closures/anon

README.md

@@ -41,4 +41,14 @@ elseif otherExpression() then
 else
 	// final thing
 end
+
+// Table order is preserved, unlike Lua
+table = {
+	anything = "foo",
+	123 = "arg"
+}
+echo table["anything"] // outputs foo
+echo table.anything // outputs foo
+table.rawr = "mega"
+table["mega"] = "rawr"
 ```

types/ast.go

@@ -91,9 +91,10 @@ func (a AssignStmt) String() string {
 
 // FunctionStmt represents a function declaration
 type FunctionStmt struct {
-	Name   Token
+	Name       Token
-	Params []Token
+	Params     []Token
-	Body   []Statement
+	IsVariadic bool
+	Body       []Statement
 }
 
 func (f FunctionStmt) statementNode() {}
@@ -105,9 +106,46 @@ func (f FunctionStmt) String() string {
 		}
 		params += param.Lexeme
 	}
+
+	if f.IsVariadic {
+		if len(f.Params) > 0 {
+			params += ", ..."
+		} else {
+			params += "..."
+		}
+	}
+
 	return fmt.Sprintf("fn %s(%s) ... end", f.Name.Lexeme, params)
 }
 
+// FunctionStmt represents a function expression (anonymous function)
+type FunctionExpr struct {
+	Params     []Token
+	IsVariadic bool
+	Body       []Statement
+}
+
+func (f FunctionExpr) expressionNode() {}
+func (f FunctionExpr) String() string {
+	params := ""
+	for i, param := range f.Params {
+		if i > 0 {
+			params += ", "
+		}
+		params += param.Lexeme
+	}
+
+	if f.IsVariadic {
+		if len(f.Params) > 0 {
+			params += ", ..."
+		} else {
+			params += "..."
+		}
+	}
+
+	return fmt.Sprintf("fn(%s) ... end", params)
+}
+
 // ReturnStmt represents a return statement
 type ReturnStmt struct {
 	Keyword Token

types/bytecode.go

@@ -34,6 +34,10 @@ const (
 	OP_JUMP_IF_FALSE
 	OP_CALL
 	OP_RETURN
+	OP_CLOSURE
+	OP_GET_UPVALUE
+	OP_SET_UPVALUE
+	OP_CLOSE_UPVALUE
 )
 
 // String returns the string representation of an OpCode
@@ -44,7 +48,8 @@ func (op OpCode) String() string {
 		"OP_SET_GLOBAL", "OP_EQUAL", "OP_GREATER", "OP_LESS",
 		"OP_ADD", "OP_SUBTRACT", "OP_MULTIPLY", "OP_DIVIDE",
 		"OP_NOT", "OP_NEGATE", "OP_PRINT", "OP_JUMP",
-		"OP_JUMP_IF_FALSE", "OP_CALL", "OP_RETURN",
+		"OP_JUMP_IF_FALSE", "OP_CALL", "OP_RETURN", "OP_CLOSURE",
+		"OP_GET_UPVALUE", "OP_SET_UPVALUE", "OP_CLOSE_UPVALUE",
 	}
 	return names[op]
 }
@@ -66,11 +71,18 @@ type Chunk struct {
 type Function struct {
 	Name         string
 	Arity        int
+	IsVariadic   bool
 	Chunk        *Chunk
+	Upvalues     []Upvalue
 	LocalCount   int
 	UpvalueCount int
 }
 
+type Closure struct {
+	Function *Function
+	Upvalues []*Upvalue
+}
+
 // Environment represents a variable scope
 type Environment struct {
 	Values    map[string]Value
@@ -84,3 +96,9 @@ func NewEnvironment(enclosing *Environment) *Environment {
 		Enclosing: enclosing,
 	}
 }
+
+// Upvalue support for closures
+type Upvalue struct {
+	Index   uint8
+	IsLocal bool
+}

types/token.go

@@ -55,6 +55,7 @@ const (
 	LEFT_PAREN  // (
 	RIGHT_PAREN // )
 	COMMA       // ,
+	ELLIPSIS    // ...
 )
 
 // String returns the string representation of the token type
@@ -96,4 +97,5 @@ var tokenNames = [...]string{
 	LEFT_PAREN:    "LEFT_PAREN",
 	RIGHT_PAREN:   "RIGHT_PAREN",
 	COMMA:         "COMMA",
+	ELLIPSIS:      "ELLIPSIS",
 }

types/value.go

@@ -12,6 +12,7 @@ const (
 	STRING_TYPE
 	FUNCTION_TYPE
 	TABLE_TYPE
+	CLOSURE_TYPE
 )
 
 // Value interface represents any value in the language at runtime
@@ -104,3 +105,18 @@ func (t TableValue) Type() ValueType {
 func (t TableValue) String() string {
 	return fmt.Sprintf("<table: %p>", &t)
 }
+
+type ClosureValue struct {
+	Closure *Closure
+}
+
+func (c ClosureValue) Type() ValueType {
+	return CLOSURE_TYPE
+}
+
+func (c ClosureValue) String() string {
+	if c.Closure.Function.Name == "" {
+		return "<anonymous function>"
+	}
+	return fmt.Sprintf("<function %s>", c.Closure.Function.Name)
+}