAK] = terminate the chain (recurse into the chain if unset)
+    /// * [`NEGATED`][ASTFlags::NEGATED] = `?.` (`.` if unset)
+    /// * [`BREAK`][ASTFlags::BREAK] = terminate the chain (recurse into the chain if unset)
     Dot(Box<BinaryExpr>, ASTFlags, Position),
     /// lhs `[` rhs `]`
     ///
     /// ### Flags
     ///
-    /// [`NEGATED`][ASTFlags::NEGATED] = `?[` ... `]` (`[` ... `]` if unset)
-    /// [`BREAK`][ASTFlags::BREAK] = terminate the chain (recurse into the chain if unset)
+    /// * [`NEGATED`][ASTFlags::NEGATED] = `?[` ... `]` (`[` ... `]` if unset)
+    /// * [`BREAK`][ASTFlags::BREAK] = terminate the chain (recurse into the chain if unset)
     Index(Box<BinaryExpr>, ASTFlags, Position),
     /// lhs `&&` rhs
     And(Box<BinaryExpr>, Position),
diff --git a/src/ast/stmt.rs b/src/ast/stmt.rs
index 8487c4fb..65634092 100644
--- a/src/ast/stmt.rs
+++ b/src/ast/stmt.rs
@@ -663,7 +663,7 @@ pub enum Stmt {
     ///
     /// ### Flags
     ///
-    /// * [`NONE`][ASTFlags::NONE] = `while`
+    /// * [`NONE`][ASTFlags::NONE] = `while`  
     /// * [`NEGATED`][ASTFlags::NEGATED] = `until`
     Do(Box<FlowControl>, ASTFlags, Position),
     /// `for` `(` id `,` counter `)` `in` expr `{` stmt `}`
@@ -672,7 +672,7 @@ pub enum Stmt {
     ///
     /// ### Flags
     ///
-    /// * [`EXPORTED`][ASTFlags::EXPORTED] = `export`
+    /// * [`EXPORTED`][ASTFlags::EXPORTED] = `export`  
     /// * [`CONSTANT`][ASTFlags::CONSTANT] = `const`
     Var(Box<(Ident, Expr, Option<NonZeroUsize>)>, ASTFlags, Position),
     /// expr op`=` expr
diff --git a/src/restore.rs b/src/defer.rs
similarity index 59%
rename from src/restore.rs
rename to src/defer.rs
index d369f6bc..4bf0ff21 100644
--- a/src/restore.rs
+++ b/src/defer.rs
@@ -5,56 +5,56 @@ use std::ops::{Deref, DerefMut};
 use std::prelude::v1::*;
 
 /// Automatically restore state at the end of the scope.
-macro_rules! auto_restore {
+macro_rules! defer {
     (let $temp:ident = $var:ident . $prop:ident; $code:stmt) => {
-        auto_restore!(let $temp = $var.$prop; $code => move |v| v.$prop = $temp);
+        defer!(let $temp = $var.$prop; $code => move |v| v.$prop = $temp);
     };
     (let $temp:ident = $var:ident . $prop:ident; $code:stmt => $restore:expr) => {
         let $temp = $var.$prop;
         $code
-        auto_restore!($var => $restore);
+        defer!($var => $restore);
     };
     ($var:ident => $restore:ident; let $temp:ident = $save:expr;) => {
-        auto_restore!($var => $restore; let $temp = $save; {});
+        defer!($var => $restore; let $temp = $save; {});
     };
     ($var:ident if $guard:expr => $restore:ident; let $temp:ident = $save:expr;) => {
-        auto_restore!($var if $guard => $restore; let $temp = $save; {});
+        defer!($var if $guard => $restore; let $temp = $save; {});
     };
     ($var:ident => $restore:ident; let $temp:ident = $save:expr; $code:stmt) => {
         let $temp = $save;
         $code
-        auto_restore!($var => move |v| { v.$restore($temp); });
+        defer!($var => move |v| { v.$restore($temp); });
     };
     ($var:ident if $guard:expr => $restore:ident; let $temp:ident = $save:expr; $code:stmt) => {
         let $temp = $save;
         $code
-        auto_restore!($var if $guard => move |v| { v.$restore($temp); });
+        defer!($var if $guard => move |v| { v.$restore($temp); });
     };
     ($var:ident => $restore:expr) => {
-        auto_restore!($var = $var => $restore);
+        defer!($var = $var => $restore);
     };
     ($var:ident = $value:expr => $restore:expr) => {
-        let $var = &mut *crate::RestoreOnDrop::lock($value, $restore);
+        let $var = &mut *crate::Deferred::lock($value, $restore);
     };
     ($var:ident if Some($guard:ident) => $restore:expr) => {
-        auto_restore!($var = ($var) if Some($guard) => $restore);
+        defer!($var = ($var) if Some($guard) => $restore);
     };
     ($var:ident = ( $value:expr ) if Some($guard:ident) => $restore:expr) => {
         let mut __rx__;
         let $var = if let Some($guard) = $guard {
-            __rx__ = crate::RestoreOnDrop::lock($value, $restore);
+            __rx__ = crate::Deferred::lock($value, $restore);
             &mut *__rx__
         } else {
             &mut *$value
         };
     };
     ($var:ident if $guard:expr => $restore:expr) => {
-        auto_restore!($var = ($var) if $guard => $restore);
+        defer!($var = ($var) if $guard => $restore);
     };
     ($var:ident = ( $value:expr ) if $guard:expr => $restore:expr) => {
         let mut __rx__;
         let $var = if $guard {
-            __rx__ = crate::RestoreOnDrop::lock($value, $restore);
+            __rx__ = crate::Deferred::lock($value, $restore);
             &mut *__rx__
         } else {
             &mut *$value
@@ -64,13 +64,13 @@ macro_rules! auto_restore {
 
 /// Run custom restoration logic upon the end of scope.
 #[must_use]
-pub struct RestoreOnDrop<'a, T: ?Sized, R: FnOnce(&mut T)> {
-    value: &'a mut T,
-    restore: Option<R>,
+pub struct Deferred<'a, T: ?Sized, R: FnOnce(&mut T)> {
+    lock: &'a mut T,
+    defer: Option<R>,
 }
 
-impl<'a, T: ?Sized, R: FnOnce(&mut T)> RestoreOnDrop<'a, T, R> {
-    /// Create a new [`RestoreOnDrop`] that locks a mutable reference and runs restoration logic at
+impl<'a, T: ?Sized, R: FnOnce(&mut T)> Deferred<'a, T, R> {
+    /// Create a new [`Deferred`] that locks a mutable reference and runs restoration logic at
     /// the end of scope.
     ///
     /// Beware that the end of scope means the end of its lifetime, not necessarily waiting until
@@ -78,31 +78,31 @@ impl<'a, T: ?Sized, R: FnOnce(&mut T)> RestoreOnDrop<'a, T, R> {
     #[inline(always)]
     pub fn lock(value: &'a mut T, restore: R) -> Self {
         Self {
-            value,
-            restore: Some(restore),
+            lock: value,
+            defer: Some(restore),
         }
     }
 }
 
-impl<'a, T: ?Sized, R: FnOnce(&mut T)> Drop for RestoreOnDrop<'a, T, R> {
+impl<'a, T: ?Sized, R: FnOnce(&mut T)> Drop for Deferred<'a, T, R> {
     #[inline(always)]
     fn drop(&mut self) {
-        self.restore.take().unwrap()(self.value);
+        self.defer.take().unwrap()(self.lock);
     }
 }
 
-impl<'a, T: ?Sized, R: FnOnce(&mut T)> Deref for RestoreOnDrop<'a, T, R> {
+impl<'a, T: ?Sized, R: FnOnce(&mut T)> Deref for Deferred<'a, T, R> {
     type Target = T;
 
     #[inline(always)]
     fn deref(&self) -> &Self::Target {
-        self.value
+        self.lock
     }
 }
 
-impl<'a, T: ?Sized, R: FnOnce(&mut T)> DerefMut for RestoreOnDrop<'a, T, R> {
+impl<'a, T: ?Sized, R: FnOnce(&mut T)> DerefMut for Deferred<'a, T, R> {
     #[inline(always)]
     fn deref_mut(&mut self) -> &mut Self::Target {
-        self.value
+        self.lock
     }
 }
diff --git a/src/engine.rs b/src/engine.rs
index 1e35d21f..59516a82 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -96,8 +96,7 @@ pub struct Engine {
     pub(crate) global_modules: StaticVec<SharedModule>,
     /// A collection of all sub-modules directly loaded into the Engine.
     #[cfg(not(feature = "no_module"))]
-    pub(crate) global_sub_modules:
-        Option<Box<std::collections::BTreeMap<Identifier, SharedModule>>>,
+    pub(crate) global_sub_modules: Option<std::collections::BTreeMap<Identifier, SharedModule>>,
 
     /// A module resolution service.
     #[cfg(not(feature = "no_module"))]
@@ -107,15 +106,14 @@ pub struct Engine {
     pub(crate) interned_strings: Option<Box<Locked<StringsInterner>>>,
 
     /// A set of symbols to disable.
-    pub(crate) disabled_symbols: Option<Box<BTreeSet<Identifier>>>,
+    pub(crate) disabled_symbols: Option<BTreeSet<Identifier>>,
     /// A map containing custom keywords and precedence to recognize.
     #[cfg(not(feature = "no_custom_syntax"))]
-    pub(crate) custom_keywords:
-        Option<Box<std::collections::BTreeMap<Identifier, Option<Precedence>>>>,
+    pub(crate) custom_keywords: Option<std::collections::BTreeMap<Identifier, Option<Precedence>>>,
     /// Custom syntax.
     #[cfg(not(feature = "no_custom_syntax"))]
     pub(crate) custom_syntax: Option<
-        Box<std::collections::BTreeMap<Identifier, Box<crate::api::custom_syntax::CustomSyntax>>>,
+        std::collections::BTreeMap<Identifier, Box<crate::api::custom_syntax::CustomSyntax>>,
     >,
     /// Callback closure for filtering variable definition.
     pub(crate) def_var_filter: Option<Box<OnDefVarCallback>>,
diff --git a/src/eval/chaining.rs b/src/eval/chaining.rs
index a6184061..28dacaa9 100644
--- a/src/eval/chaining.rs
+++ b/src/eval/chaining.rs
@@ -67,7 +67,7 @@ impl Engine {
         idx: &mut Dynamic,
         pos: Position,
     ) -> RhaiResultOf<Dynamic> {
-        auto_restore! { let orig_level = global.level; global.level += 1 }
+        defer! { let orig_level = global.level; global.level += 1 }
 
         let hash = hash_idx().0;
         let args = &mut [target, idx];
@@ -88,7 +88,7 @@ impl Engine {
         is_ref_mut: bool,
         pos: Position,
     ) -> RhaiResultOf<(Dynamic, bool)> {
-        auto_restore! { let orig_level = global.level; global.level += 1 }
+        defer! { let orig_level = global.level; global.level += 1 }
 
         let hash = hash_idx().1;
         let args = &mut [target, idx, new_val];
@@ -344,8 +344,6 @@ impl Engine {
         expr: &Expr,
         new_val: Option<(Dynamic, &OpAssignment)>,
     ) -> RhaiResult {
-        let chain_type = ChainType::from(expr);
-
         let BinaryExpr { lhs, rhs } = match expr {
             #[cfg(not(feature = "no_index"))]
             Expr::Index(x, ..) => &**x,
@@ -356,27 +354,22 @@ impl Engine {
 
         let idx_values = &mut FnArgsVec::new_const();
 
-        match rhs {
+        match (rhs, ChainType::from(expr)) {
             // Short-circuit for simple property access: {expr}.prop
             #[cfg(not(feature = "no_object"))]
-            Expr::Property(..) if chain_type == ChainType::Dotting => (),
+            (Expr::Property(..), ChainType::Dotting) => (),
             #[cfg(not(feature = "no_object"))]
-            Expr::Property(..) => unreachable!("unexpected Expr::Property for indexing"),
-            // Short-circuit for simple method call: {expr}.func()
-            #[cfg(not(feature = "no_object"))]
-            Expr::FnCall(x, ..) if chain_type == ChainType::Dotting && x.args.is_empty() => (),
-            // Short-circuit for method call with all literal arguments: {expr}.func(1, 2, 3)
-            #[cfg(not(feature = "no_object"))]
-            Expr::FnCall(x, ..)
-                if chain_type == ChainType::Dotting && x.args.iter().all(Expr::is_constant) =>
-            {
-                idx_values.extend(x.args.iter().map(|expr| expr.get_literal_value().unwrap()))
+            (Expr::Property(..), ..) => {
+                unreachable!("unexpected Expr::Property for indexing")
             }
             // Short-circuit for indexing with literal: {expr}[1]
             #[cfg(not(feature = "no_index"))]
-            _ if chain_type == ChainType::Indexing && rhs.is_constant() => {
+            (_, ChainType::Indexing) if rhs.is_constant() => {
                 idx_values.push(rhs.get_literal_value().unwrap())
             }
+            // Short-circuit for simple method call: {expr}.func()
+            #[cfg(not(feature = "no_object"))]
+            (Expr::MethodCall(x, ..), ChainType::Dotting) if x.args.is_empty() => (),
             // All other patterns - evaluate the arguments chain
             _ => self.eval_dot_index_chain_arguments(
                 global,
@@ -394,12 +387,13 @@ impl Engine {
         #[cfg(not(feature = "debugging"))]
         let scope2 = ();
 
-        match lhs {
+        match (lhs, new_val) {
             // id.??? or id[???]
-            Expr::Variable(.., var_pos) => {
+            (Expr::Variable(.., var_pos), new_val) => {
+                self.track_operation(global, *var_pos)?;
+
                 #[cfg(feature = "debugging")]
                 self.run_debugger(global, caches, scope, this_ptr.as_deref_mut(), lhs)?;
-                self.track_operation(global, *var_pos)?;
 
                 let target = &mut self.search_namespace(global, caches, scope, this_ptr, lhs)?;
 
@@ -408,9 +402,9 @@ impl Engine {
                 )
             }
             // {expr}.??? = ??? or {expr}[???] = ???
-            _ if new_val.is_some() => unreachable!("cannot assign to an expression"),
+            (_, Some(..)) => unreachable!("cannot assign to an expression"),
             // {expr}.??? or {expr}[???]
-            lhs_expr => {
+            (lhs_expr, None) => {
                 let value = self
                     .eval_expr(global, caches, scope, this_ptr.as_deref_mut(), lhs_expr)?
                     .flatten();
@@ -418,7 +412,7 @@ impl Engine {
 
                 self.eval_dot_index_chain_raw(
                     global, caches, scope2, this_ptr, lhs_expr, expr, obj_ptr, rhs, idx_values,
-                    new_val,
+                    None,
                 )
             }
         }
@@ -438,27 +432,25 @@ impl Engine {
     ) -> RhaiResultOf<()> {
         self.track_operation(global, expr.position())?;
 
-        let chain_type = ChainType::from(parent);
-
-        match expr {
+        match (expr, ChainType::from(parent)) {
             #[cfg(not(feature = "no_object"))]
-            Expr::MethodCall(x, ..) if chain_type == ChainType::Dotting && !x.is_qualified() => {
+            (Expr::MethodCall(x, ..), ChainType::Dotting) => {
+                debug_assert!(
+                    !x.is_qualified(),
+                    "method call in dot chain should not be namespace-qualified"
+                );
+
                 for expr in &x.args {
                     let arg_value =
                         self.get_arg_value(global, caches, scope, this_ptr.as_deref_mut(), expr)?;
                     idx_values.push(arg_value.0.flatten());
                 }
             }
-            #[cfg(not(feature = "no_object"))]
-            Expr::MethodCall(..) if chain_type == ChainType::Dotting => {
-                unreachable!("function call in dot chain should not be namespace-qualified")
-            }
 
             #[cfg(not(feature = "no_object"))]
-            Expr::Property(..) if chain_type == ChainType::Dotting => (),
-            Expr::Property(..) => unreachable!("unexpected Expr::Property for indexing"),
+            (Expr::Property(..), ChainType::Dotting) => (),
 
-            Expr::Index(x, ..) | Expr::Dot(x, ..)
+            (Expr::Index(x, ..) | Expr::Dot(x, ..), chain_type)
                 if !parent.options().contains(ASTFlags::BREAK) =>
             {
                 let BinaryExpr { lhs, rhs, .. } = &**x;
@@ -466,37 +458,34 @@ impl Engine {
                 let mut _arg_values = FnArgsVec::new_const();
 
                 // Evaluate in left-to-right order
-                match lhs {
+                match (lhs, chain_type) {
                     #[cfg(not(feature = "no_object"))]
-                    Expr::Property(..) if chain_type == ChainType::Dotting => (),
-                    Expr::Property(..) => unreachable!("unexpected Expr::Property for indexing"),
+                    (Expr::Property(..), ChainType::Dotting) => (),
 
                     #[cfg(not(feature = "no_object"))]
-                    Expr::MethodCall(x, ..)
-                        if chain_type == ChainType::Dotting && !x.is_qualified() =>
-                    {
+                    (Expr::MethodCall(x, ..), ChainType::Dotting) => {
+                        debug_assert!(
+                            !x.is_qualified(),
+                            "method call in dot chain should not be namespace-qualified"
+                        );
+
                         for expr in &x.args {
                             let tp = this_ptr.as_deref_mut();
                             let arg_value = self.get_arg_value(global, caches, scope, tp, expr)?;
                             _arg_values.push(arg_value.0.flatten());
                         }
                     }
-                    #[cfg(not(feature = "no_object"))]
-                    Expr::MethodCall(..) if chain_type == ChainType::Dotting => {
-                        unreachable!("function call in dot chain should not be namespace-qualified")
-                    }
-                    #[cfg(not(feature = "no_object"))]
-                    expr if chain_type == ChainType::Dotting => {
-                        unreachable!("invalid dot expression: {:?}", expr);
-                    }
                     #[cfg(not(feature = "no_index"))]
-                    _ if chain_type == ChainType::Indexing => {
+                    (_, ChainType::Indexing) => {
                         _arg_values.push(
                             self.eval_expr(global, caches, scope, this_ptr.as_deref_mut(), lhs)?
                                 .flatten(),
                         );
                     }
-                    expr => unreachable!("unknown chained expression: {:?}", expr),
+                    #[allow(unreachable_patterns)]
+                    (expr, chain_type) => {
+                        unreachable!("unknown {:?} expression: {:?}", chain_type, expr)
+                    }
                 }
 
                 // Push in reverse order
@@ -507,16 +496,13 @@ impl Engine {
                 idx_values.extend(_arg_values);
             }
 
-            #[cfg(not(feature = "no_object"))]
-            _ if chain_type == ChainType::Dotting => {
-                unreachable!("invalid dot expression: {:?}", expr);
-            }
             #[cfg(not(feature = "no_index"))]
-            _ if chain_type == ChainType::Indexing => idx_values.push(
+            (_, ChainType::Indexing) => idx_values.push(
                 self.eval_expr(global, caches, scope, this_ptr, expr)?
                     .flatten(),
             ),
-            _ => unreachable!("unknown chained expression: {:?}", expr),
+            #[allow(unreachable_patterns)]
+            (expr, chain_type) => unreachable!("unknown {:?} expression: {:?}", chain_type, expr),
         }
 
         Ok(())
@@ -554,9 +540,9 @@ impl Engine {
 
                 let pos = rhs.start_position();
 
-                match rhs {
+                match (rhs, new_val) {
                     // xxx[idx].expr... | xxx[idx][expr]...
-                    Expr::Dot(x, ..) | Expr::Index(x, ..)
+                    (Expr::Dot(x, ..) | Expr::Index(x, ..), new_val)
                         if !parent.options().contains(ASTFlags::BREAK) =>
                     {
                         #[cfg(feature = "debugging")]
@@ -603,11 +589,10 @@ impl Engine {
                         Ok(result)
                     }
                     // xxx[rhs] op= new_val
-                    _ if new_val.is_some() => {
+                    (_, Some((new_val, op_info))) => {
                         #[cfg(feature = "debugging")]
                         self.run_debugger(global, caches, scope, this_ptr, parent)?;
 
-                        let (new_val, op_info) = new_val.expect("`Some`");
                         let idx_val = &mut idx_values.pop().unwrap();
                         let idx = &mut idx_val.clone();
 
@@ -660,7 +645,7 @@ impl Engine {
                         Ok((Dynamic::UNIT, true))
                     }
                     // xxx[rhs]
-                    _ => {
+                    (_, None) => {
                         #[cfg(feature = "debugging")]
                         self.run_debugger(global, caches, scope, this_ptr, parent)?;
 
@@ -681,21 +666,30 @@ impl Engine {
                     return Ok((Dynamic::UNIT, false));
                 }
 
-                match rhs {
+                match (rhs, new_val, target.is_map()) {
+                    // xxx.fn_name(...) = ???
+                    (Expr::MethodCall(..), Some(..), ..) => {
+                        unreachable!("method call cannot be assigned to")
+                    }
                     // xxx.fn_name(arg_expr_list)
-                    Expr::MethodCall(x, pos) if !x.is_qualified() && new_val.is_none() => {
+                    (Expr::MethodCall(x, pos), None, ..) => {
+                        debug_assert!(
+                            !x.is_qualified(),
+                            "method call in dot chain should not be namespace-qualified"
+                        );
+
                         #[cfg(feature = "debugging")]
                         let reset =
                             self.run_debugger_with_reset(global, caches, scope, this_ptr, rhs)?;
                         #[cfg(feature = "debugging")]
-                        auto_restore! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
+                        defer! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
 
                         let crate::ast::FnCallExpr {
                             name, hashes, args, ..
                         } = &**x;
 
                         // Truncate the index values upon exit
-                        auto_restore! { idx_values => truncate; let offset = idx_values.len() - args.len(); }
+                        defer! { idx_values => truncate; let offset = idx_values.len() - args.len(); }
 
                         let call_args = &mut idx_values[offset..];
                         let arg1_pos = args.get(0).map_or(Position::NONE, Expr::position);
@@ -704,21 +698,12 @@ impl Engine {
                             global, caches, name, *hashes, target, call_args, arg1_pos, *pos,
                         )
                     }
-                    // xxx.fn_name(...) = ???
-                    Expr::MethodCall(..) if new_val.is_some() => {
-                        unreachable!("method call cannot be assigned to")
-                    }
-                    // xxx.module::fn_name(...) - syntax error
-                    Expr::MethodCall(..) => {
-                        unreachable!("function call in dot chain should not be namespace-qualified")
-                    }
                     // {xxx:map}.id op= ???
-                    Expr::Property(x, pos) if new_val.is_some() && target.is_map() => {
+                    (Expr::Property(x, pos), Some((new_val, op_info)), true) => {
                         #[cfg(feature = "debugging")]
                         self.run_debugger(global, caches, scope, this_ptr, rhs)?;
 
                         let index = &mut x.2.clone().into();
-                        let (new_val, op_info) = new_val.expect("`Some`");
                         {
                             let val_target = &mut self.get_indexed_mut(
                                 global, caches, target, index, *pos, op_pos, true, false,
@@ -731,7 +716,7 @@ impl Engine {
                         Ok((Dynamic::UNIT, true))
                     }
                     // {xxx:map}.id
-                    Expr::Property(x, pos) if target.is_map() => {
+                    (Expr::Property(x, pos), None, true) => {
                         #[cfg(feature = "debugging")]
                         self.run_debugger(global, caches, scope, this_ptr, rhs)?;
 
@@ -742,12 +727,11 @@ impl Engine {
                         Ok((val.take_or_clone(), false))
                     }
                     // xxx.id op= ???
-                    Expr::Property(x, pos) if new_val.is_some() => {
+                    (Expr::Property(x, pos), Some((mut new_val, op_info)), false) => {
                         #[cfg(feature = "debugging")]
                         self.run_debugger(global, caches, scope, this_ptr, rhs)?;
 
                         let ((getter, hash_get), (setter, hash_set), name) = &**x;
-                        let (mut new_val, op_info) = new_val.expect("`Some`");
 
                         if op_info.is_op_assignment() {
                             let args = &mut [target.as_mut()];
@@ -807,7 +791,7 @@ impl Engine {
                         })
                     }
                     // xxx.id
-                    Expr::Property(x, pos) => {
+                    (Expr::Property(x, pos), None, false) => {
                         #[cfg(feature = "debugging")]
                         self.run_debugger(global, caches, scope, this_ptr, rhs)?;
 
@@ -836,7 +820,7 @@ impl Engine {
                         )
                     }
                     // {xxx:map}.sub_lhs[expr] | {xxx:map}.sub_lhs.expr
-                    Expr::Index(x, ..) | Expr::Dot(x, ..) if target.is_map() => {
+                    (Expr::Index(x, ..) | Expr::Dot(x, ..), new_val, true) => {
                         let _node = &x.lhs;
                         let mut _this_ptr = this_ptr;
                         let _tp = _this_ptr.as_deref_mut();
@@ -852,19 +836,24 @@ impl Engine {
                                 )?
                             }
                             // {xxx:map}.fn_name(arg_expr_list)[expr] | {xxx:map}.fn_name(arg_expr_list).expr
-                            Expr::MethodCall(ref x, pos) if !x.is_qualified() => {
+                            Expr::MethodCall(ref x, pos) => {
+                                debug_assert!(
+                                    !x.is_qualified(),
+                                    "method call in dot chain should not be namespace-qualified"
+                                );
+
                                 #[cfg(feature = "debugging")]
                                 let reset = self
                                     .run_debugger_with_reset(global, caches, scope, _tp, _node)?;
                                 #[cfg(feature = "debugging")]
-                                auto_restore! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
+                                defer! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
 
                                 let crate::ast::FnCallExpr {
                                     name, hashes, args, ..
                                 } = &**x;
 
                                 // Truncate the index values upon exit
-                                auto_restore! { idx_values => truncate; let offset = idx_values.len() - args.len(); }
+                                defer! { idx_values => truncate; let offset = idx_values.len() - args.len(); }
 
                                 let call_args = &mut idx_values[offset..];
                                 let arg1_pos = args.get(0).map_or(Position::NONE, Expr::position);
@@ -875,10 +864,6 @@ impl Engine {
                                 .0
                                 .into()
                             }
-                            // {xxx:map}.module::fn_name(...) - syntax error
-                            Expr::MethodCall(..) => unreachable!(
-                                "function call in dot chain should not be namespace-qualified"
-                            ),
                             // Others - syntax error
                             ref expr => unreachable!("invalid dot expression: {:?}", expr),
                         };
@@ -889,7 +874,7 @@ impl Engine {
                         )
                     }
                     // xxx.sub_lhs[expr] | xxx.sub_lhs.expr
-                    Expr::Index(x, ..) | Expr::Dot(x, ..) => {
+                    (Expr::Index(x, ..) | Expr::Dot(x, ..), new_val, ..) => {
                         let _node = &x.lhs;
                         let mut _this_ptr = this_ptr;
                         let _tp = _this_ptr.as_deref_mut();
@@ -970,21 +955,26 @@ impl Engine {
                                 Ok((result, may_be_changed))
                             }
                             // xxx.fn_name(arg_expr_list)[expr] | xxx.fn_name(arg_expr_list).expr
-                            Expr::MethodCall(ref f, pos) if !f.is_qualified() => {
+                            Expr::MethodCall(ref f, pos) => {
+                                debug_assert!(
+                                    !f.is_qualified(),
+                                    "method call in dot chain should not be namespace-qualified"
+                                );
+
                                 let val = {
                                     #[cfg(feature = "debugging")]
                                     let reset = self.run_debugger_with_reset(
                                         global, caches, scope, _tp, _node,
                                     )?;
                                     #[cfg(feature = "debugging")]
-                                    auto_restore! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
+                                    defer! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
 
                                     let crate::ast::FnCallExpr {
                                         name, hashes, args, ..
                                     } = &**f;
 
                                     // Truncate the index values upon exit
-                                    auto_restore! { idx_values => truncate; let offset = idx_values.len() - args.len(); }
+                                    defer! { idx_values => truncate; let offset = idx_values.len() - args.len(); }
 
                                     let call_args = &mut idx_values[offset..];
                                     let pos1 = args.get(0).map_or(Position::NONE, Expr::position);
@@ -1002,16 +992,12 @@ impl Engine {
                                     idx_values, new_val,
                                 )
                             }
-                            // xxx.module::fn_name(...) - syntax error
-                            Expr::MethodCall(..) => unreachable!(
-                                "function call in dot chain should not be namespace-qualified"
-                            ),
                             // Others - syntax error
                             ref expr => unreachable!("invalid dot expression: {:?}", expr),
                         }
                     }
                     // Syntax error
-                    expr => unreachable!("invalid chaining expression: {:?}", expr),
+                    (expr, ..) => unreachable!("invalid chaining expression: {:?}", expr),
                 }
             }
         }
diff --git a/src/eval/expr.rs b/src/eval/expr.rs
index 540eb7a7..f1555a3d 100644
--- a/src/eval/expr.rs
+++ b/src/eval/expr.rs
@@ -236,16 +236,13 @@ impl Engine {
         mut this_ptr: Option<&mut Dynamic>,
         expr: &Expr,
     ) -> RhaiResult {
-        // Coded this way for better branch prediction.
-        // Popular branches are lifted out of the `match` statement into their own branches.
+        self.track_operation(global, expr.position())?;
 
         #[cfg(feature = "debugging")]
         let reset =
             self.run_debugger_with_reset(global, caches, scope, this_ptr.as_deref_mut(), expr)?;
         #[cfg(feature = "debugging")]
-        auto_restore! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
-
-        self.track_operation(global, expr.position())?;
+        defer! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
 
         match expr {
             // Constants
@@ -262,17 +259,18 @@ impl Engine {
                 self.eval_fn_call_expr(global, caches, scope, this_ptr, x, *pos)
             }
 
-            Expr::Variable(x, index, var_pos) => {
-                if index.is_none() && x.0.is_none() && x.3 == KEYWORD_THIS {
-                    this_ptr
-                        .ok_or_else(|| ERR::ErrorUnboundThis(*var_pos).into())
-                        .cloned()
-                } else {
-                    self.search_namespace(global, caches, scope, this_ptr, expr)
-                        .map(Target::take_or_clone)
-                }
+            Expr::Variable(x, index, var_pos)
+                if index.is_none() && x.0.is_none() && x.3 == KEYWORD_THIS =>
+            {
+                this_ptr
+                    .ok_or_else(|| ERR::ErrorUnboundThis(*var_pos).into())
+                    .cloned()
             }
 
+            Expr::Variable(..) => self
+                .search_namespace(global, caches, scope, this_ptr, expr)
+                .map(Target::take_or_clone),
+
             Expr::InterpolatedString(x, _) => {
                 let mut concat = SmartString::new_const();
 
diff --git a/src/eval/stmt.rs b/src/eval/stmt.rs
index 2410d036..5d090b76 100644
--- a/src/eval/stmt.rs
+++ b/src/eval/stmt.rs
@@ -43,7 +43,7 @@ impl Engine {
         }
 
         // Restore scope at end of block if necessary
-        auto_restore! { scope if restore_orig_state => rewind; let orig_scope_len = scope.len(); }
+        defer! { scope if restore_orig_state => rewind; let orig_scope_len = scope.len(); }
 
         // Restore global state at end of block if necessary
         let orig_always_search_scope = global.always_search_scope;
@@ -54,7 +54,7 @@ impl Engine {
             global.scope_level += 1;
         }
 
-        auto_restore! { global if restore_orig_state => move |g| {
+        defer! { global if restore_orig_state => move |g| {
             g.scope_level -= 1;
 
             #[cfg(not(feature = "no_module"))]
@@ -66,7 +66,7 @@ impl Engine {
         }}
 
         // Pop new function resolution caches at end of block
-        auto_restore! {
+        defer! {
             caches => rewind_fn_resolution_caches;
             let orig_fn_resolution_caches_len = caches.fn_resolution_caches_len();
         }
@@ -209,7 +209,7 @@ impl Engine {
                         get_builtin_op_assignment_fn(op_x, &*lock_guard, &new_val)
                     {
                         // We may not need to bump the level because built-in's do not need it.
-                        //auto_restore! { let orig_level = global.level; global.level += 1 }
+                        //defer! { let orig_level = global.level; global.level += 1 }
 
                         let args = &mut [&mut *lock_guard, &mut new_val];
                         let context = need_context
@@ -267,13 +267,13 @@ impl Engine {
         stmt: &Stmt,
         rewind_scope: bool,
     ) -> RhaiResult {
+        self.track_operation(global, stmt.position())?;
+
         #[cfg(feature = "debugging")]
         let reset =
             self.run_debugger_with_reset(global, caches, scope, this_ptr.as_deref_mut(), stmt)?;
         #[cfg(feature = "debugging")]
-        auto_restore! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
-
-        self.track_operation(global, stmt.position())?;
+        defer! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
 
         match stmt {
             // No-op
@@ -307,6 +307,8 @@ impl Engine {
                         .eval_expr(global, caches, scope, this_ptr.as_deref_mut(), rhs)?
                         .flatten();
 
+                    self.track_operation(global, lhs.position())?;
+
                     let mut target = self.search_namespace(global, caches, scope, this_ptr, lhs)?;
 
                     let is_temp_result = !target.is_ref();
@@ -326,8 +328,6 @@ impl Engine {
                         .into());
                     }
 
-                    self.track_operation(global, lhs.position())?;
-
                     self.eval_op_assignment(global, caches, op_info, lhs, &mut target, rhs_val)?;
                 } else {
                     #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
@@ -664,7 +664,7 @@ impl Engine {
                     .or_else(|| global.get_iter(iter_type))
                     .or_else(|| {
                         self.global_sub_modules
-                            .as_deref()
+                            .as_ref()
                             .into_iter()
                             .flatten()
                             .find_map(|(_, m)| m.get_qualified_iter(iter_type))
@@ -673,7 +673,7 @@ impl Engine {
                 let iter_func = iter_func.ok_or_else(|| ERR::ErrorFor(expr.start_position()))?;
 
                 // Restore scope at end of statement
-                auto_restore! { scope => rewind; let orig_scope_len = scope.len(); }
+                defer! { scope => rewind; let orig_scope_len = scope.len(); }
 
                 // Add the loop variables
                 let counter_index = (!counter.is_empty()).then(|| {
@@ -686,53 +686,53 @@ impl Engine {
 
                 let mut result = Dynamic::UNIT;
 
-                for (x, iter_value) in iter_func(iter_obj).enumerate() {
-                    // Increment counter
-                    if let Some(counter_index) = counter_index {
-                        // As the variable increments from 0, this should always work
-                        // since any overflow will first be caught below.
-                        let index_value = x as INT;
+                if body.is_empty() {
+                    for _ in iter_func(iter_obj) {
+                        self.track_operation(global, body.position())?;
+                    }
+                } else {
+                    for (x, iter_value) in iter_func(iter_obj).enumerate() {
+                        // Increment counter
+                        if let Some(counter_index) = counter_index {
+                            // As the variable increments from 0, this should always work
+                            // since any overflow will first be caught below.
+                            let index_value = x as INT;
 
-                        #[cfg(not(feature = "unchecked"))]
-                        #[allow(clippy::absurd_extreme_comparisons)]
-                        if index_value > crate::MAX_USIZE_INT {
-                            return Err(ERR::ErrorArithmetic(
-                                format!("for-loop counter overflow: {x}"),
-                                counter.pos,
-                            )
-                            .into());
+                            #[cfg(not(feature = "unchecked"))]
+                            #[allow(clippy::absurd_extreme_comparisons)]
+                            if index_value > crate::MAX_USIZE_INT {
+                                return Err(ERR::ErrorArithmetic(
+                                    format!("for-loop counter overflow: {x}"),
+                                    counter.pos,
+                                )
+                                .into());
+                            }
+
+                            *scope.get_mut_by_index(counter_index).write_lock().unwrap() =
+                                Dynamic::from_int(index_value);
                         }
 
-                        *scope.get_mut_by_index(counter_index).write_lock().unwrap() =
-                            Dynamic::from_int(index_value);
-                    }
+                        // Set loop value
+                        let value = iter_value
+                            .map_err(|err| err.fill_position(expr.position()))?
+                            .flatten();
 
-                    // Set loop value
-                    let value = iter_value
-                        .map_err(|err| err.fill_position(expr.position()))?
-                        .flatten();
+                        *scope.get_mut_by_index(index).write_lock().unwrap() = value;
 
-                    *scope.get_mut_by_index(index).write_lock().unwrap() = value;
+                        // Run block
+                        let this_ptr = this_ptr.as_deref_mut();
 
-                    // Run block
-                    self.track_operation(global, body.position())?;
-
-                    if body.is_empty() {
-                        continue;
-                    }
-
-                    let this_ptr = this_ptr.as_deref_mut();
-
-                    match self.eval_stmt_block(global, caches, scope, this_ptr, body, true) {
-                        Ok(_) => (),
-                        Err(err) => match *err {
-                            ERR::LoopBreak(false, ..) => (),
-                            ERR::LoopBreak(true, value, ..) => {
-                                result = value;
-                                break;
-                            }
-                            _ => return Err(err),
-                        },
+                        match self.eval_stmt_block(global, caches, scope, this_ptr, body, true) {
+                            Ok(_) => (),
+                            Err(err) => match *err {
+                                ERR::LoopBreak(false, ..) => (),
+                                ERR::LoopBreak(true, value, ..) => {
+                                    result = value;
+                                    break;
+                                }
+                                _ => return Err(err),
+                            },
+                        }
                     }
                 }
 
@@ -808,7 +808,7 @@ impl Engine {
                         };
 
                         // Restore scope at end of block
-                        auto_restore! { scope if !catch_var.is_unit() => rewind; let orig_scope_len = scope.len(); }
+                        defer! { scope if !catch_var.is_unit() => rewind; let orig_scope_len = scope.len(); }
 
                         if let Expr::Variable(x, ..) = catch_var {
                             scope.push(x.3.clone(), err_value);
diff --git a/src/func/call.rs b/src/func/call.rs
index e5fa0507..dac38df3 100644
--- a/src/func/call.rs
+++ b/src/func/call.rs
@@ -206,7 +206,7 @@ impl Engine {
                         .or_else(|| _global.get_qualified_fn(hash, true))
                         .or_else(|| {
                             self.global_sub_modules
-                                .as_deref()
+                                .as_ref()
                                 .into_iter()
                                 .flatten()
                                 .filter(|(_, m)| m.contains_indexed_global_functions())
@@ -248,7 +248,7 @@ impl Engine {
                         #[cfg(not(feature = "no_module"))]
                         let is_dynamic = is_dynamic
                             || _global.may_contain_dynamic_fn(hash_base)
-                            || self.global_sub_modules.as_deref().map_or(false, |m| {
+                            || self.global_sub_modules.as_ref().map_or(false, |m| {
                                 m.values().any(|m| m.may_contain_dynamic_fn(hash_base))
                             });
 
@@ -488,7 +488,7 @@ impl Engine {
             // index getter function not found?
             #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
             crate::engine::FN_IDX_GET => {
-                assert!(args.len() == 2);
+                debug_assert_eq!(args.len(), 2);
 
                 let t0 = self.map_type_name(args[0].type_name());
                 let t1 = self.map_type_name(args[1].type_name());
@@ -499,7 +499,7 @@ impl Engine {
             // index setter function not found?
             #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
             crate::engine::FN_IDX_SET => {
-                assert!(args.len() == 3);
+                debug_assert_eq!(args.len(), 3);
 
                 let t0 = self.map_type_name(args[0].type_name());
                 let t1 = self.map_type_name(args[1].type_name());
@@ -511,7 +511,7 @@ impl Engine {
             // Getter function not found?
             #[cfg(not(feature = "no_object"))]
             _ if name.starts_with(crate::engine::FN_GET) => {
-                assert!(args.len() == 1);
+                debug_assert_eq!(args.len(), 1);
 
                 let prop = &name[crate::engine::FN_GET.len()..];
                 let t0 = self.map_type_name(args[0].type_name());
@@ -528,7 +528,7 @@ impl Engine {
             // Setter function not found?
             #[cfg(not(feature = "no_object"))]
             _ if name.starts_with(crate::engine::FN_SET) => {
-                assert!(args.len() == 2);
+                debug_assert_eq!(args.len(), 2);
 
                 let prop = &name[crate::engine::FN_SET.len()..];
                 let t0 = self.map_type_name(args[0].type_name());
@@ -573,57 +573,46 @@ impl Engine {
         _is_method_call: bool,
         pos: Position,
     ) -> RhaiResultOf<(Dynamic, bool)> {
+        // These may be redirected from method style calls.
+        if hashes.is_native_only() {
+            let error = match fn_name {
+                // Handle type_of()
+                KEYWORD_TYPE_OF => {
+                    if args.len() == 1 {
+                        let typ = self.get_interned_string(self.map_type_name(args[0].type_name()));
+                        return Ok((typ.into(), false));
+                    }
+                    true
+                }
+
+                #[cfg(not(feature = "no_closure"))]
+                crate::engine::KEYWORD_IS_SHARED => {
+                    if args.len() == 1 {
+                        return Ok((args[0].is_shared().into(), false));
+                    }
+                    true
+                }
+
+                #[cfg(not(feature = "no_function"))]
+                crate::engine::KEYWORD_IS_DEF_FN => true,
+
+                KEYWORD_FN_PTR | KEYWORD_EVAL | KEYWORD_IS_DEF_VAR | KEYWORD_FN_PTR_CALL
+                | KEYWORD_FN_PTR_CURRY => true,
+
+                _ => false,
+            };
+
+            if error {
+                let sig = self.gen_fn_call_signature(fn_name, args);
+                return Err(ERR::ErrorFunctionNotFound(sig, pos).into());
+            }
+        }
+
         // Check for data race.
         #[cfg(not(feature = "no_closure"))]
         ensure_no_data_race(fn_name, args, is_ref_mut)?;
 
-        auto_restore! { let orig_level = global.level; global.level += 1 }
-
-        // These may be redirected from method style calls.
-        if hashes.is_native_only() {
-            match fn_name {
-                // Handle type_of()
-                KEYWORD_TYPE_OF if args.len() == 1 => {
-                    let typ = self.get_interned_string(self.map_type_name(args[0].type_name()));
-                    return Ok((typ.into(), false));
-                }
-
-                // Handle is_def_fn()
-                #[cfg(not(feature = "no_function"))]
-                crate::engine::KEYWORD_IS_DEF_FN
-                    if args.len() == 2 && args[0].is_fnptr() && args[1].is_int() =>
-                {
-                    let fn_name = args[0].read_lock::<ImmutableString>().expect("`FnPtr`");
-                    let num_params = args[1].as_int().expect("`INT`");
-
-                    return Ok((
-                        if (0..=crate::MAX_USIZE_INT).contains(&num_params) {
-                            #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)]
-                            let hash_script =
-                                calc_fn_hash(None, fn_name.as_str(), num_params as usize);
-                            self.has_script_fn(global, caches, hash_script)
-                        } else {
-                            false
-                        }
-                        .into(),
-                        false,
-                    ));
-                }
-
-                // Handle is_shared()
-                #[cfg(not(feature = "no_closure"))]
-                crate::engine::KEYWORD_IS_SHARED => {
-                    unreachable!("{} called as method", fn_name)
-                }
-
-                KEYWORD_FN_PTR | KEYWORD_EVAL | KEYWORD_IS_DEF_VAR | KEYWORD_FN_PTR_CALL
-                | KEYWORD_FN_PTR_CURRY => {
-                    unreachable!("{} called as method", fn_name)
-                }
-
-                _ => (),
-            }
-        }
+        defer! { let orig_level = global.level; global.level += 1 }
 
         // Script-defined function call?
         #[cfg(not(feature = "no_function"))]
@@ -668,7 +657,7 @@ impl Engine {
                 };
 
                 let orig_source = mem::replace(&mut global.source, source.clone());
-                auto_restore! { global => move |g| g.source = orig_source }
+                defer! { global => move |g| g.source = orig_source }
 
                 return if _is_method_call {
                     // Method call of script function - map first argument to `this`
@@ -696,7 +685,7 @@ impl Engine {
                         backup.change_first_arg_to_copy(args);
                     }
 
-                    auto_restore! { args = (args) if swap => move |a| backup.restore_first_arg(a) }
+                    defer! { args = (args) if swap => move |a| backup.restore_first_arg(a) }
 
                     self.call_script_fn(global, caches, scope, None, environ, f, args, true, pos)
                 }
@@ -740,7 +729,7 @@ impl Engine {
             })
         });
         #[cfg(feature = "debugging")]
-        auto_restore! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
+        defer! { global if Some(reset) => move |g| g.debugger_mut().reset_status(reset) }
 
         self.eval_expr(global, caches, scope, this_ptr, arg_expr)
             .map(|r| (r, arg_expr.start_position()))
@@ -1110,7 +1099,7 @@ impl Engine {
                     FnCallHashes::from_hash(calc_fn_hash(None, name, args_len))
                 };
             }
-            // Handle Fn()
+            // Handle Fn(fn_name)
             KEYWORD_FN_PTR if total_args == 1 => {
                 let arg = first_arg.unwrap();
                 let (arg_value, arg_pos) =
@@ -1125,7 +1114,7 @@ impl Engine {
                     .map_err(|err| err.fill_position(arg_pos));
             }
 
-            // Handle curry()
+            // Handle curry(x, ...)
             KEYWORD_FN_PTR_CURRY if total_args > 1 => {
                 let first = first_arg.unwrap();
                 let (arg_value, arg_pos) =
@@ -1148,7 +1137,7 @@ impl Engine {
                 return Ok(fn_ptr.into());
             }
 
-            // Handle is_shared()
+            // Handle is_shared(var)
             #[cfg(not(feature = "no_closure"))]
             crate::engine::KEYWORD_IS_SHARED if total_args == 1 => {
                 let arg = first_arg.unwrap();
@@ -1157,7 +1146,7 @@ impl Engine {
                 return Ok(arg_value.is_shared().into());
             }
 
-            // Handle is_def_fn()
+            // Handle is_def_fn(fn_name, arity)
             #[cfg(not(feature = "no_function"))]
             crate::engine::KEYWORD_IS_DEF_FN if total_args == 2 => {
                 let first = first_arg.unwrap();
@@ -1175,17 +1164,54 @@ impl Engine {
                     .as_int()
                     .map_err(|typ| self.make_type_mismatch_err::<crate::INT>(typ, arg_pos))?;
 
-                return Ok(if (0..=crate::MAX_USIZE_INT).contains(&num_params) {
+                return Ok(if num_params >= 0 {
                     #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)]
                     let hash_script = calc_fn_hash(None, &fn_name, num_params as usize);
-                    self.has_script_fn(global, caches, hash_script)
+                    self.has_script_fn(global, caches, hash_script).into()
                 } else {
-                    false
-                }
-                .into());
+                    Dynamic::FALSE
+                });
             }
 
-            // Handle is_def_var()
+            // Handle is_def_fn(this_type, fn_name, arity)
+            #[cfg(not(feature = "no_function"))]
+            #[cfg(not(feature = "no_object"))]
+            crate::engine::KEYWORD_IS_DEF_FN if total_args == 3 => {
+                let first = first_arg.unwrap();
+                let (arg_value, arg_pos) =
+                    self.get_arg_value(global, caches, scope, this_ptr.as_deref_mut(), first)?;
+
+                let this_type = arg_value
+                    .into_immutable_string()
+                    .map_err(|typ| self.make_type_mismatch_err::<ImmutableString>(typ, arg_pos))?;
+
+                let (arg_value, arg_pos) =
+                    self.get_arg_value(global, caches, scope, this_ptr.as_deref_mut(), &a_expr[0])?;
+
+                let fn_name = arg_value
+                    .into_immutable_string()
+                    .map_err(|typ| self.make_type_mismatch_err::<ImmutableString>(typ, arg_pos))?;
+
+                let (arg_value, arg_pos) =
+                    self.get_arg_value(global, caches, scope, this_ptr, &a_expr[1])?;
+
+                let num_params = arg_value
+                    .as_int()
+                    .map_err(|typ| self.make_type_mismatch_err::<crate::INT>(typ, arg_pos))?;
+
+                return Ok(if num_params >= 0 {
+                    #[allow(clippy::cast_sign_loss, clippy::cast_possible_truncation)]
+                    let hash_script = crate::calc_typed_method_hash(
+                        calc_fn_hash(None, &fn_name, num_params as usize),
+                        &this_type,
+                    );
+                    self.has_script_fn(global, caches, hash_script).into()
+                } else {
+                    Dynamic::FALSE
+                });
+            }
+
+            // Handle is_def_var(fn_name)
             KEYWORD_IS_DEF_VAR if total_args == 1 => {
                 let arg = first_arg.unwrap();
                 let (arg_value, arg_pos) =
@@ -1196,7 +1222,7 @@ impl Engine {
                 return Ok(scope.contains(&var_name).into());
             }
 
-            // Handle eval()
+            // Handle eval(script)
             KEYWORD_EVAL if total_args == 1 => {
                 // eval - only in function call style
                 let orig_scope_len = scope.len();
@@ -1365,10 +1391,11 @@ impl Engine {
 
                 // Get target reference to first argument
                 let first_arg = &args_expr[0];
-                let target = self.search_scope_only(global, caches, scope, this_ptr, first_arg)?;
 
                 self.track_operation(global, first_arg.position())?;
 
+                let target = self.search_scope_only(global, caches, scope, this_ptr, first_arg)?;
+
                 #[cfg(not(feature = "no_closure"))]
                 let target_is_shared = target.is_shared();
                 #[cfg(feature = "no_closure")]
@@ -1433,8 +1460,6 @@ impl Engine {
                     }),
                 );
 
-                self.track_operation(global, pos)?;
-
                 if let Some(f) = module.get_qualified_fn(hash_qualified_fn) {
                     func = Some(f);
                     break;
@@ -1452,7 +1477,7 @@ impl Engine {
             }
         }
 
-        auto_restore! { let orig_level = global.level; global.level += 1 }
+        defer! { let orig_level = global.level; global.level += 1 }
 
         match func {
             #[cfg(not(feature = "no_function"))]
@@ -1463,7 +1488,7 @@ impl Engine {
                 let scope = &mut Scope::new();
 
                 let orig_source = mem::replace(&mut global.source, module.id_raw().cloned());
-                auto_restore! { global => move |g| g.source = orig_source }
+                defer! { global => move |g| g.source = orig_source }
 
                 self.call_script_fn(global, caches, scope, None, environ, f, args, true, pos)
             }
@@ -1730,7 +1755,7 @@ impl Engine {
                 get_builtin_binary_op_fn(op_token.as_ref().unwrap(), operands[0], operands[1])
             {
                 // We may not need to bump the level because built-in's do not need it.
-                //auto_restore! { let orig_level = global.level; global.level += 1 }
+                //defer! { let orig_level = global.level; global.level += 1 }
 
                 let context =
                     need_context.then(|| (self, name.as_str(), None, &*global, pos).into());
diff --git a/src/func/script.rs b/src/func/script.rs
index 4d119cfc..98551fe5 100644
--- a/src/func/script.rs
+++ b/src/func/script.rs
@@ -35,7 +35,7 @@ impl Engine {
         rewind_scope: bool,
         pos: Position,
     ) -> RhaiResult {
-        assert_eq!(fn_def.params.len(), args.len());
+        debug_assert_eq!(fn_def.params.len(), args.len());
 
         self.track_operation(global, pos)?;
 
@@ -219,7 +219,7 @@ impl Engine {
             // Then check imported modules
             global.contains_qualified_fn(hash_script)
             // Then check sub-modules
-            || self.global_sub_modules.as_deref().map_or(false, |m| {
+            || self.global_sub_modules.as_ref().map_or(false, |m| {
                 m.values().any(|m| m.contains_qualified_fn(hash_script))
             });
 
diff --git a/src/lib.rs b/src/lib.rs
index 8f4dda89..63b342ec 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -102,7 +102,7 @@ use std::prelude::v1::*;
 #[macro_use]
 mod reify;
 #[macro_use]
-mod restore;
+mod defer;
 
 mod api;
 mod ast;
@@ -225,6 +225,7 @@ pub use api::custom_syntax::Expression;
 pub use api::files::{eval_file, run_file};
 pub use api::{eval::eval, events::VarDefInfo, run::run};
 pub use ast::{FnAccess, AST};
+use defer::Deferred;
 pub use engine::{Engine, OP_CONTAINS, OP_EQUALS};
 pub use eval::EvalContext;
 #[cfg(not(feature = "no_function"))]
@@ -233,7 +234,6 @@ use func::calc_typed_method_hash;
 use func::{calc_fn_hash, calc_fn_hash_full, calc_var_hash};
 pub use func::{plugin, FuncArgs, NativeCallContext, RegisterNativeFunction};
 pub use module::{FnNamespace, Module};
-use restore::RestoreOnDrop;
 pub use rhai_codegen::*;
 #[cfg(not(feature = "no_time"))]
 pub use types::Instant;
diff --git a/src/module/mod.rs b/src/module/mod.rs
index 84b27c4b..26dbca16 100644
--- a/src/module/mod.rs
+++ b/src/module/mod.rs
@@ -195,22 +195,22 @@ pub struct Module {
     /// Custom types.
     custom_types: Option<Box<CustomTypesCollection>>,
     /// Sub-modules.
-    modules: Option<Box<BTreeMap<Identifier, SharedModule>>>,
+    modules: Option<BTreeMap<Identifier, SharedModule>>,
     /// [`Module`] variables.
-    variables: Option<Box<BTreeMap<Identifier, Dynamic>>>,
+    variables: Option<BTreeMap<Identifier, Dynamic>>,
     /// Flattened collection of all [`Module`] variables, including those in sub-modules.
-    all_variables: Option<Box<StraightHashMap<Dynamic>>>,
+    all_variables: Option<StraightHashMap<Dynamic>>,
     /// Functions (both native Rust and scripted).
     functions: Option<StraightHashMap<FuncInfo>>,
     /// Flattened collection of all functions, native Rust and scripted.
     /// including those in sub-modules.
-    all_functions: Option<Box<StraightHashMap<CallableFunction>>>,
+    all_functions: Option<StraightHashMap<CallableFunction>>,
     /// Bloom filter on native Rust functions (in scripted hash format) that contain [`Dynamic`] parameters.
     dynamic_functions_filter: Option<Box<BloomFilterU64>>,
     /// Iterator functions, keyed by the type producing the iterator.
-    type_iterators: Option<Box<BTreeMap<TypeId, Shared<IteratorFn>>>>,
+    type_iterators: Option<BTreeMap<TypeId, Shared<IteratorFn>>>,
     /// Flattened collection of iterator functions, including those in sub-modules.
-    all_type_iterators: Option<Box<BTreeMap<TypeId, Shared<IteratorFn>>>>,
+    all_type_iterators: Option<BTreeMap<TypeId, Shared<IteratorFn>>>,
     /// Flags.
     pub(crate) flags: ModuleFlags,
 }
@@ -234,7 +234,7 @@ impl fmt::Debug for Module {
                 "modules",
                 &self
                     .modules
-                    .as_deref()
+                    .as_ref()
                     .into_iter()
                     .flat_map(BTreeMap::keys)
                     .map(SmartString::as_str)
@@ -561,23 +561,23 @@ impl Module {
                 .functions
                 .as_ref()
                 .map_or(true, StraightHashMap::is_empty)
-            && self.variables.as_deref().map_or(true, BTreeMap::is_empty)
-            && self.modules.as_deref().map_or(true, BTreeMap::is_empty)
+            && self.variables.as_ref().map_or(true, BTreeMap::is_empty)
+            && self.modules.as_ref().map_or(true, BTreeMap::is_empty)
             && self
                 .type_iterators
-                .as_deref()
+                .as_ref()
                 .map_or(true, BTreeMap::is_empty)
             && self
                 .all_functions
-                .as_deref()
+                .as_ref()
                 .map_or(true, StraightHashMap::is_empty)
             && self
                 .all_variables
-                .as_deref()
+                .as_ref()
                 .map_or(true, StraightHashMap::is_empty)
             && self
                 .all_type_iterators
-                .as_deref()
+                .as_ref()
                 .map_or(true, BTreeMap::is_empty)
     }
 
@@ -1979,9 +1979,9 @@ impl Module {
     #[must_use]
     pub fn count(&self) -> (usize, usize, usize) {
         (
-            self.variables.as_deref().map_or(0, BTreeMap::len),
+            self.variables.as_ref().map_or(0, BTreeMap::len),
             self.functions.as_ref().map_or(0, StraightHashMap::len),
-            self.type_iterators.as_deref().map_or(0, BTreeMap::len),
+            self.type_iterators.as_ref().map_or(0, BTreeMap::len),
         )
     }
 
@@ -1989,7 +1989,7 @@ impl Module {
     #[inline]
     pub fn iter_sub_modules(&self) -> impl Iterator<Item = (&str, &SharedModule)> {
         self.modules
-            .as_deref()
+            .as_ref()
             .into_iter()
             .flatten()
             .map(|(k, m)| (k.as_str(), m))
@@ -1999,7 +1999,7 @@ impl Module {
     #[inline]
     pub fn iter_var(&self) -> impl Iterator<Item = (&str, &Dynamic)> {
         self.variables
-            .as_deref()
+            .as_ref()
             .into_iter()
             .flatten()
             .map(|(k, v)| (k.as_str(), v))
@@ -2392,7 +2392,7 @@ impl Module {
 
         if !self.is_indexed() {
             let mut path = Vec::with_capacity(4);
-            let mut variables = new_hash_map(self.variables.as_deref().map_or(0, BTreeMap::len));
+            let mut variables = new_hash_map(self.variables.as_ref().map_or(0, BTreeMap::len));
             let mut functions =
                 new_hash_map(self.functions.as_ref().map_or(0, StraightHashMap::len));
             let mut type_iterators = BTreeMap::new();
diff --git a/src/optimizer.rs b/src/optimizer.rs
index dd8166c0..124e7d95 100644
--- a/src/optimizer.rs
+++ b/src/optimizer.rs
@@ -840,6 +840,22 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
         // return expr;
         Stmt::Return(Some(ref mut expr), ..) => optimize_expr(expr, state, false),
 
+        // Share nothing
+        #[cfg(not(feature = "no_closure"))]
+        Stmt::Share(x) if x.is_empty() => {
+            state.set_dirty();
+            *stmt = Stmt::Noop(Position::NONE);
+        }
+        // Share constants
+        #[cfg(not(feature = "no_closure"))]
+        Stmt::Share(x) => {
+            let len = x.len();
+            x.retain(|(v, _, _)| !state.find_constant(v).is_some());
+            if x.len() != len {
+                state.set_dirty();
+            }
+        }
+
         // All other statements - skip
         _ => (),
     }
@@ -1262,7 +1278,7 @@ impl Engine {
         #[cfg(not(feature = "no_module"))]
         if self
             .global_sub_modules
-            .as_deref()
+            .as_ref()
             .into_iter()
             .flatten()
             .any(|(_, m)| m.contains_qualified_fn(hash))
diff --git a/src/packages/lang_core.rs b/src/packages/lang_core.rs
index c7041387..26815f43 100644
--- a/src/packages/lang_core.rs
+++ b/src/packages/lang_core.rs
@@ -273,7 +273,7 @@ fn collect_fn_metadata(
     #[cfg(not(feature = "no_module"))]
     ctx.engine()
         .global_sub_modules
-        .as_deref()
+        .as_ref()
         .into_iter()
         .flatten()
         .flat_map(|(_, m)| m.iter_script_fn())
diff --git a/src/parser.rs b/src/parser.rs
index 207a53a6..2300b402 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -261,7 +261,7 @@ impl<'e, 's> ParseState<'e, 's> {
         text: impl AsRef<str> + Into<ImmutableString>,
     ) -> ImmutableString {
         self.interned_strings.get_with_mapper(
-            crate::engine::FN_GET,
+            b'g',
             |s| crate::engine::make_getter(s.as_ref()).into(),
             text,
         )
@@ -276,7 +276,7 @@ impl<'e, 's> ParseState<'e, 's> {
         text: impl AsRef<str> + Into<ImmutableString>,
     ) -> ImmutableString {
         self.interned_strings.get_with_mapper(
-            crate::engine::FN_SET,
+            b's',
             |s| crate::engine::make_setter(s.as_ref()).into(),
             text,
         )
@@ -601,7 +601,7 @@ impl Engine {
                             .any(|m| m.as_str() == root)
                         && !self
                             .global_sub_modules
-                            .as_deref()
+                            .as_ref()
                             .map_or(false, |m| m.contains_key(root))
                     {
                         return Err(
@@ -676,7 +676,7 @@ impl Engine {
                                 .any(|m| m.as_str() == root)
                             && !self
                                 .global_sub_modules
-                                .as_deref()
+                                .as_ref()
                                 .map_or(false, |m| m.contains_key(root))
                         {
                             return Err(
@@ -908,7 +908,7 @@ impl Engine {
         let mut settings = settings;
         settings.pos = eat_token(input, Token::LeftBracket);
 
-        let mut array = StaticVec::new_const();
+        let mut array = FnArgsVec::new_const();
 
         loop {
             const MISSING_RBRACKET: &str = "to end this array literal";
@@ -1501,7 +1501,7 @@ impl Engine {
 
             // Interpolated string
             Token::InterpolatedString(..) => {
-                let mut segments = StaticVec::<Expr>::new();
+                let mut segments = FnArgsVec::new_const();
                 let settings = settings.level_up()?;
 
                 match input.next().expect(NEVER_ENDS) {
@@ -1577,12 +1577,12 @@ impl Engine {
             Token::Custom(key) | Token::Reserved(key) | Token::Identifier(key)
                 if self
                     .custom_syntax
-                    .as_deref()
+                    .as_ref()
                     .map_or(false, |m| m.contains_key(&**key)) =>
             {
                 let (key, syntax) = self
                     .custom_syntax
-                    .as_deref()
+                    .as_ref()
                     .and_then(|m| m.get_key_value(&**key))
                     .unwrap();
                 let (.., pos) = input.next().expect(NEVER_ENDS);
@@ -1888,7 +1888,7 @@ impl Engine {
                             .any(|m| m.as_str() == root)
                         && !self
                             .global_sub_modules
-                            .as_deref()
+                            .as_ref()
                             .map_or(false, |m| m.contains_key(root))
                     {
                         return Err(
@@ -2303,7 +2303,7 @@ impl Engine {
                 #[cfg(not(feature = "no_custom_syntax"))]
                 Token::Custom(c) => self
                     .custom_keywords
-                    .as_deref()
+                    .as_ref()
                     .and_then(|m| m.get(&**c))
                     .copied()
                     .ok_or_else(|| PERR::Reserved(c.to_string()).into_err(*current_pos))?,
@@ -2329,7 +2329,7 @@ impl Engine {
                 #[cfg(not(feature = "no_custom_syntax"))]
                 Token::Custom(c) => self
                     .custom_keywords
-                    .as_deref()
+                    .as_ref()
                     .and_then(|m| m.get(&**c))
                     .copied()
                     .ok_or_else(|| PERR::Reserved(c.to_string()).into_err(*next_pos))?,
@@ -2434,7 +2434,7 @@ impl Engine {
                 Token::Custom(s)
                     if self
                         .custom_keywords
-                        .as_deref()
+                        .as_ref()
                         .and_then(|m| m.get(s.as_str()))
                         .map_or(false, Option::is_some) =>
                 {
@@ -3612,31 +3612,39 @@ impl Engine {
 
         // Parse type for `this` pointer
         #[cfg(not(feature = "no_object"))]
-        let ((token, pos), this_type) = match token {
-            Token::StringConstant(s) if input.peek().expect(NEVER_ENDS).0 == Token::Period => {
-                eat_token(input, Token::Period);
-                let s = match s.as_str() {
-                    "int" => state.get_interned_string(std::any::type_name::<crate::INT>()),
-                    #[cfg(not(feature = "no_float"))]
-                    "float" => state.get_interned_string(std::any::type_name::<crate::FLOAT>()),
-                    _ => state.get_interned_string(*s),
-                };
-                (input.next().expect(NEVER_ENDS), Some(s))
+        let ((token, pos), this_type) = {
+            let (next_token, next_pos) = input.peek().expect(NEVER_ENDS);
+
+            match token {
+                Token::StringConstant(s) if next_token == &Token::Period => {
+                    eat_token(input, Token::Period);
+                    let s = match s.as_str() {
+                        "int" => state.get_interned_string(std::any::type_name::<crate::INT>()),
+                        #[cfg(not(feature = "no_float"))]
+                        "float" => state.get_interned_string(std::any::type_name::<crate::FLOAT>()),
+                        _ => state.get_interned_string(*s),
+                    };
+                    (input.next().expect(NEVER_ENDS), Some(s))
+                }
+                Token::StringConstant(..) => {
+                    return Err(PERR::MissingToken(
+                        Token::Period.into(),
+                        "after the type name for 'this'".into(),
+                    )
+                    .into_err(*next_pos))
+                }
+                Token::Identifier(s) if next_token == &Token::Period => {
+                    eat_token(input, Token::Period);
+                    let s = match s.as_str() {
+                        "int" => state.get_interned_string(std::any::type_name::<crate::INT>()),
+                        #[cfg(not(feature = "no_float"))]
+                        "float" => state.get_interned_string(std::any::type_name::<crate::FLOAT>()),
+                        _ => state.get_interned_string(*s),
+                    };
+                    (input.next().expect(NEVER_ENDS), Some(s))
+                }
+                _ => ((token, pos), None),
             }
-            Token::StringConstant(..) => {
-                return Err(PERR::MissingSymbol(".".to_string()).into_err(pos))
-            }
-            Token::Identifier(s) if input.peek().expect(NEVER_ENDS).0 == Token::Period => {
-                eat_token(input, Token::Period);
-                let s = match s.as_str() {
-                    "int" => state.get_interned_string(std::any::type_name::<crate::INT>()),
-                    #[cfg(not(feature = "no_float"))]
-                    "float" => state.get_interned_string(std::any::type_name::<crate::FLOAT>()),
-                    _ => state.get_interned_string(*s),
-                };
-                (input.next().expect(NEVER_ENDS), Some(s))
-            }
-            _ => ((token, pos), None),
         };
 
         let name = match token.into_function_name_for_override() {
@@ -3921,7 +3929,7 @@ impl Engine {
         let expr = self.parse_expr(&mut input, state, &mut functions, settings)?;
 
         #[cfg(feature = "no_function")]
-        assert!(functions.is_empty());
+        debug_assert!(functions.is_empty());
 
         match input.peek().expect(NEVER_ENDS) {
             (Token::EOF, ..) => (),
diff --git a/src/serde/metadata.rs b/src/serde/metadata.rs
index 719298eb..4eec9053 100644
--- a/src/serde/metadata.rs
+++ b/src/serde/metadata.rs
@@ -182,7 +182,7 @@ pub fn gen_metadata_to_json(
     let mut global = ModuleMetadata::new();
 
     #[cfg(not(feature = "no_module"))]
-    for (name, m) in engine.global_sub_modules.as_deref().into_iter().flatten() {
+    for (name, m) in engine.global_sub_modules.as_ref().into_iter().flatten() {
         global.modules.insert(name, m.as_ref().into());
     }
 
diff --git a/src/tokenizer.rs b/src/tokenizer.rs
index 27d0cf6b..2e0e009c 100644
--- a/src/tokenizer.rs
+++ b/src/tokenizer.rs
@@ -514,117 +514,117 @@ static KEYWORDS_LIST: [(&str, Token); 153] = [
 const MIN_RESERVED_LEN: usize = 1;
 const MAX_RESERVED_LEN: usize = 10;
 const MIN_RESERVED_HASH_VALUE: usize = 1;
-const MAX_RESERVED_HASH_VALUE: usize = 112;
+const MAX_RESERVED_HASH_VALUE: usize = 149;
 
 static RESERVED_ASSOC_VALUES: [u8; 256] = [
-    113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,
-    113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 35, 113, 45, 25, 113,
-    113, 113, 60, 55, 50, 50, 113, 15, 0, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,
-    10, 85, 45, 5, 55, 50, 5, 113, 113, 113, 113, 113, 85, 113, 113, 113, 113, 113, 113, 113, 113,
-    113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 35, 113, 113, 113, 55, 113, 10, 40,
-    5, 0, 5, 35, 10, 5, 0, 113, 113, 20, 25, 5, 45, 0, 113, 0, 0, 0, 15, 30, 20, 25, 20, 113, 113,
-    20, 113, 0, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,
-    113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,
-    113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,
-    113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,
-    113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,
-    113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,
-    113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,
+    150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150,
+    150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 10, 150, 5, 35, 150, 150,
+    150, 45, 35, 30, 30, 150, 20, 15, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 35,
+    30, 15, 5, 25, 0, 25, 150, 150, 150, 150, 150, 65, 150, 150, 150, 150, 150, 150, 150, 150, 150,
+    150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 40, 150, 150, 150, 150, 150, 0, 150, 0,
+    0, 0, 15, 45, 10, 15, 150, 150, 35, 25, 10, 50, 0, 150, 5, 0, 15, 0, 5, 25, 45, 15, 150, 150,
+    25, 150, 20, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150,
+    150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150,
+    150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150,
+    150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150,
+    150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150,
+    150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150,
+    150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150, 150,
 ];
-static RESERVED_LIST: [(&str, bool, bool, bool); 113] = [
+static RESERVED_LIST: [(&str, bool, bool, bool); 150] = [
     ("", false, false, false),
-    ("~", true, false, false),
-    ("is", true, false, false),
-    ("...", true, false, false),
-    ("", false, false, false),
-    ("print", true, true, false),
-    ("@", true, false, false),
-    ("private", cfg!(feature = "no_function"), false, false),
-    ("", false, false, false),
-    ("this", true, false, false),
-    ("", false, false, false),
-    ("thread", true, false, false),
+    ("?", true, false, false),
     ("as", cfg!(feature = "no_module"), false, false),
-    ("", false, false, false),
-    ("", false, false, false),
-    ("spawn", true, false, false),
-    ("static", true, false, false),
-    (":=", true, false, false),
-    ("===", true, false, false),
-    ("case", true, false, false),
-    ("super", true, false, false),
-    ("shared", true, false, false),
-    ("package", true, false, false),
     ("use", true, false, false),
-    ("with", true, false, false),
-    ("curry", true, true, true),
-    ("$", true, false, false),
-    ("type_of", true, true, true),
-    ("nil", true, false, false),
-    ("sync", true, false, false),
-    ("yield", true, false, false),
-    ("import", cfg!(feature = "no_module"), false, false),
-    ("--", true, false, false),
-    ("new", true, false, false),
-    ("exit", true, false, false),
+    ("case", true, false, false),
     ("async", true, false, false),
-    ("export", cfg!(feature = "no_module"), false, false),
-    ("!.", true, false, false),
+    ("public", true, false, false),
+    ("package", true, false, false),
     ("", false, false, false),
-    ("call", true, true, true),
-    ("match", true, false, false),
     ("", false, false, false),
-    ("fn", cfg!(feature = "no_function"), false, false),
-    ("var", true, false, false),
-    ("null", true, false, false),
-    ("await", true, false, false),
+    ("super", true, false, false),
     ("#", true, false, false),
+    ("private", cfg!(feature = "no_function"), false, false),
+    ("var", true, false, false),
+    ("protected", true, false, false),
+    ("spawn", true, false, false),
+    ("shared", true, false, false),
+    ("is", true, false, false),
+    ("===", true, false, false),
+    ("sync", true, false, false),
+    ("curry", true, true, true),
+    ("static", true, false, false),
     ("default", true, false, false),
     ("!==", true, false, false),
-    ("eval", true, true, false),
-    ("debug", true, true, false),
-    ("?", true, false, false),
+    ("is_shared", cfg!(not(feature = "no_closure")), true, true),
+    ("print", true, true, false),
+    ("", false, false, false),
+    ("#!", true, false, false),
+    ("", false, false, false),
+    ("this", true, false, false),
+    ("is_def_var", true, true, false),
+    ("thread", true, false, false),
     ("?.", cfg!(feature = "no_object"), false, false),
     ("", false, false, false),
-    ("protected", true, false, false),
+    ("is_def_fn", cfg!(not(feature = "no_function")), true, false),
+    ("yield", true, false, false),
+    ("", false, false, false),
+    ("fn", cfg!(feature = "no_function"), false, false),
+    ("new", true, false, false),
+    ("call", true, true, true),
+    ("match", true, false, false),
+    ("~", true, false, false),
+    ("!.", true, false, false),
+    ("", false, false, false),
+    ("eval", true, true, false),
+    ("await", true, false, false),
+    ("", false, false, false),
+    (":=", true, false, false),
+    ("...", true, false, false),
+    ("null", true, false, false),
+    ("debug", true, true, false),
+    ("@", true, false, false),
+    ("type_of", true, true, true),
+    ("", false, false, false),
+    ("with", true, false, false),
     ("", false, false, false),
     ("", false, false, false),
-    ("go", true, false, false),
-    ("", false, false, false),
-    ("goto", true, false, false),
-    ("", false, false, false),
-    ("public", true, false, false),
     ("<-", true, false, false),
     ("", false, false, false),
-    ("is_def_fn", cfg!(not(feature = "no_function")), true, false),
-    ("is_def_var", true, true, false),
+    ("void", true, false, false),
     ("", false, false, false),
+    ("import", cfg!(feature = "no_module"), false, false),
+    ("--", true, false, false),
+    ("nil", true, false, false),
+    ("exit", true, false, false),
+    ("", false, false, false),
+    ("export", cfg!(feature = "no_module"), false, false),
     ("<|", true, false, false),
-    ("::<", true, false, false),
     ("", false, false, false),
     ("", false, false, false),
     ("", false, false, false),
+    ("$", true, false, false),
     ("->", true, false, false),
     ("", false, false, false),
     ("", false, false, false),
     ("", false, false, false),
-    ("module", true, false, false),
+    ("", false, false, false),
     ("|>", true, false, false),
     ("", false, false, false),
-    ("void", true, false, false),
-    ("", false, false, false),
-    ("", false, false, false),
-    ("#!", true, false, false),
-    ("", false, false, false),
-    ("", false, false, false),
     ("", false, false, false),
     ("", false, false, false),
+    ("module", true, false, false),
     ("?[", cfg!(feature = "no_index"), false, false),
     ("", false, false, false),
     ("", false, false, false),
     ("", false, false, false),
     ("", false, false, false),
     ("Fn", true, true, false),
+    ("::<", true, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("++", true, false, false),
     ("", false, false, false),
     ("", false, false, false),
     ("", false, false, false),
@@ -634,17 +634,54 @@ static RESERVED_LIST: [(&str, bool, bool, bool); 113] = [
     ("", false, false, false),
     ("", false, false, false),
     ("", false, false, false),
-    ("++", true, false, false),
-    ("", false, false, false),
-    ("", false, false, false),
-    ("", false, false, false),
-    ("", false, false, false),
     ("*)", true, false, false),
     ("", false, false, false),
     ("", false, false, false),
     ("", false, false, false),
     ("", false, false, false),
     ("(*", true, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("", false, false, false),
+    ("go", true, false, false),
+    ("", false, false, false),
+    ("goto", true, false, false),
 ];
 
 impl Token {
@@ -875,12 +912,13 @@ impl Token {
         // by GNU `gperf` on the list of keywords.
         let utf8 = syntax.as_bytes();
         let len = utf8.len();
-        let mut hash_val = len;
 
         if !(MIN_KEYWORD_LEN..=MAX_KEYWORD_LEN).contains(&len) {
             return None;
         }
 
+        let mut hash_val = len;
+
         match len {
             1 => (),
             _ => hash_val += KEYWORD_ASSOC_VALUES[(utf8[1] as usize) + 1] as usize,
@@ -1219,12 +1257,12 @@ pub fn parse_string_literal(
                 ch
             }
             None if verbatim => {
-                assert_eq!(escape, "", "verbatim strings should not have any escapes");
+                debug_assert_eq!(escape, "", "verbatim strings should not have any escapes");
                 pos.advance();
                 break;
             }
             None if allow_line_continuation && !escape.is_empty() => {
-                assert_eq!(escape, "\\", "unexpected escape {escape} at end of line");
+                debug_assert_eq!(escape, "\\", "unexpected escape {} at end of line", escape);
                 pos.advance();
                 break;
             }
@@ -1343,14 +1381,14 @@ pub fn parse_string_literal(
 
             // Verbatim
             '\n' if verbatim => {
-                assert_eq!(escape, "", "verbatim strings should not have any escapes");
+                debug_assert_eq!(escape, "", "verbatim strings should not have any escapes");
                 pos.new_line();
                 result.push(next_char);
             }
 
             // Line continuation
             '\n' if allow_line_continuation && !escape.is_empty() => {
-                assert_eq!(escape, "\\", "unexpected escape {escape} at end of line");
+                debug_assert_eq!(escape, "\\", "unexpected escape {} at end of line", escape);
                 escape.clear();
                 pos.new_line();
 
@@ -2306,8 +2344,10 @@ pub fn is_id_continue(x: char) -> bool {
 /// The first `bool` indicates whether it is a reserved keyword or symbol.
 ///
 /// The second `bool` indicates whether the keyword can be called normally as a function.
+/// `false` if it is not a reserved keyword.
 ///
 /// The third `bool` indicates whether the keyword can be called in method-call style.
+/// `false` if it is not a reserved keyword or it cannot be called as a function.
 #[inline]
 #[must_use]
 pub fn is_reserved_keyword_or_symbol(syntax: &str) -> (bool, bool, bool) {
@@ -2315,16 +2355,19 @@ pub fn is_reserved_keyword_or_symbol(syntax: &str) -> (bool, bool, bool) {
     // by GNU `gperf` on the list of keywords.
     let utf8 = syntax.as_bytes();
     let len = utf8.len();
-    let rounds = len.min(3);
-    let mut hash_val = len;
 
     if !(MIN_RESERVED_LEN..=MAX_RESERVED_LEN).contains(&len) {
         return (false, false, false);
     }
 
-    for x in 0..rounds {
-        hash_val += RESERVED_ASSOC_VALUES[utf8[rounds - 1 - x] as usize] as usize;
+    let mut hash_val = len;
+
+    match len {
+        1 => (),
+        _ => hash_val += RESERVED_ASSOC_VALUES[utf8[1] as usize] as usize,
     }
+    hash_val += RESERVED_ASSOC_VALUES[utf8[0] as usize] as usize;
+    hash_val += RESERVED_ASSOC_VALUES[utf8[len - 1] as usize] as usize;
 
     if !(MIN_RESERVED_HASH_VALUE..=MAX_RESERVED_HASH_VALUE).contains(&hash_val) {
         return (false, false, false);
@@ -2332,13 +2375,12 @@ pub fn is_reserved_keyword_or_symbol(syntax: &str) -> (bool, bool, bool) {
 
     match RESERVED_LIST[hash_val] {
         ("", ..) => (false, false, false),
-        (s, true, a, b) => (
+        (s, true, a, b) => {
             // Fail early to avoid calling memcmp().
             // Since we are already working with bytes, mind as well check the first one.
-            s.len() == len && s.as_bytes()[0] == utf8[0] && s == syntax,
-            a,
-            b,
-        ),
+            let is_reserved = s.len() == len && s.as_bytes()[0] == utf8[0] && s == syntax;
+            (is_reserved, is_reserved && a, is_reserved && a && b)
+        }
         _ => (false, false, false),
     }
 }
@@ -2450,7 +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_deref().map_or(false, |m| m.contains_key(&*s)),
+                    self.engine.custom_keywords.as_ref().map_or(false, |m| m.contains_key(&*s)),
                     #[cfg(feature = "no_custom_syntax")]
                     false
                 )
@@ -2487,7 +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_deref().map_or(false,|m| m.contains(token)) => {
+                (token, false) if self.engine.disabled_symbols.as_ref().map_or(false,|m| m.contains(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())
                 },
@@ -2496,13 +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_deref().map_or(false,|m| m.contains_key(&*s)) => {
+            Some((Token::Identifier(s), pos)) if self.engine.custom_keywords.as_ref().map_or(false,|m| m.contains_key(&*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_deref().map_or(false,|m| m.contains_key(token.literal_syntax())) => {
-                if self.engine.disabled_symbols.as_deref().map_or(false,|m| m.contains(token.literal_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())) {
                     // Disabled standard keyword/symbol
                     (Token::Custom(Box::new(token.literal_syntax().into())), pos)
                 } else {
@@ -2511,7 +2553,7 @@ impl<'a> Iterator for TokenIterator<'a> {
                 }
             }
             // Disabled symbol
-            Some((token, pos)) if token.is_literal() && self.engine.disabled_symbols.as_deref().map_or(false,|m| m.contains(token.literal_syntax())) => {
+            Some((token, pos)) if token.is_literal() && self.engine.disabled_symbols.as_ref().map_or(false,|m| m.contains(token.literal_syntax())) => {
                 (Token::Reserved(Box::new(token.literal_syntax().into())), pos)
             }
             // Normal symbol
diff --git a/src/types/interner.rs b/src/types/interner.rs
index 118950cf..22e06fef 100644
--- a/src/types/interner.rs
+++ b/src/types/interner.rs
@@ -62,7 +62,7 @@ impl StringsInterner {
     #[inline(always)]
     #[must_use]
     pub fn get<S: AsRef<str> + Into<ImmutableString>>(&mut self, text: S) -> ImmutableString {
-        self.get_with_mapper("", Into::into, text)
+        self.get_with_mapper(0, Into::into, text)
     }
 
     /// Get an identifier from a text string, adding it to the interner if necessary.
@@ -70,19 +70,19 @@ impl StringsInterner {
     #[must_use]
     pub fn get_with_mapper<S: AsRef<str>>(
         &mut self,
-        category: &str,
+        category: u8,
         mapper: impl FnOnce(S) -> ImmutableString,
         text: S,
     ) -> ImmutableString {
         let key = text.as_ref();
 
         let hasher = &mut get_hasher();
-        category.hash(hasher);
+        hasher.write_u8(category);
         key.hash(hasher);
         let hash = hasher.finish();
 
-        // Cache long strings only on the second try to avoid caching "one-hit wonders".
-        if key.len() > MAX_STRING_LEN && self.bloom_filter.is_absent_and_set(hash) {
+        // Do not cache long strings and avoid caching "one-hit wonders".
+        if key.len() > MAX_STRING_LEN || self.bloom_filter.is_absent_and_set(hash) {
             return mapper(text);
         }
 
diff --git a/tests/method_call.rs b/tests/method_call.rs
index 824f1c72..577447e7 100644
--- a/tests/method_call.rs
+++ b/tests/method_call.rs
@@ -108,6 +108,15 @@ fn test_method_call_typed() -> Result<(), Box<EvalAltResult>> {
         TestStruct { x: 1002 }
     );
 
+    assert!(engine.eval::<bool>(
+        r#"
+            fn "Test-Struct#ABC".foo(x) {
+                this.update(x);
+            }
+            is_def_fn("Test-Struct#ABC", "foo", 1)
+        "#
+    )?);
+
     assert!(matches!(
         *engine
             .run(
diff --git a/tools/keywords.txt b/tools/keywords.txt
index 33375c57..4d9746f3 100644
--- a/tools/keywords.txt
+++ b/tools/keywords.txt
@@ -3,7 +3,7 @@
 //
 // Generate the output table via:
 // ```bash
-// gperf -t keywords.txt
+// gperf keywords.txt
 // ```
 //
 // Since GNU gperf does not produce Rust output, the ANSI-C output must be hand-edited and
@@ -17,86 +17,89 @@
 // * Copy the `wordlist` array into `KEYWORDS_LIST` with the following modifications:
 //   - Remove the `#line` comments
 //   - Change the entry wrapping `{ .. }` into tuples `( .. )`
-//   - Replace all entries `("")` by `("", Token::EOF)`
 //   - Put feature flags on the appropriate lines, and duplicating lines that maps to `Token::EOF`
 //     for the opposite feature flags
 //
+%global-table
+%struct-type
+%omit-struct-type
+%define initializer-suffix ,Token::EOF
 struct keyword;
 %%
-"{",        Token::LeftBrace
-"}",        Token::RightBrace
-"(",        Token::LeftParen
-")",        Token::RightParen
-"[",        Token::LeftBracket
-"]",        Token::RightBracket
-"()",       Token::Unit
-"+",        Token::Plus
-"-",        Token::Minus
-"*",        Token::Multiply
-"/",        Token::Divide
-";",        Token::SemiColon
-":",        Token::Colon
-"::",       Token::DoubleColon
-"=>",       Token::DoubleArrow
-"_",        Token::Underscore
-",",        Token::Comma
-".",        Token::Period
-"?.",       Token::Elvis
-"??",       Token::DoubleQuestion
-"?[",       Token::QuestionBracket
-"..",       Token::ExclusiveRange
-"..=",      Token::InclusiveRange
+{,          Token::LeftBrace
+},          Token::RightBrace
+(,          Token::LeftParen
+),          Token::RightParen
+[,          Token::LeftBracket
+],          Token::RightBracket
+(),         Token::Unit
++,          Token::Plus
+-,          Token::Minus
+*,          Token::Multiply
+/,          Token::Divide
+;,          Token::SemiColon
+:,          Token::Colon
+::,         Token::DoubleColon
+=>,         Token::DoubleArrow
+_,          Token::Underscore
+,,          Token::Comma
+.,          Token::Period
+?.,         Token::Elvis
+??,         Token::DoubleQuestion
+?[,         Token::QuestionBracket
+..,         Token::ExclusiveRange
+..=,        Token::InclusiveRange
 "#{",       Token::MapStart
-"=",        Token::Equals
-"true",     Token::True
-"false",    Token::False
-"let",      Token::Let
-"const",    Token::Const
-"if",       Token::If
-"else",     Token::Else
-"switch",   Token::Switch
-"do",       Token::Do
-"while",    Token::While
-"until",    Token::Until
-"loop",     Token::Loop
-"for",      Token::For
-"in",       Token::In
-"!in",      Token::NotIn
-"<",        Token::LessThan
-">",        Token::GreaterThan
-"<=",       Token::LessThanEqualsTo
-">=",       Token::GreaterThanEqualsTo
-"==",       Token::EqualsTo
-"!=",       Token::NotEqualsTo
-"!",        Token::Bang
-"|",        Token::Pipe
-"||",       Token::Or
-"&",        Token::Ampersand
-"&&",       Token::And
-"continue", Token::Continue
-"break",    Token::Break
-"return",   Token::Return
-"throw",    Token::Throw
-"try",      Token::Try
-"catch",    Token::Catch
-"+=",       Token::PlusAssign
-"-=",       Token::MinusAssign
-"*=",       Token::MultiplyAssign
-"/=",       Token::DivideAssign
-"<<=",      Token::LeftShiftAssign
-">>=",      Token::RightShiftAssign
-"&=",       Token::AndAssign
-"|=",       Token::OrAssign
-"^=",       Token::XOrAssign
-"<<",       Token::LeftShift
-">>",       Token::RightShift
-"^",        Token::XOr
-"%",        Token::Modulo
-"%=",       Token::ModuloAssign
-"**",       Token::PowerOf
-"**=",      Token::PowerOfAssign
-"fn",       Token::Fn
-"private",  Token::Private
-"import",   Token::Import
-"export",   Token::Export
-"as",       Token::As
+=,          Token::Equals
+true,       Token::True
+false,      Token::False
+let,        Token::Let
+const,      Token::Const
+if,         Token::If
+else,       Token::Else
+switch,     Token::Switch
+do,         Token::Do
+while,      Token::While
+until,      Token::Until
+loop,       Token::Loop
+for,        Token::For
+in,         Token::In
+!in,        Token::NotIn
+<,          Token::LessThan
+>,          Token::GreaterThan
+<=,         Token::LessThanEqualsTo
+>=,         Token::GreaterThanEqualsTo
+==,         Token::EqualsTo
+!=,         Token::NotEqualsTo
+!,          Token::Bang
+|,          Token::Pipe
+||,         Token::Or
+&,          Token::Ampersand
+&&,         Token::And
+continue,   Token::Continue
+break,      Token::Break
+return,     Token::Return
+throw,      Token::Throw
+try,        Token::Try
+catch,      Token::Catch
++=,         Token::PlusAssign
+-=,         Token::MinusAssign
+*=,         Token::MultiplyAssign
+/=,         Token::DivideAssign
+<<=,        Token::LeftShiftAssign
+>>=,        Token::RightShiftAssign
+&=,         Token::AndAssign
+|=,         Token::OrAssign
+^=,         Token::XOrAssign
+<<,         Token::LeftShift
+>>,         Token::RightShift
+^,          Token::XOr
+%,          Token::Modulo
+%=,         Token::ModuloAssign
+**,         Token::PowerOf
+**=,        Token::PowerOfAssign
+fn,         Token::Fn
+private,    Token::Private
+import,     Token::Import
+export,     Token::Export
+as,         Token::As
diff --git a/tools/reserved.txt b/tools/reserved.txt
index 2dbe79cd..4ae6d8d2 100644
--- a/tools/reserved.txt
+++ b/tools/reserved.txt
@@ -7,7 +7,7 @@
 //
 // Generate the output table via:
 // ```bash
-// gperf -t reserved.txt
+// gperf reserved.txt
 // ```
 //
 // Since GNU gperf does not produce Rust output, the ANSI-C output must be hand-edited and
@@ -21,73 +21,88 @@
 // * Copy the `wordlist` array into `RESERVED_LIST` with the following modifications:
 //   - Remove the `#line` comments
 //   - Change the entry wrapping `{ .. }` into tuples `( .. )`
-//   - Replace all entries `("")` by `("", false, false, false)`
 //   - Feature flags can be incorporated directly into the output via the `cfg!` macro
 //
+%global-table
+%struct-type
+%omit-struct-type
+%define initializer-suffix ,false,false,false
 struct reserved;
 %%
-"?.",           cfg!(feature = "no_object"), false, false
-"?[",           cfg!(feature = "no_index"), false, false
-"fn",           cfg!(feature = "no_function"), false, false
-"private",      cfg!(feature = "no_function"), false, false
-"import",       cfg!(feature = "no_module"), false, false
-"export",       cfg!(feature = "no_module"), false, false
-"as",           cfg!(feature = "no_module"), false, false
-"===",          true, false, false
-"!==",          true, false, false
-"->",           true, false, false
-"<-",           true, false, false
-"?",            true, false, false
-":=",           true, false, false
-":;",           true, false, false
-"~",            true, false, false
-"!.",           true, false, false
-"::<",          true, false, false
-"(*",           true, false, false
-"*)",           true, false, false
+# reserved under certain flags
+#
+?.,             cfg!(feature = no_object), false, false
+?[,             cfg!(feature = no_index), false, false
+fn,             cfg!(feature = no_function), false, false
+private,        cfg!(feature = no_function), false, false
+import,         cfg!(feature = no_module), false, false
+export,         cfg!(feature = no_module), false, false
+as,             cfg!(feature = no_module), false, false
+#   
+# reserved symbols
+#   
+===,            true, false, false
+!==,            true, false, false
+->,             true, false, false
+<-,             true, false, false
+?,              true, false, false
+:=,             true, false, false
+:;,             true, false, false
+~,              true, false, false
+!.,             true, false, false
+::<,            true, false, false
+(*,             true, false, false
+*),             true, false, false
 "#",            true, false, false
 "#!",           true, false, false
-"@",            true, false, false
-"$",            true, false, false
-"++",           true, false, false
-"--",           true, false, false
-"...",          true, false, false
-"<|",           true, false, false
-"|>",           true, false, false
-"public",       true, false, false
-"protected",    true, false, false
-"super",        true, false, false
-"new",          true, false, false
-"use",          true, false, false
-"module",       true, false, false
-"package",      true, false, false
-"var",          true, false, false
-"static",       true, false, false
-"shared",       true, false, false
-"with",         true, false, false
-"is",           true, false, false
-"goto",         true, false, false
-"exit",         true, false, false
-"match",        true, false, false
-"case",         true, false, false
-"default",      true, false, false
-"void",         true, false, false
-"null",         true, false, false
-"nil",          true, false, false
-"spawn",        true, false, false
-"thread",       true, false, false
-"go",           true, false, false
-"sync",         true, false, false
-"async",        true, false, false
-"await",        true, false, false
-"yield",        true, false, false
-"print",        true, true, false
-"debug",        true, true, false
-"type_of",      true, true, true
-"eval",         true, true, false
-"Fn",           true, true, false
-"call",         true, true, true
-"curry",        true, true, true
-"this",         true, false, false
-"is_def_var",   true, true, false
-"is_def_fn",    cfg!(not(feature = "no_function")), true, false
+@,              true, false, false
+$,              true, false, false
+++,             true, false, false
+--,             true, false, false
+...,            true, false, false
+<|,             true, false, false
+|>,             true, false, false
+#   
+# reserved keywords
+#   
+public,         true, false, false
+protected,      true, false, false
+super,          true, false, false
+new,            true, false, false
+use,            true, false, false
+module,         true, false, false
+package,        true, false, false
+var,            true, false, false
+static,         true, false, false
+shared,         true, false, false
+with,           true, false, false
+is,             true, false, false
+goto,           true, false, false
+exit,           true, false, false
+match,          true, false, false
+case,           true, false, false
+default,        true, false, false
+void,           true, false, false
+null,           true, false, false
+nil,            true, false, false
+spawn,          true, false, false
+thread,         true, false, false
+go,             true, false, false
+sync,           true, false, false
+async,          true, false, false
+await,          true, false, false
+yield,          true, false, false
+#   
+# keyword functions
+#   
+print,          true, true, false
+debug,          true, true, false
+type_of,        true, true, true
+eval,           true, true, false
+Fn,             true, true, false
+call,           true, true, true
+curry,          true, true, true
+this,           true, false, false
+is_def_var,     true, true, false
+is_def_fn,      cfg!(not(feature = no_function)), true, false
+is_shared,      cfg!(not(feature = no_closure)), true, true