Address review: merge develop to resolve merge conflicts

Merged origin/develop into the branch. Git auto-merged all files (chaiscript_common.hpp, chaiscript_engine.hpp, chaiscript_eval.hpp, compiled_tests.cpp) without conflicts. Build succeeds and all 391 tests pass. Requested by @lefticus in PR #682 review.
2026-04-30 19:09:26 +08:00 · 2026-04-21 21:25:46 -06:00 · 2026-04-21 21:25:46 -06:00 · e46ccb7d33
commit e46ccb7d33
parent 5cebd2cd22 1cbbba38f9
17 changed files with 1972 additions and 43 deletions
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@ -26,7 +26,7 @@ jobs:
        run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} -DMULTITHREAD_SUPPORT_ENABLED=${{ matrix.multithread }}

      - name: Build
-        run: cmake --build build -j
+        run: cmake --build build

      - name: Test
        run: ctest --test-dir build --output-on-failure
@ -49,7 +49,7 @@ jobs:
        run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} -DMULTITHREAD_SUPPORT_ENABLED=${{ matrix.multithread }}

      - name: Build
-        run: cmake --build build -j
+        run: cmake --build build

      - name: Test
        run: ctest --test-dir build --output-on-failure
@ -71,7 +71,7 @@ jobs:
        run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} -DENABLE_ADDRESS_SANITIZER=ON -DENABLE_UNDEFINED_SANITIZER=ON

      - name: Build
-        run: cmake --build build -j
+        run: cmake --build build

      - name: Test
        run: ctest --test-dir build --output-on-failure
@ -93,7 +93,7 @@ jobs:
        run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} -DENABLE_ADDRESS_SANITIZER=ON -DENABLE_UNDEFINED_SANITIZER=ON

      - name: Build
-        run: cmake --build build -j
+        run: cmake --build build

      - name: Test
        run: ctest --test-dir build --output-on-failure
@ -135,7 +135,7 @@ jobs:
        run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} -DENABLE_THREAD_SANITIZER=ON -DMULTITHREAD_SUPPORT_ENABLED=ON

      - name: Build
-        run: cmake --build build -j
+        run: cmake --build build

      - name: Test
        run: ctest --test-dir build --output-on-failure
@ -157,7 +157,7 @@ jobs:
        run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} -DENABLE_THREAD_SANITIZER=ON -DMULTITHREAD_SUPPORT_ENABLED=ON

      - name: Build
-        run: cmake --build build -j
+        run: cmake --build build

      - name: Test
        run: ctest --test-dir build --output-on-failure
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -440,6 +440,10 @@ if(BUILD_TESTING)
    target_link_libraries(emscripten_eval_test ${LIBS})
    add_test(NAME Emscripten_Eval_Test COMMAND emscripten_eval_test)

+    add_executable(emscripten_exception_test unittests/emscripten_exception_test.cpp)
+    target_link_libraries(emscripten_exception_test ${LIBS})
+    add_test(NAME Emscripten_Exception_Test COMMAND emscripten_exception_test)
+
    add_executable(threading_config_test unittests/threading_config_test.cpp)
    target_link_libraries(threading_config_test ${LIBS})
    add_test(NAME Threading_Config_Test COMMAND threading_config_test)
--- a/cheatsheet.md
+++ b/cheatsheet.md
@ -665,6 +665,124 @@ copy.width = 99
 print(original.width)  // still 10
 ```

+## Enums
+
+ChaiScript supports strongly-typed enums using `enum class` (or equivalently `enum struct`),
+matching C++ scoped-enum semantics. Values are accessed via `::` syntax and are type-safe —
+a plain integer cannot be passed where an enum type is expected.
+
+### Basic Definition
+
+```
+enum class Color { Red, Green, Blue }
+```
+
+Values are auto-numbered starting from 0. Access them with `Color::Red`, `Color::Green`, etc.
+
+### Explicit Values
+
+```
+enum class Priority { Low = 10, Medium = 20, High = 30 }
+```
+
+Auto-numbering continues from the last explicit value:
+
+```
+enum class Status { Pending, Active = 5, Done }
+// Pending = 0, Active = 5, Done = 6
+```
+
+### Specifying an Underlying Type
+
+By default the underlying type is `int`. Use `: type` to choose a different numeric type:
+
+```
+enum class Flags : char { Read = 1, Write = 2, Execute = 4 }
+```
+
+The underlying type must be a numeric type registered in ChaiScript. `string` and other
+non-numeric types cannot be used. The available underlying types are:
+
+| Type | Description |
+|------|-------------|
+| `int` | (default) signed integer |
+| `unsigned_int` | unsigned integer |
+| `long` | signed long |
+| `unsigned_long` | unsigned long |
+| `long_long` | signed long long |
+| `unsigned_long_long` | unsigned long long |
+| `char` | character (8-bit) |
+| `wchar_t` | wide character |
+| `char16_t` | 16-bit character |
+| `char32_t` | 32-bit character |
+| `float` | single-precision float |
+| `double` | double-precision float |
+| `long_double` | extended-precision float |
+| `size_t` | unsigned size type |
+| `int8_t` | signed 8-bit |
+| `int16_t` | signed 16-bit |
+| `int32_t` | signed 32-bit |
+| `int64_t` | signed 64-bit |
+| `uint8_t` | unsigned 8-bit |
+| `uint16_t` | unsigned 16-bit |
+| `uint32_t` | unsigned 32-bit |
+
+### `enum struct` Syntax
+
+`enum struct` is accepted as a synonym for `enum class`, just like in C++:
+
+```
+enum struct Direction { North, East, South, West }
+```
+
+### Constructing from a Value
+
+Each enum type has a constructor that accepts the underlying type. It validates that the
+value matches one of the defined enumerators:
+
+```
+auto c = Color::Color(1)       // creates Color::Green
+Color::Color(52)               // throws: invalid value
+```
+
+### `to_underlying`
+
+Convert an enum value back to its underlying numeric type:
+
+```
+Color::Red.to_underlying()     // 0
+Priority::High.to_underlying() // 30
+```
+
+### Comparison
+
+`==` and `!=` are defined for values of the same enum type:
+
+```
+assert_true(Color::Red == Color::Red)
+assert_true(Color::Red != Color::Green)
+```
+
+### Type-Safe Dispatch
+
+Functions declared with an enum parameter type reject plain integers:
+
+```
+def handle(Color c) { /* ... */ }
+handle(Color::Red)    // ok
+handle(42)            // throws: dispatch error
+```
+
+### Using with `switch`
+
+```
+switch(Color::Green) {
+  case (Color::Red) { print("red"); break }
+  case (Color::Green) { print("green"); break }
+  case (Color::Blue) { print("blue"); break }
+}
+```
+
 ## Dynamic Objects

 All ChaiScript defined types and generic Dynamic_Object support dynamic parameters
@ -711,6 +829,94 @@ class My_Class {
 };
 ```

+## Strong Typedefs
+
+Strong typedefs create distinct types that are not interchangeable with their underlying type
+or with other typedefs of the same underlying type. They use `Dynamic_Object` internally and
+automatically expose operators that the underlying type supports.
+
+### Basic Usage
+
+```
+using Meters = int
+using Seconds = int
+
+var d = Meters(100)
+var t = Seconds(10)
+
+// d and t are distinct types — you cannot accidentally mix them
+// Meters + Seconds would require an explicit conversion
+```
+
+### Arithmetic and Comparison
+
+Operators from the underlying type are forwarded and remain strongly typed:
+
+```
+using Meters = int
+
+var a = Meters(10)
+var b = Meters(20)
+
+var c = a + b        // Meters(30) — result is still Meters
+var bigger = b > a   // true — comparisons return bool
+
+// Compound assignment operators work too
+a += b               // a is now Meters(30)
+```
+
+### String-Based Strong Typedefs
+
+Strong typedefs work with any type, not just numeric types:
+
+```
+using Name = string
+
+var n = Name("Alice")
+var greeting = Name("Hello, ") + Name("world")  // Name — string concatenation is forwarded
+```
+
+### Accessing the Underlying Value
+
+Use `to_underlying` to extract the wrapped value:
+
+```
+using Meters = int
+
+var d = Meters(42)
+var raw = to_underlying(d)  // 42, plain int
+```
+
+### Extending Strong Typedefs
+
+You can add custom operations to strong typedefs just like any other ChaiScript type:
+
+```
+using Meters = int
+using Seconds = int
+using MetersPerSecond = int
+
+def speed(Meters d, Seconds t) {
+  MetersPerSecond(to_underlying(d) / to_underlying(t))
+}
+
+var s = speed(Meters(100), Seconds(10))  // MetersPerSecond(10)
+```
+
+You can also overload operators between different strong typedefs:
+
+```
+using Meters = int
+using Feet = int
+
+def to_feet(Meters m) {
+  Feet((to_underlying(m) * 328) / 100)
+}
+
+var m = Meters(10)
+var f = to_feet(m)  // Feet(32)
+```
+
 ## method_missing

 A function of the signature `method_missing(object, name, param1, param2, param3)` will be called if an appropriate
@ -913,5 +1119,51 @@ The print handler can also be set from within ChaiScript itself via `set_print_h
 set_print_handler(fun(s) { my_custom_log(s) })
 ```

+## Custom File Loading
+
+By default, ChaiScript reads files from the filesystem when `eval_file()` or `use()` is called.
+You can override this behavior on a per-instance basis by setting a custom file reader callback.
+This follows the same pattern as `set_print_handler` and enables use cases such as encrypted
+script files, in-memory virtual filesystems, or platform-specific file access (e.g., Android assets).
+
+```cpp
+chaiscript::ChaiScript chai;
+
+// Provide scripts from an in-memory map instead of the filesystem
+std::map<std::string, std::string> virtual_fs = {
+  {"init.chai", "var x = 42"},
+  {"utils.chai", "def add(a, b) { a + b }"}
+};
+
+chai.set_file_reader([&virtual_fs](const std::string &filename) -> std::string {
+  const auto it = virtual_fs.find(filename);
+  if (it != virtual_fs.end()) {
+    return it->second;
+  }
+  throw chaiscript::exception::file_not_found_error(filename);
+});
+
+chai.eval_file("init.chai"); // evaluates "var x = 42"
+chai.use("utils.chai");      // evaluates "def add(a, b) { a + b }"
+```
+
+The file reader can also be set from within ChaiScript itself via `set_file_reader`:
+
+```chaiscript
+// Override file loading from within a script
+set_file_reader(fun(filename) { return my_custom_read(filename) })
+```
+
+When no custom file reader is set, ChaiScript uses its built-in filesystem reader.
+
 ## Extras
 ChaiScript itself does not provide a link to the math functions defined in `<cmath>`. You can either add them yourself, or use the [ChaiScript_Extras](https://github.com/ChaiScript/ChaiScript_Extras) helper library. (Which also provides some additional string functions.)
+
+## Grammar Railroad Diagrams
+
+A formal EBNF grammar for ChaiScript is available in [`grammar/chaiscript.ebnf`](grammar/chaiscript.ebnf). You can visualize it as navigable railroad diagrams by pasting its contents into one of these tools:
+
+  * [rr — Railroad Diagram Generator (IPv6)](https://www.bottlecaps.de/rr/ui)
+  * [rr — Railroad Diagram Generator (IPv4)](https://rr.red-dove.com/ui)
+
+Open either link, switch to the **Edit Grammar** tab, paste the file contents, then click **View Diagram**.
--- a/emscripten/CMakeLists.txt
+++ b/emscripten/CMakeLists.txt
@ -17,9 +17,14 @@ add_definitions(-DCHAISCRIPT_NO_THREADS -DCHAISCRIPT_NO_DYNLOAD)
 add_executable(chaiscript chaiscript_em.cpp)
 target_include_directories(chaiscript PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../include)

+# Enable WASM exception handling — ChaiScript relies on C++ exceptions for
+# error propagation; without this flag exceptions cause an abort in WASM.
+target_compile_options(chaiscript PRIVATE -fwasm-exceptions)
+
 # Emscripten link flags: enable embind, allow memory growth, export as ES module-compatible
 target_link_options(chaiscript PRIVATE
  --bind
+  -fwasm-exceptions
  -sALLOW_MEMORY_GROWTH=1
  -sEXPORT_ES6=0
  -sMODULARIZE=0
--- a/grammar/chaiscript.ebnf
+++ b/grammar/chaiscript.ebnf
@ -0,0 +1,189 @@
+/*
+ * ChaiScript Grammar — EBNF for Railroad Diagram Generation
+ *
+ * View as navigable railroad diagrams at:
+ *    https://www.bottlecaps.de/rr/ui  (IPv6)
+ *    https://rr.red-dove.com/ui       (IPv4)
+ *
+ * Copy and paste this file into the 'Edit Grammar' tab, then
+ * click 'View Diagram'.
+ *
+ * This grammar uses the notation accepted by
+ * https://github.com/GuntherRademacher/rr :
+ *   - "::=" as rule separator
+ *   - no semicolon at end of rule
+ *   - "?" "+" "*" for repetition
+ *   - C comments
+ */
+
+/* ---- Top-level ---- */
+
+statements           ::= ( def | try | if | while | class | enum
+                           | for | switch | return | break | continue
+                           | equation | block | eol )+
+
+/* ---- Functions ---- */
+
+def                  ::= "def" id ( "::" id )? "(" decl_arg_list ")" eol*
+                           ( ":" guard )? eol* block
+
+lambda               ::= "fun" ( "[" id_arg_list "]" )? "(" decl_arg_list ")" eol* block
+
+guard                ::= operator
+
+/* ---- Exception handling ---- */
+
+try                  ::= "try" eol* block catch* finally?
+catch                ::= "catch" ( "(" arg ")" )? eol* block
+finally              ::= "finally" eol* block
+
+/* ---- Control flow ---- */
+
+if                   ::= "if" "(" equation ( eol equation )? ")" eol* block
+                           ( "else" ( if | eol* block ) )*
+
+while                ::= "while" "(" operator ")" eol* block
+
+for                  ::= "for" "(" ( for_guards | equation ":" equation ) ")" eol* block
+for_guards           ::= equation eol equation eol equation
+
+switch               ::= "switch" "(" operator ")" eol* "{" ( case | default )+ "}"
+case                 ::= "case" "(" operator ")" eol* block
+default              ::= "default" eol* block
+
+/* ---- Classes ---- */
+
+class                ::= "class" id ( ":" id )? eol* class_block
+class_block          ::= "{" class_statements* "}"
+class_statements     ::= def | var_decl | eol
+
+/* ---- Enums ---- */
+
+enum                 ::= "enum" ( "class" | "struct" ) id ( ":" underlying_type )?
+                           "{" enum_entries? "}"
+
+enum_entries         ::= enum_entry ( "," enum_entry )*
+
+enum_entry           ::= id ( "=" integer )?
+
+underlying_type      ::= id
+
+
+/* ---- Blocks & flow keywords ---- */
+
+block                ::= "{" statements* "}"
+return               ::= "return" operator?
+break                ::= "break"
+continue             ::= "continue"
+
+/* ---- Line termination ---- */
+
+eol                  ::= "\n" | "\r\n" | ";"
+
+/* ---- Equations & operators ---- */
+
+equation             ::= operator ( ( "=" | ":=" | "+=" | "-=" | "*=" | "/="
+                           | "%=" | "<<=" | ">>=" | "&=" | "^=" | "|=" )
+                           equation )?
+
+operator             ::= prefix
+                       | value
+                       | operator binary_operator operator
+                       | operator "?" operator ":" operator
+
+prefix               ::= ( "++" | "--" | "-" | "+" | "!" | "~" ) operator
+
+binary_operator      ::= "||" | "&&"
+                       | "|" | "^" | "&"
+                       | "==" | "!="
+                       | "<" | "<=" | ">" | ">="
+                       | "<<" | ">>"
+                       | "+" | "-"
+                       | "*" | "/" | "%"
+
+/* ---- Values & access ---- */
+
+value                ::= var_decl | dot_fun_array | prefix
+
+dot_fun_array        ::= ( lambda | num | quoted_string
+                           | single_quoted_string | raw_string
+                           | paren_expression | inline_container
+                           | id )
+                           ( fun_call | array_call | dot_access )*
+
+fun_call             ::= "(" arg_list ")"
+array_call           ::= "[" operator "]"
+dot_access           ::= "." id
+
+/* ---- Variable declarations ---- */
+
+var_decl             ::= ( "auto" | "var" | "const" ) ( reference | id )
+                       | "global" ( reference | id )
+                       | "attr" id ( "::" id )?
+
+reference            ::= "&" id
+
+/* ---- Parenthesised & inline containers ---- */
+
+paren_expression     ::= "(" operator ")"
+
+inline_container     ::= "[" container_arg_list "]"
+container_arg_list   ::= value_range
+                       | map_pair ( "," map_pair )*
+                       | operator ( "," operator )*
+
+value_range          ::= operator ".." operator
+map_pair             ::= operator ":" operator
+
+/* ---- String literals ---- */
+
+quoted_string        ::= '"' ( char | escape | interpolation )* '"'
+single_quoted_string ::= "'" ( char | escape ) "'"
+raw_string           ::= 'R"' delimiter? "(" char* ")" delimiter? '"'
+delimiter            ::= [a-zA-Z0-9_]+
+interpolation        ::= "${" equation "}"
+
+/* ---- Escape sequences ---- */
+
+escape               ::= "\" ( "'" | '"' | "?" | "\" | "a" | "b"
+                           | "f" | "n" | "r" | "t" | "v" | "$"
+                           | "0"
+                           | "x" hex_digit+
+                           | "u" hex_digit hex_digit hex_digit hex_digit
+                           | "U" hex_digit hex_digit hex_digit hex_digit
+                               hex_digit hex_digit hex_digit hex_digit
+                           | octal_digit+ )
+
+/* ---- Argument lists ---- */
+
+id_arg_list          ::= id ( "," id )*
+decl_arg_list        ::= ( arg ( "," arg )* )?
+arg_list             ::= ( equation ( "," equation )* )?
+arg                  ::= id id?
+
+/* ---- Identifiers ---- */
+
+id                   ::= ( [a-zA-Z_] [a-zA-Z0-9_]* )
+                       | ( "`" [^`]+ "`" )
+                       | "true" | "false"
+                       | "Infinity" | "NaN"
+                       | "_"
+                       | "__LINE__" | "__FILE__" | "__FUNC__" | "__CLASS__"
+
+/* ---- Numeric literals ---- */
+
+num                  ::= hex | binary | float | integer
+
+hex                  ::= "0" ( "x" | "X" ) [0-9a-fA-F]+ int_suffix*
+binary               ::= "0" ( "b" | "B" ) [01]+ int_suffix*
+float                ::= [0-9]+ "." [0-9]+ ( ( "e" | "E" ) ( "+" | "-" )? [0-9]+ )? float_suffix?
+integer              ::= [0-9]+ int_suffix*
+
+int_suffix           ::= "l" | "L" | "ll" | "LL" | "u" | "U"
+float_suffix         ::= "l" | "L" | "f" | "F"
+
+/* ---- Character classes ---- */
+
+octal_digit          ::= [0-7]
+hex_digit            ::= [0-9a-fA-F]
+char                 ::= [^"\]
--- a/include/chaiscript/language/chaiscript_common.hpp
+++ b/include/chaiscript/language/chaiscript_common.hpp
@ -34,7 +34,7 @@ namespace chaiscript {
    template<typename T>
    static bool is_reserved_word(const T &s) noexcept {
      const static std::unordered_set<std::uint32_t>
-          words{utility::hash("def"), utility::hash("fun"), utility::hash("while"), utility::hash("for"), utility::hash("if"), utility::hash("else"), utility::hash("&&"), utility::hash("||"), utility::hash(","), utility::hash("auto"), utility::hash("return"), utility::hash("break"), utility::hash("true"), utility::hash("false"), utility::hash("class"), utility::hash("attr"), utility::hash("var"), utility::hash("global"), utility::hash("GLOBAL"), utility::hash("_"), utility::hash("__LINE__"), utility::hash("__FILE__"), utility::hash("__FUNC__"), utility::hash("__CLASS__"), utility::hash("const")};
+          words{utility::hash("def"), utility::hash("fun"), utility::hash("while"), utility::hash("for"), utility::hash("if"), utility::hash("else"), utility::hash("&&"), utility::hash("||"), utility::hash(","), utility::hash("auto"), utility::hash("return"), utility::hash("break"), utility::hash("true"), utility::hash("false"), utility::hash("class"), utility::hash("attr"), utility::hash("var"), utility::hash("global"), utility::hash("GLOBAL"), utility::hash("_"), utility::hash("__LINE__"), utility::hash("__FILE__"), utility::hash("__FUNC__"), utility::hash("__CLASS__"), utility::hash("const"), utility::hash("using"), utility::hash("enum")};

      return words.count(utility::hash(s)) == 1;
    }
@ -107,7 +107,10 @@ namespace chaiscript {
    Constant,
    Compiled,
    Const_Var_Decl,
-    Const_Assign_Decl
+    Const_Assign_Decl,
+    Using,
+    Enum,
+    Namespace_Block
  };

  enum class Operator_Precedence {
@ -128,7 +131,7 @@ namespace chaiscript {
  namespace {
    /// Helper lookup to get the name of each node type
    constexpr const char *ast_node_type_to_string(AST_Node_Type ast_node_type) noexcept {
-      constexpr const char *const ast_node_types[] = {"Id", "Fun_Call", "Unused_Return_Fun_Call", "Arg_List", "Equation", "Var_Decl", "Assign_Decl", "Array_Call", "Dot_Access", "Lambda", "Block", "Scopeless_Block", "Def", "While", "If", "For", "Ranged_For", "Inline_Array", "Inline_Map", "Return", "File", "Prefix", "Break", "Continue", "Map_Pair", "Value_Range", "Inline_Range", "Try", "Catch", "Finally", "Method", "Attr_Decl", "Logical_And", "Logical_Or", "Reference", "Switch", "Case", "Default", "Noop", "Class", "Binary", "Arg", "Global_Decl", "Constant", "Compiled", "Const_Var_Decl", "Const_Assign_Decl"};
+      constexpr const char *const ast_node_types[] = {"Id", "Fun_Call", "Unused_Return_Fun_Call", "Arg_List", "Equation", "Var_Decl", "Assign_Decl", "Array_Call", "Dot_Access", "Lambda", "Block", "Scopeless_Block", "Def", "While", "If", "For", "Ranged_For", "Inline_Array", "Inline_Map", "Return", "File", "Prefix", "Break", "Continue", "Map_Pair", "Value_Range", "Inline_Range", "Try", "Catch", "Finally", "Method", "Attr_Decl", "Logical_And", "Logical_Or", "Reference", "Switch", "Case", "Default", "Noop", "Class", "Binary", "Arg", "Global_Decl", "Constant", "Compiled", "Const_Var_Decl", "Const_Assign_Decl", "Using", "Enum", "Namespace_Block"};

      return ast_node_types[static_cast<int>(ast_node_type)];
    }
--- a/include/chaiscript/language/chaiscript_engine.hpp
+++ b/include/chaiscript/language/chaiscript_engine.hpp
@ -80,6 +80,7 @@ namespace chaiscript {
    std::map<std::string, std::function<Namespace &()>> m_namespace_generators;

    std::function<void(const std::string &)> m_print_handler = [](const std::string &) noexcept {};
+    std::function<std::string(const std::string &)> m_file_reader;

    /// Evaluates the given string in by parsing it and running the results through the evaluator
    Boxed_Value do_eval(const std::string &t_input, const std::string &t_filename = "__EVAL__", bool /* t_internal*/ = false) {
@ -145,6 +146,10 @@ namespace chaiscript {
        m_print_handler = t_handler;
      }), "set_print_handler");

+      m_engine.add(fun([this](const std::function<std::string(const std::string &)> &t_reader) {
+        m_file_reader = t_reader;
+      }), "set_file_reader");
+
      m_engine.add(fun([this]() { m_engine.dump_system(); }), "dump_system");
      m_engine.add(fun([this](const Boxed_Value &t_bv) { m_engine.dump_object(t_bv); }), "dump_object");
      m_engine.add(fun([this](const Boxed_Value &t_bv, const std::string &t_type) { return m_engine.is_type(t_bv, t_type); }), "is_type");
@ -194,10 +199,17 @@ namespace chaiscript {
      m_engine.add(fun([this](const Boxed_Value &t_bv, const std::string &t_name) { add_global(t_bv, t_name); }), "add_global");
      m_engine.add(fun([this](const Boxed_Value &t_bv, const std::string &t_name) { set_global(t_bv, t_name); }), "set_global");

-      // why this unused parameter to Namespace?
      m_engine.add(fun([this](const std::string &t_namespace_name) {
-                     register_namespace([](Namespace & /*space*/) noexcept {}, t_namespace_name);
-                     import(t_namespace_name);
+                     if (!m_namespace_generators.count(t_namespace_name)) {
+                       register_namespace([](Namespace & /*space*/) noexcept {}, t_namespace_name);
+                     }
+                     const auto sep_pos = t_namespace_name.find("::");
+                     const std::string root_name = (sep_pos != std::string::npos) ? t_namespace_name.substr(0, sep_pos) : t_namespace_name;
+                     if (!m_engine.get_scripting_objects().count(root_name)) {
+                       import(root_name);
+                     } else if (m_namespace_generators.count(root_name)) {
+                       nest_children(root_name, m_namespace_generators[root_name]());
+                     }
                   }),
                   "namespace");
      m_engine.add(fun([this](const std::string &t_namespace_name) { import(t_namespace_name); }), "import");
@ -242,7 +254,15 @@ namespace chaiscript {
    }

    /// Helper function for loading a file
-    static std::string load_file(const std::string &t_filename) {
+    std::string load_file(const std::string &t_filename) const {
+      if (m_file_reader) {
+        return m_file_reader(t_filename);
+      }
+
+      return load_file_default(t_filename);
+    }
+
+    static std::string load_file_default(const std::string &t_filename) {
      std::ifstream infile(t_filename.c_str(), std::ios::in | std::ios::ate | std::ios::binary);

      if (!infile.is_open()) {
@ -284,6 +304,12 @@ namespace chaiscript {
      m_print_handler = std::move(t_handler);
    }

+    /// \brief Set a custom handler for reading files, used by eval_file, use, and internal_eval_file
+    /// \param[in] t_reader Function to call with the filename, returning the file contents as a string
+    void set_file_reader(std::function<std::string(const std::string &)> t_reader) {
+      m_file_reader = std::move(t_reader);
+    }
+
    /// \brief Virtual destructor for ChaiScript
    virtual ~ChaiScript_Basic() = default;
     
@ -746,28 +772,59 @@ namespace chaiscript {
      if (m_engine.get_scripting_objects().count(t_namespace_name)) {
        throw std::runtime_error("Namespace: " + t_namespace_name + " was already defined");
      } else if (m_namespace_generators.count(t_namespace_name)) {
-        m_engine.add_global(var(std::ref(m_namespace_generators[t_namespace_name]())), t_namespace_name);
+        auto &ns = m_namespace_generators[t_namespace_name]();
+        nest_children(t_namespace_name, ns);
+        m_engine.add_global(var(std::ref(ns)), t_namespace_name);
      } else {
        throw std::runtime_error("No registered namespace: " + t_namespace_name);
      }
    }

    /// \brief Registers a namespace generator, which delays generation of the namespace until it is imported, saving memory if it is never
-    /// used. \param[in] t_namespace_generator Namespace generator function. \param[in] t_namespace_name Name of the Namespace function
-    /// being registered. \throw std::runtime_error In the case that the namespace name was already registered.
+    /// used. Supports C++-style nested names (e.g. "constants::si") for nested namespaces; parent namespaces are auto-registered if absent.
+    /// \param[in] t_namespace_generator Namespace generator function.
+    /// \param[in] t_namespace_name Name of the Namespace function being registered (may contain :: for nesting).
+    /// \throw std::runtime_error In the case that the namespace name was already registered.
    void register_namespace(const std::function<void(Namespace &)> &t_namespace_generator, const std::string &t_namespace_name) {
      chaiscript::detail::threading::unique_lock<chaiscript::detail::threading::recursive_mutex> l(m_use_mutex);

-      if (!m_namespace_generators.count(t_namespace_name)) {
-        // contain the namespace object memory within the m_namespace_generators map
-        m_namespace_generators.emplace(std::make_pair(t_namespace_name, [=, space = Namespace()]() mutable -> Namespace & {
-          t_namespace_generator(space);
-          return space;
-        }));
-      } else {
+      if (m_namespace_generators.count(t_namespace_name)) {
        throw std::runtime_error("Namespace: " + t_namespace_name + " was already registered.");
      }
+
+      m_namespace_generators.emplace(std::make_pair(t_namespace_name, [=, space = Namespace()]() mutable -> Namespace & {
+        t_namespace_generator(space);
+        return space;
+      }));
+
+      auto pos = t_namespace_name.rfind("::");
+      while (pos != std::string::npos) {
+        const std::string parent = t_namespace_name.substr(0, pos);
+        if (!m_namespace_generators.count(parent)) {
+          m_namespace_generators.emplace(std::make_pair(parent, [space = Namespace()]() mutable -> Namespace & {
+            return space;
+          }));
+        }
+        pos = parent.rfind("::");
+      }
    }
+
+  private:
+    void nest_children(const std::string &t_parent_name, Namespace &t_parent) {
+      const std::string prefix = t_parent_name + "::";
+      for (auto &[name, generator] : m_namespace_generators) {
+        if (name.size() > prefix.size() && name.compare(0, prefix.size(), prefix) == 0) {
+          const std::string remainder = name.substr(prefix.size());
+          if (remainder.find("::") == std::string::npos) {
+            auto &child_ns = generator();
+            nest_children(name, child_ns);
+            t_parent[remainder] = var(std::ref(child_ns));
+          }
+        }
+      }
+    }
+
+  public:
  };

 } // namespace chaiscript
--- a/include/chaiscript/language/chaiscript_eval.hpp
+++ b/include/chaiscript/language/chaiscript_eval.hpp
@ -16,6 +16,7 @@
 #include <map>
 #include <memory>
 #include <ostream>
+#include <algorithm>
 #include <stdexcept>
 #include <string>
 #include <vector>
@ -108,6 +109,169 @@ namespace chaiscript {
          return incoming;
        }
      }
+      class Strong_Typedef_Binary_Op final : public dispatch::Proxy_Function_Base {
+      public:
+        Strong_Typedef_Binary_Op(
+            std::string t_type_name,
+            std::string t_op_name,
+            Operators::Opers t_oper,
+            bool t_rewrap,
+            chaiscript::detail::Dispatch_Engine &t_engine)
+            : Proxy_Function_Base(
+                  {chaiscript::detail::Get_Type_Info<Boxed_Value>::get(),
+                   user_type<dispatch::Dynamic_Object>(),
+                   user_type<dispatch::Dynamic_Object>()},
+                  2)
+            , m_type_name(std::move(t_type_name))
+            , m_op_name(std::move(t_op_name))
+            , m_oper(t_oper)
+            , m_rewrap(t_rewrap)
+            , m_engine(t_engine) {
+        }
+
+        bool operator==(const Proxy_Function_Base &f) const noexcept override {
+          if (const auto *other = dynamic_cast<const Strong_Typedef_Binary_Op *>(&f)) {
+            return m_type_name == other->m_type_name && m_op_name == other->m_op_name;
+          }
+          return false;
+        }
+
+        bool call_match(const Function_Params &vals, const Type_Conversions_State &t_conversions) const noexcept override {
+          return vals.size() == 2
+              && type_matches(vals[0], t_conversions)
+              && type_matches(vals[1], t_conversions);
+        }
+
+      protected:
+        Boxed_Value do_call(const Function_Params &params, const Type_Conversions_State &t_conversions) const override {
+          if (!call_match(params, t_conversions)) {
+            throw chaiscript::exception::guard_error();
+          }
+
+          const auto &lhs = boxed_cast<const dispatch::Dynamic_Object &>(params[0], &t_conversions);
+          const auto &rhs = boxed_cast<const dispatch::Dynamic_Object &>(params[1], &t_conversions);
+          const auto lhs_val = lhs.get_attr("__value");
+          const auto rhs_val = rhs.get_attr("__value");
+
+          Boxed_Value result;
+          if (m_oper != Operators::Opers::invalid
+              && lhs_val.get_type_info().is_arithmetic()
+              && rhs_val.get_type_info().is_arithmetic()) {
+            result = Boxed_Number::do_oper(m_oper, lhs_val, rhs_val);
+          } else {
+            std::array<Boxed_Value, 2> underlying_params{lhs_val, rhs_val};
+            result = m_engine.call_function(m_op_name, m_loc, Function_Params(underlying_params), t_conversions);
+          }
+
+          if (m_rewrap) {
+            auto bv = Boxed_Value(dispatch::Dynamic_Object(m_type_name), true);
+            auto *obj = static_cast<dispatch::Dynamic_Object *>(bv.get_ptr());
+            obj->get_attr("__value") = result;
+            return bv;
+          }
+          return result;
+        }
+
+      private:
+        bool type_matches(const Boxed_Value &bv, const Type_Conversions_State &t_conversions) const noexcept {
+          if (!bv.get_type_info().bare_equal(user_type<dispatch::Dynamic_Object>())) {
+            return false;
+          }
+          try {
+            const auto &d = boxed_cast<const dispatch::Dynamic_Object &>(bv, &t_conversions);
+            return d.get_type_name() == m_type_name;
+          } catch (...) {
+            return false;
+          }
+        }
+
+        std::string m_type_name;
+        std::string m_op_name;
+        Operators::Opers m_oper;
+        bool m_rewrap;
+        chaiscript::detail::Dispatch_Engine &m_engine;
+        mutable std::atomic_uint_fast32_t m_loc{0};
+      };
+
+      class Strong_Typedef_Compound_Assign_Op final : public dispatch::Proxy_Function_Base {
+      public:
+        Strong_Typedef_Compound_Assign_Op(
+            std::string t_type_name,
+            std::string t_op_name,
+            Operators::Opers t_base_oper,
+            std::string t_base_op_name,
+            chaiscript::detail::Dispatch_Engine &t_engine)
+            : Proxy_Function_Base(
+                  {user_type<dispatch::Dynamic_Object>(),
+                   user_type<dispatch::Dynamic_Object>(),
+                   user_type<dispatch::Dynamic_Object>()},
+                  2)
+            , m_type_name(std::move(t_type_name))
+            , m_op_name(std::move(t_op_name))
+            , m_base_oper(t_base_oper)
+            , m_base_op_name(std::move(t_base_op_name))
+            , m_engine(t_engine) {
+        }
+
+        bool operator==(const Proxy_Function_Base &f) const noexcept override {
+          if (const auto *other = dynamic_cast<const Strong_Typedef_Compound_Assign_Op *>(&f)) {
+            return m_type_name == other->m_type_name && m_op_name == other->m_op_name;
+          }
+          return false;
+        }
+
+        bool call_match(const Function_Params &vals, const Type_Conversions_State &t_conversions) const noexcept override {
+          return vals.size() == 2
+              && type_matches(vals[0], t_conversions)
+              && type_matches(vals[1], t_conversions);
+        }
+
+      protected:
+        Boxed_Value do_call(const Function_Params &params, const Type_Conversions_State &t_conversions) const override {
+          if (!call_match(params, t_conversions)) {
+            throw chaiscript::exception::guard_error();
+          }
+
+          auto &lhs = boxed_cast<dispatch::Dynamic_Object &>(params[0], &t_conversions);
+          const auto &rhs = boxed_cast<const dispatch::Dynamic_Object &>(params[1], &t_conversions);
+          const auto lhs_val = lhs.get_attr("__value");
+          const auto rhs_val = rhs.get_attr("__value");
+
+          Boxed_Value result;
+          if (m_base_oper != Operators::Opers::invalid
+              && lhs_val.get_type_info().is_arithmetic()
+              && rhs_val.get_type_info().is_arithmetic()) {
+            result = Boxed_Number::do_oper(m_base_oper, lhs_val, rhs_val);
+          } else {
+            std::array<Boxed_Value, 2> underlying_params{lhs_val, rhs_val};
+            result = m_engine.call_function(m_base_op_name, m_loc, Function_Params(underlying_params), t_conversions);
+          }
+
+          lhs.get_attr("__value") = result;
+          return params[0];
+        }
+
+      private:
+        bool type_matches(const Boxed_Value &bv, const Type_Conversions_State &t_conversions) const noexcept {
+          if (!bv.get_type_info().bare_equal(user_type<dispatch::Dynamic_Object>())) {
+            return false;
+          }
+          try {
+            const auto &d = boxed_cast<const dispatch::Dynamic_Object &>(bv, &t_conversions);
+            return d.get_type_name() == m_type_name;
+          } catch (...) {
+            return false;
+          }
+        }
+
+        std::string m_type_name;
+        std::string m_op_name;
+        Operators::Opers m_base_oper;
+        std::string m_base_op_name;
+        chaiscript::detail::Dispatch_Engine &m_engine;
+        mutable std::atomic_uint_fast32_t m_loc{0};
+      };
+
    } // namespace detail

    template<typename T>
@ -792,40 +956,43 @@ namespace chaiscript {
        return false;
      }

-      Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
+      static std::shared_ptr<dispatch::Proxy_Function_Base> make_proxy_function(
+          const Def_AST_Node<T> &t_node, const chaiscript::detail::Dispatch_State &t_ss) {
        std::vector<std::string> t_param_names;
        size_t numparams = 0;

        dispatch::Param_Types param_types;

-        if ((this->children.size() > 1) && (this->children[1]->identifier == AST_Node_Type::Arg_List)) {
-          numparams = this->children[1]->children.size();
-          t_param_names = Arg_List_AST_Node<T>::get_arg_names(*this->children[1]);
-          param_types = Arg_List_AST_Node<T>::get_arg_types(*this->children[1], t_ss);
+        if ((t_node.children.size() > 1) && (t_node.children[1]->identifier == AST_Node_Type::Arg_List)) {
+          numparams = t_node.children[1]->children.size();
+          t_param_names = Arg_List_AST_Node<T>::get_arg_names(*t_node.children[1]);
+          param_types = Arg_List_AST_Node<T>::get_arg_types(*t_node.children[1], t_ss);
        }

        std::reference_wrapper<chaiscript::detail::Dispatch_Engine> engine(*t_ss);
        std::shared_ptr<dispatch::Proxy_Function_Base> guard;
-        if (m_guard_node) {
+        if (t_node.m_guard_node) {
          guard = dispatch::make_dynamic_proxy_function(
-              [engine, guardnode = m_guard_node, t_param_names](const Function_Params &t_params) {
+              [engine, guardnode = t_node.m_guard_node, t_param_names](const Function_Params &t_params) {
                return detail::eval_function(engine, *guardnode, t_param_names, t_params);
              },
              static_cast<int>(numparams),
-              m_guard_node);
+              t_node.m_guard_node);
        }

+        return dispatch::make_dynamic_proxy_function(
+            [engine, func_node = t_node.m_body_node, t_param_names](const Function_Params &t_params) {
+              return detail::eval_function(engine, *func_node, t_param_names, t_params);
+            },
+            static_cast<int>(numparams),
+            t_node.m_body_node,
+            param_types,
+            guard);
+      }
+
+      Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
        try {
-          const std::string &l_function_name = this->children[0]->text;
-          t_ss->add(dispatch::make_dynamic_proxy_function(
-                        [engine, func_node = m_body_node, t_param_names](const Function_Params &t_params) {
-                          return detail::eval_function(engine, *func_node, t_param_names, t_params);
-                        },
-                        static_cast<int>(numparams),
-                        m_body_node,
-                        param_types,
-                        guard),
-                    l_function_name);
+          t_ss->add(make_proxy_function(*this, t_ss), this->children[0]->text);
        } catch (const exception::name_conflict_error &e) {
          throw exception::eval_error("Function redefined '" + e.name() + "'");
        }
@ -891,6 +1058,269 @@ namespace chaiscript {
      }
    };

+    template<typename T>
+    struct Using_AST_Node final : AST_Node_Impl<T> {
+      Using_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children)
+          : AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Using, std::move(t_loc), std::move(t_children)) {
+        assert(this->children.size() == 2);
+      }
+
+      Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
+        const auto &new_type_name = this->children[0]->text;
+        const auto &base_type_name = this->children[1]->text;
+
+        const auto base_type = t_ss->get_type(base_type_name, true);
+
+        t_ss->add(user_type<dispatch::Dynamic_Object>(), new_type_name);
+
+        dispatch::Param_Types param_types(std::vector<std::pair<std::string, Type_Info>>{
+            {new_type_name, Type_Info()},
+            {base_type_name, base_type}});
+
+        auto ctor_body = dispatch::make_dynamic_proxy_function(
+            [](const Function_Params &t_params) -> Boxed_Value {
+              auto *obj = static_cast<dispatch::Dynamic_Object *>(t_params[0].get_ptr());
+              obj->get_attr("__value") = t_params[1];
+              return void_var();
+            },
+            2,
+            std::shared_ptr<AST_Node>(),
+            param_types);
+
+        try {
+          t_ss->add(std::make_shared<dispatch::detail::Dynamic_Object_Constructor>(new_type_name, ctor_body), new_type_name);
+        } catch (const exception::name_conflict_error &e) {
+          throw exception::eval_error("Type alias redefined '" + e.name() + "'");
+        }
+
+        dispatch::Param_Types to_underlying_param_types(std::vector<std::pair<std::string, Type_Info>>{
+            {new_type_name, user_type<dispatch::Dynamic_Object>()}});
+
+        auto to_underlying_body = dispatch::make_dynamic_proxy_function(
+            [](const Function_Params &t_params) -> Boxed_Value {
+              const auto *obj = static_cast<const dispatch::Dynamic_Object *>(t_params[0].get_const_ptr());
+              return obj->get_attr("__value");
+            },
+            1,
+            std::shared_ptr<AST_Node>(),
+            to_underlying_param_types);
+
+        t_ss->add(to_underlying_body, "to_underlying");
+
+        auto &engine = *t_ss;
+
+        struct Op_Entry {
+          const char *name;
+          Operators::Opers oper;
+          bool rewrap;
+        };
+
+        static constexpr Op_Entry ops[] = {
+            {"+", Operators::Opers::sum, true},
+            {"-", Operators::Opers::difference, true},
+            {"*", Operators::Opers::product, true},
+            {"/", Operators::Opers::quotient, true},
+            {"%", Operators::Opers::remainder, true},
+            {"<<", Operators::Opers::shift_left, true},
+            {">>", Operators::Opers::shift_right, true},
+            {"&", Operators::Opers::bitwise_and, true},
+            {"|", Operators::Opers::bitwise_or, true},
+            {"^", Operators::Opers::bitwise_xor, true},
+            {"<", Operators::Opers::less_than, false},
+            {">", Operators::Opers::greater_than, false},
+            {"<=", Operators::Opers::less_than_equal, false},
+            {">=", Operators::Opers::greater_than_equal, false},
+            {"==", Operators::Opers::equals, false},
+            {"!=", Operators::Opers::not_equal, false},
+        };
+
+        for (const auto &op : ops) {
+          t_ss->add(
+              chaiscript::make_shared<dispatch::Proxy_Function_Base, detail::Strong_Typedef_Binary_Op>(
+                  new_type_name, std::string(op.name), op.oper, op.rewrap, engine),
+              op.name);
+        }
+
+        struct Compound_Op_Entry {
+          const char *name;
+          Operators::Opers base_oper;
+          const char *base_op_name;
+        };
+
+        static constexpr Compound_Op_Entry compound_ops[] = {
+            {"+=", Operators::Opers::sum, "+"},
+            {"-=", Operators::Opers::difference, "-"},
+            {"*=", Operators::Opers::product, "*"},
+            {"/=", Operators::Opers::quotient, "/"},
+            {"%=", Operators::Opers::remainder, "%"},
+            {"<<=", Operators::Opers::shift_left, "<<"},
+            {">>=", Operators::Opers::shift_right, ">>"},
+            {"&=", Operators::Opers::bitwise_and, "&"},
+            {"|=", Operators::Opers::bitwise_or, "|"},
+            {"^=", Operators::Opers::bitwise_xor, "^"},
+        };
+
+        for (const auto &op : compound_ops) {
+          t_ss->add(
+              chaiscript::make_shared<dispatch::Proxy_Function_Base, detail::Strong_Typedef_Compound_Assign_Op>(
+                  new_type_name, std::string(op.name), op.base_oper, std::string(op.base_op_name), engine),
+              op.name);
+        }
+
+        return void_var();
+      }
+    };
+
+    template<typename T>
+    struct Enum_AST_Node final : AST_Node_Impl<T> {
+      Enum_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children)
+          : AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Enum, std::move(t_loc), std::move(t_children)) {
+      }
+
+      Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
+        const auto &enum_name = this->children[0]->text;
+        const auto &underlying_type_name = this->children[1]->text;
+        const auto underlying_ti = t_ss->get_type(underlying_type_name);
+
+        dispatch::Dynamic_Object container(enum_name);
+        std::vector<Boxed_Value> valid_values;
+
+        for (size_t i = 2; i < this->children.size(); i += 2) {
+          const auto &val_name = this->children[i]->text;
+          const auto val_bv = Boxed_Number(this->children[i + 1]->eval(t_ss)).get_as(underlying_ti).bv;
+          valid_values.push_back(val_bv);
+
+          dispatch::Dynamic_Object dobj(enum_name);
+          dobj.get_attr("value") = val_bv;
+          dobj.set_explicit(true);
+          container[val_name] = const_var(dobj);
+        }
+
+        auto shared_valid = std::make_shared<const std::vector<Boxed_Value>>(std::move(valid_values));
+
+        container[enum_name] = var(
+            fun([shared_valid, enum_name, underlying_ti](const Boxed_Number &t_val) -> Boxed_Value {
+              const auto converted = t_val.get_as(underlying_ti);
+              for (const auto &v : *shared_valid) {
+                if (Boxed_Number::equals(Boxed_Number(v), converted)) {
+                  dispatch::Dynamic_Object dobj(enum_name);
+                  dobj.get_attr("value") = converted.bv;
+                  dobj.set_explicit(true);
+                  return const_var(dobj);
+                }
+              }
+              throw exception::eval_error("Value is not valid for enum '" + enum_name + "'");
+            }));
+
+        t_ss->add_global_const(const_var(container), enum_name);
+
+        t_ss->add(
+            std::make_shared<dispatch::detail::Dynamic_Object_Function>(
+                enum_name,
+                fun([](const dispatch::Dynamic_Object &lhs, const dispatch::Dynamic_Object &rhs) {
+                  return Boxed_Number::equals(Boxed_Number(lhs.get_attr("value")), Boxed_Number(rhs.get_attr("value")));
+                })),
+            "==");
+
+        t_ss->add(
+            std::make_shared<dispatch::detail::Dynamic_Object_Function>(
+                enum_name,
+                fun([](const dispatch::Dynamic_Object &lhs, const dispatch::Dynamic_Object &rhs) {
+                  return !Boxed_Number::equals(Boxed_Number(lhs.get_attr("value")), Boxed_Number(rhs.get_attr("value")));
+                })),
+            "!=");
+
+        t_ss->add(
+            std::make_shared<dispatch::detail::Dynamic_Object_Function>(
+                enum_name,
+                fun([](const dispatch::Dynamic_Object &obj) { return obj.get_attr("value"); })),
+            "to_underlying");
+
+        return void_var();
+      }
+    };
+
+    template<typename T>
+    struct Namespace_Block_AST_Node final : AST_Node_Impl<T> {
+      Namespace_Block_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children)
+          : AST_Node_Impl<T>(std::move(t_ast_node_text), AST_Node_Type::Namespace_Block, std::move(t_loc), std::move(t_children)) {
+      }
+
+      Boxed_Value eval_internal(const chaiscript::detail::Dispatch_State &t_ss) const override {
+        const auto &ns_name = this->children[0]->text;
+
+        auto ns_name_bv = const_var(ns_name);
+        t_ss->call_function("namespace", m_ns_loc, Function_Params{ns_name_bv}, t_ss.conversions());
+
+        std::vector<std::string> parts;
+        {
+          std::string::size_type start = 0;
+          std::string::size_type pos = 0;
+          while ((pos = ns_name.find("::", start)) != std::string::npos) {
+            parts.push_back(ns_name.substr(start, pos - start));
+            start = pos + 2;
+          }
+          parts.push_back(ns_name.substr(start));
+        }
+
+        Boxed_Value ns_bv = t_ss.get_object(parts[0], m_root_loc);
+
+        for (size_t i = 1; i < parts.size(); ++i) {
+          auto &parent_ns = boxed_cast<dispatch::Dynamic_Object &>(ns_bv);
+          ns_bv = parent_ns.get_attr(parts[i]);
+        }
+
+        auto &target_ns = boxed_cast<dispatch::Dynamic_Object &>(ns_bv);
+
+        const auto process_statement = [&](const AST_Node_Impl<T> &stmt) {
+          if (stmt.identifier == AST_Node_Type::Def) {
+            const auto &def_node = static_cast<const Def_AST_Node<T> &>(stmt);
+            target_ns[def_node.children[0]->text] =
+                Boxed_Value(Def_AST_Node<T>::make_proxy_function(def_node, t_ss));
+          } else if (stmt.identifier == AST_Node_Type::Assign_Decl
+                     || stmt.identifier == AST_Node_Type::Const_Assign_Decl) {
+            const auto &var_name = stmt.children[0]->text;
+            auto value = detail::clone_if_necessary(stmt.children[1]->eval(t_ss), m_clone_loc, t_ss);
+            value.reset_return_value();
+            if (stmt.identifier == AST_Node_Type::Const_Assign_Decl) {
+              value.make_const();
+            }
+            target_ns[var_name] = std::move(value);
+          } else if (stmt.identifier == AST_Node_Type::Equation
+                     && !stmt.children.empty()
+                     && (stmt.children[0]->identifier == AST_Node_Type::Var_Decl
+                         || stmt.children[0]->identifier == AST_Node_Type::Const_Var_Decl)) {
+            const auto &var_name = stmt.children[0]->children[0]->text;
+            auto value = detail::clone_if_necessary(stmt.children[1]->eval(t_ss), m_clone_loc, t_ss);
+            value.reset_return_value();
+            target_ns[var_name] = std::move(value);
+          } else if (stmt.identifier == AST_Node_Type::Var_Decl) {
+            const auto &var_name = stmt.children[0]->text;
+            target_ns[var_name] = Boxed_Value();
+          } else {
+            throw exception::eval_error("Only declarations (def, var, auto, global) are allowed inside namespace blocks");
+          }
+        };
+
+        const auto &body = this->children[1];
+        if (body->identifier == AST_Node_Type::Block
+            || body->identifier == AST_Node_Type::Scopeless_Block) {
+          for (const auto &child : body->children) {
+            process_statement(*child);
+          }
+        } else {
+          process_statement(*body);
+        }
+
+        return void_var();
+      }
+
+    private:
+      mutable std::atomic_uint_fast32_t m_ns_loc = {0};
+      mutable std::atomic_uint_fast32_t m_root_loc = {0};
+      mutable std::atomic_uint_fast32_t m_clone_loc = {0};
+    };
+
    template<typename T>
    struct If_AST_Node final : AST_Node_Impl<T> {
      If_AST_Node(std::string t_ast_node_text, Parse_Location t_loc, std::vector<AST_Node_Impl_Ptr<T>> t_children)
--- a/include/chaiscript/language/chaiscript_parser.hpp
+++ b/include/chaiscript/language/chaiscript_parser.hpp
@ -1990,6 +1990,44 @@ namespace chaiscript {
      }

      /// Reads a class block from input
+      bool Namespace_Block() {
+        Depth_Counter dc{this};
+        const auto prev_stack_top = m_match_stack.size();
+        const auto prev_pos = m_position;
+
+        if (Keyword("namespace")) {
+          if (Id(true)) {
+            std::string ns_name = m_match_stack.back()->text;
+
+            while (Symbol("::")) {
+              if (!Id(true)) {
+                throw exception::eval_error("Incomplete namespace name after '::'",
+                                            File_Position(m_position.line, m_position.col),
+                                            *m_filename);
+              }
+              ns_name += "::" + m_match_stack.back()->text;
+              m_match_stack.pop_back();
+            }
+
+            m_match_stack.back() = make_node<eval::Id_AST_Node<Tracer>>(ns_name, prev_pos.line, prev_pos.col);
+
+            while (Eol()) {
+            }
+
+            if (Block()) {
+              build_match<eval::Namespace_Block_AST_Node<Tracer>>(prev_stack_top);
+              return true;
+            }
+          }
+
+          m_position = prev_pos;
+          while (prev_stack_top != m_match_stack.size()) {
+            m_match_stack.pop_back();
+          }
+        }
+        return false;
+      }
+
      bool Class(const bool t_class_allowed) {
        Depth_Counter dc{this};
        bool retval = false;
@ -2031,6 +2069,134 @@ namespace chaiscript {
        return retval;
      }

+      bool Using(const bool t_class_allowed) {
+        Depth_Counter dc{this};
+
+        const auto prev_stack_top = m_match_stack.size();
+
+        if (Keyword("using")) {
+          if (!t_class_allowed) {
+            throw exception::eval_error("Type alias definitions only allowed at top scope",
+                                        File_Position(m_position.line, m_position.col),
+                                        *m_filename);
+          }
+
+          if (!Id(true)) {
+            throw exception::eval_error("Missing type name in 'using' declaration",
+                                        File_Position(m_position.line, m_position.col),
+                                        *m_filename);
+          }
+
+          if (!Symbol("=", true)) {
+            throw exception::eval_error("Missing '=' in 'using' declaration",
+                                        File_Position(m_position.line, m_position.col),
+                                        *m_filename);
+          }
+
+          if (!Id(true)) {
+            throw exception::eval_error("Missing base type name in 'using' declaration",
+                                        File_Position(m_position.line, m_position.col),
+                                        *m_filename);
+          }
+
+          build_match<eval::Using_AST_Node<Tracer>>(prev_stack_top);
+          return true;
+        }
+
+        return false;
+      }
+
+      bool Enum(const bool t_allowed) {
+        Depth_Counter dc{this};
+        bool retval = false;
+
+        const auto prev_stack_top = m_match_stack.size();
+
+        if (Keyword("enum")) {
+          if (!Keyword("class") && !Keyword("struct")) {
+            throw exception::eval_error("Expected 'class' or 'struct' after 'enum' (only 'enum class'/'enum struct' is supported)",
+                                        File_Position(m_position.line, m_position.col),
+                                        *m_filename);
+          }
+
+          if (!t_allowed) {
+            throw exception::eval_error("Enum definitions only allowed at top scope",
+                                        File_Position(m_position.line, m_position.col),
+                                        *m_filename);
+          }
+
+          retval = true;
+
+          if (!Id(true)) {
+            throw exception::eval_error("Missing enum class name in definition", File_Position(m_position.line, m_position.col), *m_filename);
+          }
+
+          std::string underlying_type = "int";
+          if (Char(':')) {
+            if (!Id(false)) {
+              throw exception::eval_error("Expected underlying type after ':'",
+                                          File_Position(m_position.line, m_position.col),
+                                          *m_filename);
+            }
+            underlying_type = m_match_stack.back()->text;
+            m_match_stack.pop_back();
+          }
+
+          m_match_stack.push_back(
+              make_node<eval::Constant_AST_Node<Tracer>>(underlying_type, m_position.line, m_position.col, const_var(underlying_type)));
+
+          if (!Char('{')) {
+            throw exception::eval_error("Expected '{' after enum class declaration", File_Position(m_position.line, m_position.col), *m_filename);
+          }
+
+          int next_value = 0;
+
+          while (Eol()) {
+          }
+
+          if (!Char('}')) {
+            do {
+              while (Eol()) {
+              }
+
+              if (!Id(true)) {
+                throw exception::eval_error("Expected enum value name", File_Position(m_position.line, m_position.col), *m_filename);
+              }
+
+              if (Symbol("=")) {
+                if (!Num()) {
+                  throw exception::eval_error("Expected integer after '=' in enum definition",
+                                              File_Position(m_position.line, m_position.col),
+                                              *m_filename);
+                }
+                next_value = static_cast<int>(std::stoi(m_match_stack.back()->text));
+                m_match_stack.pop_back();
+              }
+
+              m_match_stack.push_back(
+                  make_node<eval::Constant_AST_Node<Tracer>>(std::to_string(next_value), m_position.line, m_position.col, const_var(next_value)));
+              ++next_value;
+
+              while (Eol()) {
+              }
+            } while (Char(',') && !Char('}'));
+
+            while (Eol()) {
+            }
+
+            if (!Char('}')) {
+              throw exception::eval_error("Expected '}' to close enum class definition",
+                                          File_Position(m_position.line, m_position.col),
+                                          *m_filename);
+            }
+          }
+
+          build_match<eval::Enum_AST_Node<Tracer>>(prev_stack_top);
+        }
+
+        return retval;
+      }
+
      /// Reads a while block from input
      bool While() {
        Depth_Counter dc{this};
@ -2379,7 +2545,7 @@ namespace chaiscript {
              }

              build_match<eval::Array_Call_AST_Node<Tracer>>(prev_stack_top);
-            } else if (Symbol(".")) {
+            } else if (Symbol(".") || Symbol("::")) {
              has_more = true;
              if (!(Id(true))) {
                throw exception::eval_error("Incomplete dot access fun call", File_Position(m_position.line, m_position.col), *m_filename);
@ -2776,7 +2942,7 @@ namespace chaiscript {

        while (has_more) {
          const auto start = m_position;
-          if (Def() || Try() || If() || While() || Class(t_class_allowed) || For() || Switch()) {
+          if (Def() || Try() || If() || While() || Namespace_Block() || Class(t_class_allowed) || Using(t_class_allowed) || Enum(t_class_allowed) || For() || Switch()) {
            if (!saw_eol) {
              throw exception::eval_error("Two function definitions missing line separator",
                                          File_Position(start.line, start.col),
--- a/readme.md
+++ b/readme.md
@ -91,6 +91,16 @@ the doxygen documentation in the build folder or see the website
 http://www.chaiscript.com.


+Grammar
+=======
+
+A formal EBNF grammar for ChaiScript is available in
+[grammar/chaiscript.ebnf](grammar/chaiscript.ebnf). To view it as a railroad
+diagram, paste the grammar into
+[mingodad's railroad diagram generator](https://mingodad.github.io/plgh/json2ebnf.html)
+or [bottlecaps.de/rr](https://www.bottlecaps.de/rr/ui).
+
+
 The shortest complete example possible follows:

 ```C++
--- a/releasenotes.md
+++ b/releasenotes.md
@ -4,6 +4,7 @@ Current Version: 6.1.1

 ### Changes since 6.1.0

+ * Add `set_file_reader` callback for custom file loading #116 — allows overriding how `eval_file` and `use` read files
 * Handle the returning of `&` to `*` types. This specifically comes up with `std::vector<int *>` and similar containers
 * Update CMake to use `LIBDIR` instead of `lib` #502 by @guoyunhe
 * Add documentation for installing ChaiScript with vcpkg #500 by @grdowns
--- a/unittests/compiled_tests.cpp
+++ b/unittests/compiled_tests.cpp
@ -1983,6 +1983,162 @@ TEST_CASE("eval_error with AST_Node_Trace call stack compiles in C++20") {
  }
 }

+TEST_CASE("Test set_file_reader from C++ land") {
+  chaiscript::ChaiScript chai;
+  chai.set_file_reader([](const std::string &) {
+    return std::string("var file_reader_test_val = 42");
+  });
+  chai.eval_file("nonexistent_file.chai");
+  CHECK(chai.eval<int>("file_reader_test_val") == 42);
+}
+
+TEST_CASE("Test set_file_reader from ChaiScript land") {
+  chaiscript::ChaiScript chai;
+  chai.set_file_reader([](const std::string &) {
+    return std::string("var from_custom_reader = true");
+  });
+  chai.eval("set_file_reader(fun(filename) { return \"var from_chai_reader = true\"; })");
+  chai.eval_file("any_file.chai");
+  CHECK(chai.eval<bool>("from_chai_reader") == true);
+}
+
+TEST_CASE("Test set_file_reader receives correct filename") {
+  chaiscript::ChaiScript chai;
+  std::string captured_filename;
+  chai.set_file_reader([&captured_filename](const std::string &t_filename) {
+    captured_filename = t_filename;
+    return std::string("var dummy = 1");
+  });
+  chai.eval_file("my_special_file.chai");
+  CHECK(captured_filename == "my_special_file.chai");
+}
+
+TEST_CASE("Test use with set_file_reader") {
+  chaiscript::ChaiScript chai;
+  chai.set_file_reader([](const std::string &) {
+    return std::string("var use_reader_val = 99");
+  });
+  chai.use("virtual_file.chai");
+  CHECK(chai.eval<int>("use_reader_val") == 99);
+}
+TEST_CASE("Nested namespaces via register_namespace with :: separator") {
+  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());
+
+  chai.register_namespace(
+      [](chaiscript::Namespace &si) {
+        si["mu_B"] = chaiscript::const_var(9.274);
+      },
+      "constants::si");
+
+  chai.register_namespace(
+      [](chaiscript::Namespace &mm) {
+        mm["mu_B"] = chaiscript::const_var(0.05788);
+      },
+      "constants::mm");
+
+  chai.import("constants");
+
+  CHECK(chai.eval<double>("constants.si.mu_B") == Approx(9.274));
+  CHECK(chai.eval<double>("constants.mm.mu_B") == Approx(0.05788));
+
+  // Scope resolution via :: works the same as . for access
+  CHECK(chai.eval<double>("constants::si::mu_B") == Approx(9.274));
+  CHECK(chai.eval<double>("constants::mm::mu_B") == Approx(0.05788));
+}
+
+TEST_CASE("Deeply nested namespaces via register_namespace") {
+  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());
+
+  chai.register_namespace(
+      [](chaiscript::Namespace &leaf) {
+        leaf["val"] = chaiscript::const_var(42);
+      },
+      "a::b::c");
+
+  chai.import("a");
+
+  CHECK(chai.eval<int>("a.b.c.val") == 42);
+  CHECK(chai.eval<int>("a::b::c::val") == 42);
+}
+
+TEST_CASE("Block namespace declaration with ::") {
+  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());
+
+  chai.eval(R"(
+    namespace math {
+      def square(x) { x * x }
+    }
+  )");
+
+  CHECK(chai.eval<int>("math::square(5)") == 25);
+  CHECK(chai.eval<int>("math.square(5)") == 25);
+}
+
+TEST_CASE("Nested block namespace declaration") {
+  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());
+
+  chai.eval(R"(
+    namespace physics::constants {
+      def speed_of_light() { return 299792458 }
+    }
+  )");
+
+  CHECK(chai.eval<int>("physics::constants::speed_of_light()") == 299792458);
+}
+
+TEST_CASE("Namespace block reopening") {
+  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());
+
+  chai.eval(R"(
+    namespace ns {
+      def foo() { return 1 }
+    }
+    namespace ns {
+      def bar() { return 2 }
+    }
+  )");
+
+  CHECK(chai.eval<int>("ns::foo()") == 1);
+  CHECK(chai.eval<int>("ns::bar()") == 2);
+}
+
+TEST_CASE("Namespace block with var declarations") {
+  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());
+
+  chai.eval(R"(
+    namespace config {
+      var pi = 3.14
+      var name = "hello"
+    }
+  )");
+
+  CHECK(chai.eval<double>("config::pi") == Approx(3.14));
+  CHECK(chai.eval<std::string>("config::name") == "hello");
+}
+
+TEST_CASE("Namespace block rejects non-declaration statements") {
+  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());
+
+  CHECK_THROWS_AS(chai.eval(R"(
+    namespace bad {
+      1 + 2
+    }
+  )"), chaiscript::exception::eval_error);
+
+  CHECK_THROWS_AS(chai.eval(R"(
+    namespace bad {
+      print("hello")
+    }
+  )"), chaiscript::exception::eval_error);
+
+  CHECK_THROWS_AS(chai.eval(R"(
+    var x = 5
+    namespace bad {
+      x = 10
+    }
+  )"), chaiscript::exception::eval_error);
+}
+
 TEST_CASE("C++ runtime_error thrown from registered function is catchable in ChaiScript") {
  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());

--- a/unittests/emscripten_exception_test.cpp
+++ b/unittests/emscripten_exception_test.cpp
@ -0,0 +1,72 @@
+// Test that validates exception propagation through the Emscripten eval wrapper.
+// Without proper exception support flags (-fwasm-exceptions) in the WASM build,
+// C++ exceptions would cause an abort instead of being catchable.
+
+#ifndef CHAISCRIPT_NO_THREADS
+#define CHAISCRIPT_NO_THREADS
+#endif
+
+#ifndef CHAISCRIPT_NO_DYNLOAD
+#define CHAISCRIPT_NO_DYNLOAD
+#endif
+
+#include <chaiscript/chaiscript.hpp>
+#include "../emscripten/chaiscript_eval.hpp"
+#include <cassert>
+#include <iostream>
+#include <stdexcept>
+#include <string>
+
+int main() {
+  // Verify that ChaiScript evaluation errors propagate as exceptions
+  // through the eval wrapper functions. In WASM builds without exception
+  // support, these would abort instead of throwing.
+
+  bool caught = false;
+
+  // Test 1: eval with undefined variable should throw
+  caught = false;
+  try {
+    chaiscript_eval("this_variable_does_not_exist");
+  } catch (const chaiscript::exception::eval_error &) {
+    caught = true;
+  }
+  assert(caught && "eval of undefined variable must throw eval_error");
+
+  // Test 2: evalString with a type mismatch should throw
+  caught = false;
+  try {
+    chaiscript_eval_string("1 + 2");
+  } catch (const chaiscript::exception::bad_boxed_cast &) {
+    caught = true;
+  }
+  assert(caught && "evalString with non-string result must throw bad_boxed_cast");
+
+  // Test 3: evalInt with invalid syntax should throw
+  caught = false;
+  try {
+    chaiscript_eval_int("def {}");
+  } catch (const chaiscript::exception::eval_error &) {
+    caught = true;
+  }
+  assert(caught && "evalInt with syntax error must throw eval_error");
+
+  // Test 4: eval with throw statement should propagate exception
+  caught = false;
+  try {
+    chaiscript_eval("throw(\"user exception\")");
+  } catch (const chaiscript::Boxed_Value &) {
+    caught = true;
+  } catch (...) {
+    caught = true;
+  }
+  assert(caught && "ChaiScript throw must propagate as an exception");
+
+  // Test 5: Verify normal operation still works after caught exceptions
+  chaiscript_eval("var post_exception_test = 100");
+  const int result = chaiscript_eval_int("post_exception_test");
+  assert(result == 100 && "normal eval must work after caught exceptions");
+
+  std::cout << "All emscripten exception tests passed.\n";
+  return 0;
+}
--- a/unittests/enum.chai
+++ b/unittests/enum.chai
@ -0,0 +1,110 @@
+// Basic enum class definition (default underlying type: int)
+enum class Color { Red, Green, Blue }
+
+// Access via :: syntax
+auto r = Color::Red
+auto g = Color::Green
+auto b = Color::Blue
+
+// Equality and inequality
+assert_true(Color::Red == Color::Red)
+assert_false(Color::Red == Color::Green)
+assert_true(Color::Red != Color::Green)
+assert_false(Color::Red != Color::Red)
+
+// Constructor from valid underlying value
+auto c = Color::Color(1)
+assert_true(c == Color::Green)
+
+// Constructor from invalid value throws
+try {
+  Color::Color(52)
+  assert_true(false)
+} catch(e) {
+  // expected
+}
+
+// Strong typing: function with typed parameter
+def takes_color(Color val) { val }
+takes_color(Color::Red)
+takes_color(Color::Green)
+takes_color(Color::Color(2))
+
+// Cannot pass int where Color is expected
+try {
+  takes_color(52)
+  assert_true(false)
+} catch(e) {
+  // expected: dispatch error
+}
+
+// to_underlying accessor
+assert_equal(0, Color::Red.to_underlying())
+assert_equal(1, Color::Green.to_underlying())
+assert_equal(2, Color::Blue.to_underlying())
+
+// Enum class with explicit values
+enum class Priority { Low = 10, Medium = 20, High = 30 }
+assert_equal(10, Priority::Low.to_underlying())
+assert_equal(20, Priority::Medium.to_underlying())
+assert_equal(30, Priority::High.to_underlying())
+
+auto p = Priority::Priority(20)
+assert_true(p == Priority::Medium)
+
+// Mixed auto and explicit values
+enum class Status { Pending, Active = 5, Done }
+assert_equal(0, Status::Pending.to_underlying())
+assert_equal(5, Status::Active.to_underlying())
+assert_equal(6, Status::Done.to_underlying())
+
+// Switch on enum values
+var result = ""
+switch(Color::Green) {
+  case (Color::Red) {
+    result = "red"
+    break
+  }
+  case (Color::Green) {
+    result = "green"
+    break
+  }
+  case (Color::Blue) {
+    result = "blue"
+    break
+  }
+}
+assert_equal("green", result)
+
+// Switch on enum with explicit values
+var prio_result = ""
+switch(Priority::High) {
+  case (Priority::Low) {
+    prio_result = "low"
+    break
+  }
+  case (Priority::Medium) {
+    prio_result = "medium"
+    break
+  }
+  case (Priority::High) {
+    prio_result = "high"
+    break
+  }
+}
+assert_equal("high", prio_result)
+
+// Enum class with explicit underlying type
+enum class Flags : char { Read = 1, Write = 2, Execute = 4 }
+assert_equal(1, Flags::Read.to_underlying())
+assert_equal(2, Flags::Write.to_underlying())
+assert_equal(4, Flags::Execute.to_underlying())
+
+auto f = Flags::Flags(2)
+assert_true(f == Flags::Write)
+
+// enum struct syntax (equivalent to enum class, like C++)
+enum struct Direction { North, East, South, West }
+assert_equal(0, Direction::North.to_underlying())
+assert_equal(3, Direction::West.to_underlying())
+assert_true(Direction::East != Direction::South)
--- a/unittests/grammar_constructs.chai
+++ b/unittests/grammar_constructs.chai
@ -0,0 +1,219 @@
+// Regression test: exercises grammar constructs documented in grammar/chaiscript.ebnf
+
+// --- Variable declarations ---
+var a = 1
+auto b = 2
+global c = 3
+const d = 42
+
+assert_equal(1, a)
+assert_equal(2, b)
+assert_equal(3, c)
+assert_equal(42, d)
+
+// --- Reference variables ---
+var orig = 10
+var &ref = orig
+ref = 20
+assert_equal(20, orig)
+
+// --- Numeric literals ---
+assert_equal(255, 0xFF)
+assert_equal(255, 0xff)
+assert_equal(5, 0b101)
+assert_equal(42, 42)
+assert_equal(3.14, 3.14)
+
+// --- String interpolation ---
+var name = "world"
+assert_equal("hello world", "hello ${name}")
+
+// --- Escape sequences ---
+assert_equal("\n", "\n")
+assert_equal("\t", "\t")
+
+// --- Single-quoted char ---
+assert_equal('A', 'A')
+
+// --- Operators and precedence ---
+assert_equal(7, 1 + 2 * 3)
+assert_equal(true, 5 > 3 && 2 < 4)
+assert_equal(true, false || true)
+assert_equal(6, 3 << 1)
+assert_equal(1, 3 >> 1)
+assert_equal(5, 7 & 5)
+assert_equal(7, 5 | 3)
+assert_equal(6, 5 ^ 3)
+assert_equal(-1, ~0)
+
+// --- Ternary operator ---
+assert_equal("yes", true ? "yes" : "no")
+assert_equal("no", false ? "yes" : "no")
+
+// --- Prefix operators ---
+var x = 5
++x
+assert_equal(6, x)
+--x
+assert_equal(5, x)
+assert_equal(true, !false)
+
+// --- Assignment operators ---
+var v = 10
+v += 5; assert_equal(15, v)
+v -= 3; assert_equal(12, v)
+v *= 2; assert_equal(24, v)
+v /= 4; assert_equal(6, v)
+v %= 4; assert_equal(2, v)
+v <<= 2; assert_equal(8, v)
+v >>= 1; assert_equal(4, v)
+v |= 3; assert_equal(7, v)
+v &= 5; assert_equal(5, v)
+v ^= 3; assert_equal(6, v)
+
+// --- Lambda ---
+var add = fun(a, b) { a + b }
+assert_equal(5, add(2, 3))
+
+// --- Lambda with capture ---
+var captured = 100
+var get_captured = fun[captured]() { captured }
+assert_equal(100, get_captured())
+
+// --- Function definition ---
+def multiply(a, b) { a * b }
+assert_equal(12, multiply(3, 4))
+
+// --- Guard condition on function ---
+def abs_val(x) : x >= 0 { x }
+def abs_val(x) : x < 0 { -x }
+assert_equal(5, abs_val(5))
+assert_equal(5, abs_val(-5))
+
+// --- Class definition ---
+class Animal
+{
+  attr sound
+  def Animal(s) { this.sound = s }
+  def speak() { this.sound }
+}
+
+var dog = Animal("woof")
+assert_equal("woof", dog.speak())
+
+// --- Class with inheritance ---
+class Puppy : Animal
+{
+  attr name
+  def Puppy(n, s) { this.name = n; this.sound = s }
+  def greet() { to_string(this.name) + " says " + to_string(this.speak()) }
+}
+
+var p = Puppy("Rex", "yip")
+assert_equal("Rex says yip", p.greet())
+
+// --- Control flow: if/else ---
+var result = ""
+if (true) { result = "yes" } else { result = "no" }
+assert_equal("yes", result)
+
+// --- Control flow: while ---
+var counter = 0
+while (counter < 3) { ++counter }
+assert_equal(3, counter)
+
+// --- Control flow: for ---
+var sum = 0
+for (var i = 0; i < 5; ++i) { sum += i }
+assert_equal(10, sum)
+
+// --- Control flow: ranged for ---
+var items = [10, 20, 30]
+var total = 0
+for (item : items) { total += item }
+assert_equal(60, total)
+
+// --- Switch/case ---
+def classify(n) {
+  var label = ""
+  switch (n) {
+    case (1) { label = "one"; break }
+    case (2) { label = "two"; break }
+    default { label = "other" }
+  }
+  return label
+}
+assert_equal("one", classify(1))
+assert_equal("two", classify(2))
+assert_equal("other", classify(99))
+
+// --- Try/catch/finally ---
+var caught = false
+var finalized = false
+try {
+  throw("oops")
+} catch (e) {
+  caught = true
+} finally {
+  finalized = true
+}
+assert_true(caught)
+assert_true(finalized)
+
+// --- Inline containers ---
+var vec = [1, 2, 3]
+assert_equal(3, vec.size())
+
+var m = ["a": 1, "b": 2]
+assert_equal(1, m["a"])
+
+var r = [1, 2, 3, 4, 5]
+assert_equal(5, r.size())
+
+// --- Dot access chaining ---
+assert_equal(3, [1, 2, 3].size())
+
+// --- Array access ---
+var arr = [10, 20, 30]
+assert_equal(20, arr[1])
+
+// --- Backtick identifier ---
+var `my var` = 42
+assert_equal(42, `my var`)
+
+// --- Special identifiers ---
+assert_equal(true, true)
+assert_equal(false, false)
+
+// --- Nested block ---
+var block_result = 0
+{ block_result = 42 }
+assert_equal(42, block_result)
+
+// --- Break and continue ---
+var break_sum = 0
+for (var i = 0; i < 10; ++i) {
+  if (i == 5) { break }
+  break_sum += i
+}
+assert_equal(10, break_sum)
+
+var cont_sum = 0
+for (var i = 0; i < 5; ++i) {
+  if (i == 2) { continue }
+  cont_sum += i
+}
+assert_equal(8, cont_sum)
+
+// --- Return from function ---
+def early_return(n) {
+  if (n > 0) { return "positive" }
+  return "non-positive"
+}
+assert_equal("positive", early_return(1))
+assert_equal("non-positive", early_return(-1))
+
+// --- Colon assignment ---
+var ca = 0
+ca := 99
+assert_equal(99, ca)
--- a/unittests/nested_namespaces.chai
+++ b/unittests/nested_namespaces.chai
@ -0,0 +1,55 @@
+// Test C++-style block namespace declarations
+namespace constants::si {
+  def mu_B() { return 1.0 }
+}
+
+namespace constants::mm {
+  def mu_B() { return 2.0 }
+}
+
+assert_equal(1.0, constants::si::mu_B())
+assert_equal(2.0, constants::mm::mu_B())
+
+// Test deeper nesting with block syntax
+namespace a::b::c {
+  def val() { return 42 }
+}
+
+assert_equal(42, a::b::c::val())
+
+// Test reopening a namespace to add more members
+namespace math {
+  def square(x) { x * x }
+}
+
+namespace math::trig {
+  def double_angle(x) { 2.0 * x }
+}
+
+assert_equal(16, math::square(4))
+assert_equal(6.0, math::trig::double_angle(3.0))
+
+// Test reopening a namespace (C++ allows this)
+namespace math {
+  def cube(x) { x * x * x }
+}
+
+assert_equal(27, math::cube(3))
+
+// Test that :: scope resolution works the same as . for access
+assert_equal(16, math.square(4))
+assert_equal(6.0, math.trig.double_angle(3.0))
+
+// Test namespace with var declarations
+namespace config {
+  var pi = 3.14159
+  var name = "test"
+}
+
+assert_equal(3.14159, config::pi)
+assert_equal("test", config::name)
+
+// Test function-call style still works
+namespace("compat")
+compat.legacy = 99
+assert_equal(99, compat::legacy)
--- a/unittests/strong_typedef.chai
+++ b/unittests/strong_typedef.chai
@ -0,0 +1,200 @@
+// Strong typedef: using Type = int creates a distinct type
+using Meters = int
+
+def measure(Meters m) {
+  return m
+}
+
+// Constructing a strong typedef value should work
+var m = Meters(42)
+
+// Calling with the typedef'd value should succeed
+measure(m)
+
+// Calling with a plain int should fail (strong typedef)
+try {
+  measure(42)
+  assert_equal(true, false)
+} catch(e) {
+  // Expected: type mismatch because int is not Meters
+}
+
+// Multiple strong typedefs from the same base type should be distinct
+using Seconds = int
+
+def wait(Seconds s) {
+  return s
+}
+
+var s = Seconds(10)
+wait(s)
+
+// Meters and Seconds should not be interchangeable
+try {
+  wait(m)
+  assert_equal(true, false)
+} catch(e) {
+  // Expected: Meters is not Seconds
+}
+
+try {
+  measure(s)
+  assert_equal(true, false)
+} catch(e) {
+  // Expected: Seconds is not Meters
+}
+
+// to_underlying should return the base value
+assert_equal(to_underlying(m), 42)
+assert_equal(to_underlying(s), 10)
+
+// to_underlying result should be a plain value, not a strong typedef
+def takes_int(int i) {
+  return i
+}
+assert_equal(takes_int(to_underlying(m)), 42)
+
+// --- Arithmetic operators: strongly typed ---
+var m2 = Meters(8)
+var m_sum = m + m2
+assert_equal(to_underlying(m_sum), 50)
+measure(m_sum)
+
+var m_diff = m - m2
+assert_equal(to_underlying(m_diff), 34)
+
+var m_prod = Meters(3) * Meters(4)
+assert_equal(to_underlying(m_prod), 12)
+
+var m_quot = Meters(20) / Meters(5)
+assert_equal(to_underlying(m_quot), 4)
+
+var m_rem = Meters(17) % Meters(5)
+assert_equal(to_underlying(m_rem), 2)
+
+// Arithmetic result is strongly typed, not plain int
+try {
+  takes_int(m_sum)
+  assert_equal(true, false)
+} catch(e) {
+  // Expected: m_sum is Meters, not int
+}
+
+// --- Comparison operators ---
+assert_equal(Meters(5) == Meters(5), true)
+assert_equal(Meters(5) != Meters(3), true)
+assert_equal(Meters(3) < Meters(5), true)
+assert_equal(Meters(5) > Meters(3), true)
+assert_equal(Meters(5) <= Meters(5), true)
+assert_equal(Meters(3) >= Meters(3), true)
+assert_equal(Meters(3) >= Meters(5), false)
+
+// --- Bitwise and shift operators ---
+assert_equal(to_underlying(Meters(6) & Meters(3)), 2)
+assert_equal(to_underlying(Meters(6) | Meters(3)), 7)
+assert_equal(to_underlying(Meters(6) ^ Meters(3)), 5)
+assert_equal(to_underlying(Meters(5) << Meters(2)), 20)
+assert_equal(to_underlying(Meters(12) >> Meters(1)), 6)
+
+// Bitwise results are strongly typed
+try {
+  takes_int(Meters(6) & Meters(3))
+  assert_equal(true, false)
+} catch(e) {
+  // Expected: result is Meters, not int
+}
+
+// --- Strong typedef over string ---
+using StrongString = string
+
+var ss1 = StrongString("hello")
+var ss2 = StrongString(" world")
+var ss_cat = ss1 + ss2
+assert_equal(to_underlying(ss_cat), "hello world")
+
+// StrongString + StrongString -> StrongString (strongly typed)
+def takes_strong_string(StrongString ss) {
+  return ss
+}
+takes_strong_string(ss_cat)
+
+// Operators not supported by the underlying type error at call time
+try {
+  var bad = ss1 * ss2
+  assert_equal(true, false)
+} catch(e) {
+  // Expected: underlying string has no * operator
+}
+try {
+  var bad = ss1 - ss2
+  assert_equal(true, false)
+} catch(e) {
+  // Expected: underlying string has no - operator
+}
+try {
+  var bad = ss1 / ss2
+  assert_equal(true, false)
+} catch(e) {
+  // Expected: underlying string has no / operator
+}
+try {
+  var bad = ss1 % ss2
+  assert_equal(true, false)
+} catch(e) {
+  // Expected: underlying string has no % operator
+}
+
+// Comparison on StrongString
+assert_equal(StrongString("abc") < StrongString("def"), true)
+assert_equal(StrongString("abc") == StrongString("abc"), true)
+assert_equal(StrongString("abc") != StrongString("def"), true)
+assert_equal(StrongString("def") > StrongString("abc"), true)
+assert_equal(StrongString("abc") <= StrongString("abc"), true)
+assert_equal(StrongString("def") >= StrongString("abc"), true)
+
+// --- User-defined extensions on strong typedefs ---
+def first_char(StrongString ss) {
+  return to_string(to_underlying(ss)[0])
+}
+assert_equal(first_char(StrongString("hello")), "h")
+
+def double_meters(Meters m) {
+  return Meters(to_underlying(m) * 2)
+}
+assert_equal(to_underlying(double_meters(Meters(21))), 42)
+
+// User-defined operator extension
+def `[]`(StrongString ss, int offset) {
+  return to_string(to_underlying(ss)[offset])
+}
+assert_equal(StrongString("hello")[1], "e")
+
+// --- Compound assignment operators ---
+var m3 = Meters(10)
+m3 += Meters(5)
+assert_equal(to_underlying(m3), 15)
+measure(m3)
+
+m3 -= Meters(3)
+assert_equal(to_underlying(m3), 12)
+
+m3 *= Meters(2)
+assert_equal(to_underlying(m3), 24)
+
+m3 /= Meters(4)
+assert_equal(to_underlying(m3), 6)
+
+m3 %= Meters(4)
+assert_equal(to_underlying(m3), 2)
+
+// Compound assignment result is still the strong typedef
+var m4 = Meters(10)
+m4 += Meters(5)
+assert_equal(to_underlying(m4), 15)
+measure(m4)
+
+// Compound assignment on StrongString
+var ss3 = StrongString("hello")
+ss3 += StrongString(" world")
+assert_equal(to_underlying(ss3), "hello world")
+takes_strong_string(ss3)