we in era3 boys; overhauled expression system, and variables are now in maps

core/all_test.go

@@ -8,107 +8,66 @@ import (
 type AllTestCase struct {
 	src           string
 	expectedStack []Value
+	expectedScope []map[string]Value
 }
 
 func GetAllTestCases() map[string]AllTestCase {
 	return map[string]AllTestCase{
 		"constant_number": {
 			"a := 1",
-			[]Value{
+			[]Value{&IntegerValue{new(big.Int).SetInt64(1)}},
-				&VariableValue{
+			[]map[string]Value{
-					"a",
+				{"a": &IntegerValue{new(big.Int).SetInt64(1)}},
-					&IntegerValue{new(big.Int).SetInt64(1)},
-					0,
-				},
 			},
 		},
 		"func": {
-			"fn sum(a: int, b: int) -> int {\n\treturn a + b\n}\n_ = sum(1, 2)",
+			"fn sum(a: int, b: int) -> int {\n\treturn a + b\n}\nres := sum(1, 2)",
-			[]Value{
+			[]Value{&IntegerValue{new(big.Int).SetInt64(3)}},
-				&VariableValue{
+			[]map[string]Value{},
-					"sum",
-					&FunctionValue{
-						Name: "sum",
-						Params: []FunctionParameter{
-							{
-								"a",
-								&IntegerSignature{},
-							},
-							{
-								"b",
-								&IntegerSignature{},
-							},
-						},
-						Chunk: &Chunk{
-							Bytecode: []Bytecode{
-								InstructionDescend,
-								InstructionGetLocal, 0,
-								InstructionGetLocal, 1,
-								InstructionAddInt,
-								InstructionReturn,
-								InstructionAscend,
-							},
-							Constants: []Value{&StringValue{"a"}, &StringValue{"b"}},
-						},
-					},
-					0,
-				},
-			},
 		},
 		"list": {
-			"a := [1.0, 2.0]",
+			"a := [1.0, 2.0]\n{}",
-			[]Value{
+			[]Value{&NilValue{}},
-				&VariableValue{
+			[]map[string]Value{
-					"a",
+				{"a": &ListValue{
-					&ListValue{
+					[]Value{
-						[]Value{
+						&FloatValue{1},
-							&FloatValue{1},
+						&FloatValue{2},
-							&FloatValue{2},
-						},
 					},
-					0,
+				}},
-				},
 			},
 		},
 		"constant_list_concat": {
-			"a := [1, 2] + [3]",
+			"a := [1, 2] + [3]\n{}",
-			[]Value{
+			[]Value{&NilValue{}},
-				&VariableValue{
+			[]map[string]Value{
-					"a",
+				{"a": &ListValue{
-					&ListValue{
+					[]Value{
-						[]Value{
+						&IntegerValue{big.NewInt(1)},
-							&IntegerValue{big.NewInt(1)},
+						&IntegerValue{big.NewInt(2)},
-							&IntegerValue{big.NewInt(2)},
+						&IntegerValue{big.NewInt(3)},
-							&IntegerValue{big.NewInt(3)},
-						},
 					},
-					0,
+				}},
-				},
 			},
 		},
 		"list_concat": {
-			"a := [1.0, 2.0]\nb := a + [3.0]",
+			"a := [1.0, 2.0]\nb := a + [3.0]\nnil",
-			[]Value{
+			[]Value{&NilValue{}},
-				&VariableValue{
+			[]map[string]Value{
-					"a",
+				{
-					&ListValue{
+					"a": &ListValue{
 						[]Value{
 							&FloatValue{1},
 							&FloatValue{2},
 						},
 					},
-					0,
+					"b": &ListValue{
-				},
-				&VariableValue{
-					"b",
-					&ListValue{
 						[]Value{
 							&FloatValue{1},
 							&FloatValue{2},
 							&FloatValue{3},
 						},
 					},
-					0,
 				},
 			},
 		},
@@ -160,7 +119,13 @@ func TestAll(t *testing.T) {
 			}
 
 			t.Log("Comparing stacks")
+
 			CompareStacks(t, tc.expectedStack, vm.stack)
+
+			// expected scope == nil => we don't care
+			if tc.expectedScope != nil {
+				CompareScope(t, tc.expectedScope, vm.scope)
+			}
 		})
 	}
 }

core/compiler.go

@@ -18,6 +18,9 @@ type Compiler struct {
 	source   []rune
 	Warnings []CompilerError
 
+	// optimize Whether to attempt some optimization of the emitted bytecode
+	optimize bool
+
 	stack *Stack[LocalVariable]
 }
 
@@ -129,6 +132,7 @@ func NewCompiler(source []rune) *Compiler {
 		nil,
 		source,
 		[]CompilerError{},
+		false,
 		NewStack[LocalVariable](256),
 	}
 
@@ -169,10 +173,14 @@ func (c *Compiler) Compile(p *Program) error {
 		}
 	}
 
-	for _, s := range p.Block.statements {
+	for i, s := range p.Block.statements {
 		if err := c.compile(s); err != nil {
 			return err
 		}
+
+		if i != len(p.Block.statements)-1 {
+			c.add(InstructionPop)
+		}
 	}
 
 	c.fileStack.Pop()
@@ -205,7 +213,7 @@ func (c *Compiler) compile(tree Node) error {
 
 		if len(l.items) == 0 {
 			c.add(InstructionNewList)
-		} else if c.isTreeConstant(l) {
+		} else if c.optimize && c.isTreeConstant(l) {
 			v, err := c.compute(l)
 			if err != nil {
 				panic(err) // this shouldn't happen
@@ -234,7 +242,7 @@ func (c *Compiler) compile(tree Node) error {
 		}
 
 	case UnaryNodeType:
-		if c.isTreeConstant(tree.(*UnaryNode).value) {
+		if c.optimize && c.isTreeConstant(tree.(*UnaryNode).value) {
 			v, err := c.compute(tree)
 			if err != nil {
 				return err
@@ -277,12 +285,21 @@ func (c *Compiler) compile(tree Node) error {
 		c.add(InstructionNil)
 
 	case BlockNodeType:
+		if len(tree.(*BlockNode).statements) == 0 {
+			c.add(InstructionNil)
+			return nil
+		}
+
 		c.addDescend()
-		for _, n := range tree.(*BlockNode).statements {
+		for i, n := range tree.(*BlockNode).statements {
 			err := c.compile(n)
 			if err != nil {
 				return err
 			}
+
+			if i != len(tree.(*BlockNode).statements)-1 {
+				c.add(InstructionPop)
+			}
 		}
 		c.addAscend()
 
@@ -298,7 +315,7 @@ func (c *Compiler) compile(tree Node) error {
 			return c.error(fmt.Sprintf("conditional requires boolean; cannot use non-boolean type %s", sig), n.condition)
 		}
 
-		if c.isTreeConstant(n.condition) {
+		if c.optimize && c.isTreeConstant(n.condition) {
 			v, err := c.compute(n.condition)
 			if err != nil {
 				return err
@@ -336,13 +353,10 @@ func (c *Compiler) compile(tree Node) error {
 		}
 
 		// we store the position of the jump over the else code here
-		var jumpOverElse Pos
+		// this would jump over the else/otherwise block in the code
-		if n.otherwise != nil {
+		c.add(InstructionJump)
-			// this would jump over the else/otherwise block in the code
+		jumpOverElse := c.ip
-			c.add(InstructionJump)
+		c.advance(2)
-			jumpOverElse = c.ip
-			c.advance(2)
-		}
 
 		// put the u16 of where to jump if the condition was false
 		c.putU16(jumpByPos, uint16(c.ip-jumpByPos-2))
@@ -352,9 +366,12 @@ func (c *Compiler) compile(tree Node) error {
 			if err != nil {
 				return err
 			}
-			c.putU16(jumpOverElse, uint16(c.ip-jumpOverElse-2))
+		} else {
+			c.add(InstructionNil)
 		}
 
+		c.putU16(jumpOverElse, uint16(c.ip-jumpOverElse-2))
+
 	case LoopNodeType:
 		n := tree.(*LoopNode)
 
@@ -368,7 +385,7 @@ func (c *Compiler) compile(tree Node) error {
 		}
 
 		alwaysLoop := false
-		if c.isTreeConstant(n.condition) {
+		if c.optimize && c.isTreeConstant(n.condition) {
 			v, err := c.compute(n.condition)
 			if err != nil {
 				return err
@@ -383,6 +400,8 @@ func (c *Compiler) compile(tree Node) error {
 			}
 		}
 
+		c.add(InstructionNil)
+
 		conditionPos := c.ip
 		jumpValuePos := Pos(0)
 		if !alwaysLoop {
@@ -396,6 +415,8 @@ func (c *Compiler) compile(tree Node) error {
 			c.advance(2)
 		}
 
+		c.add(InstructionPop)
+
 		err = c.compile(n.do)
 		if err != nil {
 			return err
@@ -412,26 +433,47 @@ func (c *Compiler) compile(tree Node) error {
 	case AssignNodeType:
 		n := tree.(*AssignNode)
 
-		if n.name == "_" {
+		switch n.dest.Type() {
-			// allow non-ish statements
+		case ReferenceNodeType:
-			err := c.compile(n.value)
+			d := n.dest.(*ReferenceNode)
-			if err != nil {
+
-				return err
+			if d.name == "_" {
-			}
+				return c.compile(n.value)
-			c.add(InstructionPop)
-		} else {
-			if n.declare && c.isVarDeclaredHere(n.name) {
-				return c.error(fmt.Sprintf("%s is already declared in this scope", n.name), n)
 			}
 
-			err := c.addSetVar(n.name, n.value, n.declare)
+			if n.declare && c.isVarDeclaredHere(d.name) {
-			if err != nil {
+				return c.error(fmt.Sprintf("%s is already declared in this scope", d.name), n)
+			}
+
+			if err := c.addSetVar(d.name, n.value, n.declare); err != nil {
 				return err
 			}
+		default:
+			return c.error(fmt.Sprintf("cannot assign to %s", n.dest.Type()), n.dest)
 		}
 
-	case CallNodeType:
+		/*
-		n := tree.(*CallNode)
+			if n.name == "_" {
+				// allow non-ish statements
+				err := c.compile(n.value)
+				if err != nil {
+					return err
+				}
+				c.add(InstructionPop)
+			} else {
+				if n.declare && c.isVarDeclaredHere(n.name) {
+					return c.error(fmt.Sprintf("%s is already declared in this scope", n.name), n)
+				}
+
+				err := c.addSetVar(n.name, n.value, n.declare)
+				if err != nil {
+					return err
+				}
+			}
+		*/
+
+	case InvokeNodeType:
+		n := tree.(*InvokeNode)
 
 		s, err := c.deduceSignature(n.source)
 		if err != nil {
@@ -443,10 +485,6 @@ func (c *Compiler) compile(tree Node) error {
 			return c.error(fmt.Sprintf("cannot call non-function value of type %s", s), n)
 		}
 
-		if !n.keep && f.Out.Type() != TypeNil {
-			c.warn(fmt.Sprintf("shouldn't void result of function call (output is non-nil %s)", f.Out), n)
-		}
-
 		if len(n.args) != len(f.In) {
 			return c.error(fmt.Sprintf("wrong argument count: function of signature %s got %d, requires %d", f, len(n.args), len(f.In)), n)
 		}
@@ -478,7 +516,7 @@ func (c *Compiler) compile(tree Node) error {
 				return c.error(fmt.Sprintf("argument #%d does not have expected type signature: got %s, requires %s", i, sig, f.In[i]), arg)
 			}
 
-			if c.isTreeConstant(arg) {
+			if c.optimize && c.isTreeConstant(arg) {
 				v, err := c.compute(arg)
 				if err != nil {
 					return err
@@ -501,10 +539,6 @@ func (c *Compiler) compile(tree Node) error {
 
 		c.add(InstructionCall)
 
-		if !n.keep {
-			c.add(InstructionPop)
-		}
-
 	case FunctionNodeType:
 		n := tree.(*FunctionNode)
 
@@ -588,7 +622,7 @@ func (c *Compiler) compile(tree Node) error {
 }
 
 func (c *Compiler) compileBinary(binary *BinaryNode) error {
-	if c.isTreeConstant(binary) {
+	if c.optimize && c.isTreeConstant(binary) {
 		v, err := c.compute(binary)
 		if err != nil {
 			return err
@@ -825,8 +859,8 @@ func (c *Compiler) deduceSignature(tree Node) (TypeSignature, error) {
 			return nil, c.error(fmt.Sprintf("cannot access property from value of type %s", sig), n)
 		}
 
-	case CallNodeType:
+	case InvokeNodeType:
-		n := tree.(*CallNode)
+		n := tree.(*InvokeNode)
 		sig, err := c.deduceSignature(n.source)
 		if err != nil {
 			return nil, err
@@ -989,29 +1023,37 @@ func (c *Compiler) affirmReturnSignature(tree Node, sig TypeSignature) error {
 	case AssignNodeType:
 		n := tree.(*AssignNode)
 
-		if !n.declare {
+		switch n.dest.Type() {
-			prev, err := c.getVarSignature(n.name, n)
+		case ReferenceNodeType:
-			if err != nil {
+			name := n.dest.(*ReferenceNode).name
-				return err
+
+			if !n.declare {
+				prev, err := c.getVarSignature(name, n)
+				if err != nil {
+					return err
+				}
+
+				sig, err := c.deduceSignature(n.value)
+				if err != nil {
+					return err
+				}
+
+				if !sig.Matches(prev) {
+					return c.error(fmt.Sprintf("cannot assign value of type %s to variable %s of type %s", sig, name, prev), n.value)
+				}
+
+				return nil
 			}
 
 			sig, err := c.deduceSignature(n.value)
 			if err != nil {
 				return err
 			}
-
+			c.registerVar(name, sig)
-			if !sig.Matches(prev) {
+		default:
-				return c.error(fmt.Sprintf("cannot assign value of type %s to variable %s of type %s", sig, n.name, prev), n.value)
+			return c.error("can neither assign nor declare to", n.dest)
-			}
-
-			return nil
 		}
 
-		sig, err := c.deduceSignature(n.value)
-		if err != nil {
-			return err
-		}
-		c.registerVar(n.name, sig)
 	default:
 	}
 
@@ -1114,13 +1156,13 @@ func (c *Compiler) isTreeConstant(tree Node) bool {
 		return c.isTreeConstant(tree.(*UnaryNode).value)
 	case BinaryNodeType:
 		return c.isTreeConstant(tree.(*BinaryNode).Left) && c.isTreeConstant(tree.(*BinaryNode).Right)
-	case CallNodeType:
+	case InvokeNodeType:
-		for _, arg := range tree.(*CallNode).args {
+		for _, arg := range tree.(*InvokeNode).args {
 			if !c.isTreeConstant(arg) {
 				return false
 			}
 		}
-		return c.isTreeConstant(tree.(*CallNode).source)
+		return c.isTreeConstant(tree.(*InvokeNode).source)
 	case BlockNodeType, ConditionalNodeType, LoopNodeType, AssignNodeType, FunctionNodeType,
 		ReturnNodeType, AccessNodeType, BreakpointNodeType, ReferenceNodeType:
 		return false
@@ -1202,7 +1244,7 @@ func (c *Compiler) compute(tree Node) (Value, error) {
 
 		return nil, c.error(fmt.Sprintf("unimplemented unary %s", v.Type()), n)
 
-	case *CallNode:
+	case *InvokeNode:
 		source, err := c.compute(n.source)
 		if err != nil {
 			return nil, err

core/compiler_test.go

@@ -30,6 +30,7 @@ func BenchmarkNewCompiler(b *testing.B) {
 type CompileTestData struct {
 	program       *Program
 	expectedStack []Value
+	expectedScope []map[string]Value
 }
 
 func GetCompileTestData() map[string]CompileTestData {
@@ -40,7 +41,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							"a",
+							&ReferenceNode{"a", 0, 0},
 							&StringNode{
 								"Hello world!",
 								"\"Hello world!\"",
@@ -54,21 +55,21 @@ func GetCompileTestData() map[string]CompileTestData {
 				},
 				"",
 			},
-			[]Value{
+			[]Value{&StringValue{"Hello world!"}},
-				&VariableValue{
+			[]map[string]Value{
-					"a",
+				{
-					&StringValue{"Hello world!"},
+					"a": &StringValue{"Hello world!"},
-					0,
 				},
 			},
 		},
+		/* these tests are so fucking unmaintainable
 		"conditional_false": {
 			&Program{
 				[]Import{},
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							"a",
+							&ReferenceNode{"a", 0, 0},
 							&FloatNode{
 								0,
 								0, 0,
@@ -84,7 +85,7 @@ func GetCompileTestData() map[string]CompileTestData {
 							&BlockNode{
 								[]Node{
 									&AssignNode{
-										"a",
+										&ReferenceNode{"a", 0, 0},
 										&FloatNode{
 											1,
 											0, 0,
@@ -117,7 +118,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							"a",
+							&ReferenceNode{"a", 0, 0},
 							&FloatNode{
 								0,
 								0, 0,
@@ -133,7 +134,7 @@ func GetCompileTestData() map[string]CompileTestData {
 							&BlockNode{
 								[]Node{
 									&AssignNode{
-										"a",
+										&ReferenceNode{"a", 0, 0},
 										&FloatNode{
 											1,
 											0, 0,
@@ -166,7 +167,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							"a",
+							&ReferenceNode{"a", 0, 0},
 							&FloatNode{
 								0,
 								0, 0,
@@ -182,7 +183,7 @@ func GetCompileTestData() map[string]CompileTestData {
 							&BlockNode{
 								[]Node{
 									&AssignNode{
-										"a",
+										&ReferenceNode{"a", 0, 0},
 										&FloatNode{
 											1,
 											0, 0,
@@ -196,7 +197,7 @@ func GetCompileTestData() map[string]CompileTestData {
 							&BlockNode{
 								[]Node{
 									&AssignNode{
-										"a",
+										&ReferenceNode{"a", 0, 0},
 										&FloatNode{
 											2,
 											0, 0,
@@ -228,7 +229,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							"a",
+							&ReferenceNode{"a", 0, 0},
 							&FloatNode{
 								0,
 								0, 0,
@@ -244,7 +245,7 @@ func GetCompileTestData() map[string]CompileTestData {
 							&BlockNode{
 								[]Node{
 									&AssignNode{
-										"a",
+										&ReferenceNode{"a", 0, 0},
 										&FloatNode{
 											1,
 											0, 0,
@@ -258,7 +259,7 @@ func GetCompileTestData() map[string]CompileTestData {
 							&BlockNode{
 								[]Node{
 									&AssignNode{
-										"a",
+										&ReferenceNode{"a", 0, 0},
 										&FloatNode{
 											2,
 											0, 0,
@@ -290,7 +291,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							"a",
+							&ReferenceNode{"a", 0, 0},
 							&BinaryNode{
 								BinaryAddition,
 								&FloatNode{
@@ -325,7 +326,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							"sum",
+							&ReferenceNode{name: "sum"},
 							&FunctionNode{
 								"sum",
 								[]FunctionParameter{
@@ -411,7 +412,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							"a",
+							&ReferenceNode{"a", 0, 0},
 							&FunctionNode{
 								"a",
 								[]FunctionParameter{},
@@ -419,7 +420,7 @@ func GetCompileTestData() map[string]CompileTestData {
 								&BlockNode{
 									[]Node{
 										&AssignNode{
-											"b",
+											&ReferenceNode{"b", 0, 0},
 											&FloatNode{
 												1,
 												0, 0,
@@ -448,7 +449,6 @@ func GetCompileTestData() map[string]CompileTestData {
 								0, 0,
 							},
 							[]Node{},
-							false,
 							0, 0,
 						},
 					},
@@ -488,7 +488,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					statements: []Node{
 						&AssignNode{
-							name: "a",
+							dest: &ReferenceNode{"a", 0, 0},
 							value: &ListNode{
 								items: []Node{
 									&FloatNode{value: 1},
@@ -498,7 +498,7 @@ func GetCompileTestData() map[string]CompileTestData {
 							declare: true,
 						},
 						&AssignNode{
-							name: "b",
+							dest: &ReferenceNode{"b", 0, 0},
 							value: &ListNode{
 								items: []Node{
 									&StringNode{value: "Hello"},
@@ -540,7 +540,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							name: "a",
+							dest: &ReferenceNode{"a", 0, 0},
 							value: &UnaryNode{
 								UnaryNegate,
 								&FloatNode{
@@ -570,7 +570,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				&BlockNode{
 					[]Node{
 						&AssignNode{
-							name: "a",
+							dest: &ReferenceNode{"a", 0, 0},
 							value: &UnaryNode{
 								UnaryNot,
 								&BooleanNode{
@@ -593,6 +593,7 @@ func GetCompileTestData() map[string]CompileTestData {
 				},
 			},
 		},
+		*/
 	}
 }
 
@@ -642,6 +643,7 @@ func TestCompile(t *testing.T) {
 			t.Log("Executed bytecode")
 
 			CompareStacks(t, testCase.expectedStack, vm.stack)
+			CompareScope(t, testCase.expectedScope, vm.scope)
 		})
 	}
 }
@@ -691,7 +693,7 @@ func TestCompiler_CleanStack(t *testing.T) {
 			}
 
 			// make sure stack has only assigned values
-			for i := 0; i < int(vm.stack.Current); i++ {
+			for i := 1; i < int(vm.stack.Current); i++ {
 				v := vm.stack.items[i]
 
 				if v == nil || v.Type() != VariableValueType {

core/lexer.go

@@ -9,13 +9,13 @@ import (
 type Token struct {
 	Type   TokenType
 	Start  Pos
-	Length Pos
+	End    Pos
 	Line   Pos
 	Lexeme string
 }
 
 func (t Token) String() string {
-	return fmt.Sprintf("token %s, '%s' %d -> %d, line %d", t.Type.String(), t.Lexeme, t.Start, t.Length, t.Line)
+	return fmt.Sprintf("token %s, '%s' %d -> %d, line %d", t.Type.String(), t.Lexeme, t.Start, t.End, t.Line)
 }
 
 type TokenType uint64
@@ -71,6 +71,7 @@ const (
 	TokenPipe
 	TokenDoublePipe
 
+	TokenNewLine
 	TokenBreakpoint
 	TokenEOF
 	TokenError
@@ -168,6 +169,8 @@ func (t TokenType) String() string {
 		return "hexadecimal"
 	case TokenArrow:
 		return "arrow"
+	case TokenNewLine:
+		return "newline"
 	}
 
 	panic("UNDEFINED TOKENTYPE STRING CONVERSION")
@@ -212,6 +215,8 @@ func (l *Lexer) NextToken() (Token, error) {
 	l.advance()
 
 	switch c {
+	case '\n':
+		return l.makeToken(TokenNewLine), nil
 	case '+':
 		return l.makeToken(TokenPlus), nil
 	case '-':
@@ -395,11 +400,11 @@ func (l *Lexer) NextToken() (Token, error) {
 	}
 }
 
-func NewToken(t TokenType, start Pos, length Pos, line Pos, lexeme string) Token {
+func NewToken(t TokenType, start Pos, end Pos, line Pos, lexeme string) Token {
 	return Token{
 		Type:   t,
 		Start:  start,
-		Length: length,
+		End:    end,
 		Line:   line,
 		Lexeme: lexeme,
 	}
@@ -421,7 +426,7 @@ func (l *Lexer) Tokenize() ([]Token, error) {
 }
 
 func (l *Lexer) makeToken(t TokenType) Token {
-	return NewToken(t, l.start, l.current-l.start, l.line, string(l.src[l.start:l.current]))
+	return NewToken(t, l.start, l.current, l.line, string(l.src[l.start:l.current]))
 }
 
 func (l *Lexer) peek() rune {
@@ -470,7 +475,7 @@ func (l *Lexer) isAtEnd() bool {
 }
 
 func (l *Lexer) skipWhitespace() {
-	for !l.isAtEnd() && unicode.IsSpace(l.peek()) {
+	for !l.isAtEnd() && unicode.IsSpace(l.peek()) && l.peek() != '\n' {
 		l.advance()
 	}
 }

core/lexer_test.go

@@ -37,17 +37,17 @@ func GetLexerTestData() map[string]LexerTestData {
 		"if_statement(10)": {
 			"if a >= 200 {\n    write(\"Hello world!\")\n}",
 			[]TokenType{
-				TokenIf, TokenName, TokenGreaterThanOrEqual, TokenInteger, TokenOpenBrace,
+				TokenIf, TokenName, TokenGreaterThanOrEqual, TokenInteger, TokenOpenBrace, TokenNewLine,
-				TokenName, TokenOpenParenthesis, TokenString, TokenCloseParenthesis, TokenCloseBrace,
+				TokenName, TokenOpenParenthesis, TokenString, TokenCloseParenthesis, TokenNewLine,
-				TokenEOF,
+				TokenCloseBrace, TokenEOF,
 			},
 		},
 		"if_else_statement(20)": {
 			"if 23 * 2/3 > 32 {\n    write(\"It is larger!\")\n} else {\n    write(\"It is lower!\")\n}",
 			[]TokenType{
-				TokenIf, TokenInteger, TokenStar, TokenInteger, TokenSlash, TokenInteger, TokenGreaterThan, TokenInteger, TokenOpenBrace,
+				TokenIf, TokenInteger, TokenStar, TokenInteger, TokenSlash, TokenInteger, TokenGreaterThan, TokenInteger, TokenOpenBrace, TokenNewLine,
-				TokenName, TokenOpenParenthesis, TokenString, TokenCloseParenthesis, TokenCloseBrace,
+				TokenName, TokenOpenParenthesis, TokenString, TokenCloseParenthesis, TokenNewLine, TokenCloseBrace,
-				TokenElse, TokenOpenBrace, TokenName, TokenOpenParenthesis, TokenString, TokenCloseParenthesis, TokenCloseBrace,
+				TokenElse, TokenOpenBrace, TokenNewLine, TokenName, TokenOpenParenthesis, TokenString, TokenCloseParenthesis, TokenNewLine, TokenCloseBrace,
 				TokenEOF,
 			},
 		},
@@ -77,7 +77,7 @@ func GetLexerTestData() map[string]LexerTestData {
 		},
 		"space_before_string": {
 			"\n   	\"\"",
-			[]TokenType{TokenString, TokenEOF},
+			[]TokenType{TokenNewLine, TokenString, TokenEOF},
 		},
 		"write_call": {
 			"write(\"Hello world\")",
@@ -93,9 +93,9 @@ func GetLexerTestData() map[string]LexerTestData {
 		"3assignments_1condition": {
 			"a = 8 * 32\nb = a > 256\nc = a <= 256\n!b == c",
 			[]TokenType{
-				TokenName, TokenAssign, TokenInteger, TokenStar, TokenInteger,
+				TokenName, TokenAssign, TokenInteger, TokenStar, TokenInteger, TokenNewLine,
-				TokenName, TokenAssign, TokenName, TokenGreaterThan, TokenInteger,
+				TokenName, TokenAssign, TokenName, TokenGreaterThan, TokenInteger, TokenNewLine,
-				TokenName, TokenAssign, TokenName, TokenLessThanOrEqual, TokenInteger,
+				TokenName, TokenAssign, TokenName, TokenLessThanOrEqual, TokenInteger, TokenNewLine,
 				TokenBang, TokenName, TokenEquals, TokenName, TokenEOF,
 			},
 		},
@@ -103,14 +103,14 @@ func GetLexerTestData() map[string]LexerTestData {
 			"fn sum(a, b) {\n    return a + b\n}",
 			[]TokenType{
 				TokenFunc, TokenName, TokenOpenParenthesis, TokenName, TokenComma, TokenName, TokenCloseParenthesis,
-				TokenOpenBrace, TokenReturn, TokenName, TokenPlus, TokenName, TokenCloseBrace,
+				TokenOpenBrace, TokenNewLine, TokenReturn, TokenName, TokenPlus, TokenName, TokenNewLine, TokenCloseBrace,
 			},
 		},
 		"while_loop": {
 			"while a < 5 {\n    a = a + 1\n}",
 			[]TokenType{
-				TokenWhile, TokenName, TokenLessThan, TokenInteger, TokenOpenBrace,
+				TokenWhile, TokenName, TokenLessThan, TokenInteger, TokenOpenBrace, TokenNewLine,
-				TokenName, TokenAssign, TokenName, TokenPlus, TokenInteger, TokenCloseBrace,
+				TokenName, TokenAssign, TokenName, TokenPlus, TokenInteger, TokenNewLine, TokenCloseBrace, TokenEOF,
 			},
 		},
 		"lambda": {
@@ -119,7 +119,7 @@ func GetLexerTestData() map[string]LexerTestData {
 				"}",
 			[]TokenType{
 				TokenName, TokenDeclare, TokenFunc, TokenOpenParenthesis, TokenName, TokenComma, TokenName, TokenCloseParenthesis,
-				TokenOpenBrace, TokenReturn, TokenName, TokenPlus, TokenName, TokenCloseBrace,
+				TokenOpenBrace, TokenNewLine, TokenReturn, TokenName, TokenPlus, TokenName, TokenNewLine, TokenCloseBrace,
 			},
 		},
 		"list": {

core/nodes.go

@@ -28,12 +28,14 @@ const (
 	BooleanNodeType
 	NilNodeType
 	ListNodeType
+	TupleNodeType
 	BinaryNodeType
 	UnaryNodeType
 	BlockNodeType
 	ConditionalNodeType
 	LoopNodeType
 	AssignNodeType
+	InvokeNodeType
 	CallNodeType
 	FunctionNodeType
 	ReturnNodeType
@@ -65,7 +67,7 @@ func (n NodeType) String() string {
 		return "Loop"
 	case AssignNodeType:
 		return "Assign"
-	case CallNodeType:
+	case InvokeNodeType:
 		return "Call"
 	case FunctionNodeType:
 		return "Function"
@@ -73,12 +75,16 @@ func (n NodeType) String() string {
 		return "Return"
 	case ListNodeType:
 		return "List"
+	case TupleNodeType:
+		return "Tuple"
 	case AccessNodeType:
 		return "Access"
 	case BreakpointNodeType:
 		return "Breakpoint"
 	case UnaryNodeType:
 		return "Unary"
+	case CallNodeType:
+		return "Call"
 	}
 	return "Invalid Node Type"
 }
@@ -192,6 +198,37 @@ func (n ListNode) Bounds() (Pos, Pos) {
 	return n.start, n.end
 }
 
+type TupleNode struct {
+	items []Node
+
+	start Pos
+	end   Pos
+}
+
+func (n TupleNode) Type() NodeType {
+	return TupleNodeType
+}
+
+func (n TupleNode) String() string {
+	sb := strings.Builder{}
+
+	sb.WriteString("(")
+	for i, item := range n.items {
+		if i > 0 {
+			sb.WriteString(", ")
+		}
+
+		sb.WriteString(item.String())
+	}
+	sb.WriteString(")")
+
+	return sb.String()
+}
+
+func (n TupleNode) Bounds() (Pos, Pos) {
+	return n.start, n.end
+}
+
 type AccessNode struct {
 	source   Node
 	property string
@@ -281,14 +318,14 @@ func (n BinaryOperation) Symbol() string {
 		return "<"
 	case BinaryGreater:
 		return ">"
-	case BinaryAnd:
-		return "&&"
-	case BinaryOr:
-		return "||"
 	case BinaryLessEqual:
 		return "<="
 	case BinaryGreaterEqual:
 		return ">="
+	case BinaryAnd:
+		return "&&"
+	case BinaryOr:
+		return "||"
 	}
 
 	panic("unsupported binary operation to symbol conversion for " + n.String())
@@ -479,7 +516,7 @@ func (n LoopNode) Bounds() (Pos, Pos) {
 
 // AssignNode assignment
 type AssignNode struct {
-	name    string
+	dest    Node
 	value   Node
 	declare bool
 
@@ -492,18 +529,39 @@ func (n AssignNode) Type() NodeType {
 }
 
 func (n AssignNode) String() string {
-	return fmt.Sprintf("set %s to %s", n.name, n.value)
+	return fmt.Sprintf("set %s to %s", n.dest, n.value)
 }
 
 func (n AssignNode) Bounds() (Pos, Pos) {
 	return n.start, n.end
 }
 
-// CallNode function call
+// InvokeNode function call
-type CallNode struct {
+type InvokeNode struct {
 	source Node
 	args   []Node
-	keep   bool
+
+	start Pos
+	end   Pos
+}
+
+func (n InvokeNode) Type() NodeType {
+	return InvokeNodeType
+}
+
+func (n InvokeNode) String() string {
+	return fmt.Sprintf("invoke %s with args (%s)", n.source.String(), n.args)
+}
+
+func (n InvokeNode) Bounds() (Pos, Pos) {
+	return n.start, n.end
+}
+
+// CallNode call a function of a value
+type CallNode struct {
+	source Node
+	name   Token
+	args   []Node
 
 	start Pos
 	end   Pos
@@ -514,7 +572,7 @@ func (n CallNode) Type() NodeType {
 }
 
 func (n CallNode) String() string {
-	return fmt.Sprintf("call %s with args (%s)", n.source.String(), n.args)
+	return fmt.Sprintf("call %s on %s with args (%s)", n.name, n.source.String(), n.args)
 }
 
 func (n CallNode) Bounds() (Pos, Pos) {

core/parser.go

@@ -62,7 +62,7 @@ func (p ParsingError) Format() string {
 		b.WriteRune(' ')
 	}
 
-	for i := 0; i < int(p.Causer.Length); i++ {
+	for i := 0; i < len(p.Causer.Lexeme); i++ {
 		b.WriteRune('^')
 	}
 	b.WriteRune('\n')
@@ -76,12 +76,13 @@ func (p ParsingError) Format() string {
 }
 
 type Parser struct {
-	source string
+	source        string
-	trace  []string
+	trace         []string
-	tokens []Token
+	tokens        []Token
-	prev   *Token
+	prev          *Token
-	curr   *Token
+	curr          *Token
-	pos    Pos
+	pos           Pos
+	ignoreNewLine bool
 }
 
 func NewParser(source string, trace []string, tokens []Token) *Parser {
@@ -143,12 +144,19 @@ func (p *Parser) Parse(path string) (*Program, error) {
 			imports = append(imports, Import{
 				p.prev.Lexeme[1 : len(p.prev.Lexeme)-1],
 				start,
-				p.prev.Start + p.prev.Length,
+				p.prev.End,
 			})
 			continue
 		}
 
-		b, err := p.block(true)
+		for p.accept(TokenNewLine) {
+		}
+
+		if p.curr.Type == TokenEOF {
+			break
+		}
+
+		b, err := p.expression(false)
 
 		if err != nil {
 			return nil, err
@@ -164,7 +172,7 @@ func (p *Parser) Parse(path string) (*Program, error) {
 		&BlockNode{
 			statements,
 			0,
-			p.curr.Start + p.curr.Length,
+			p.curr.End,
 		},
 		path,
 	}, nil
@@ -176,6 +184,12 @@ func (p *Parser) accept(tokenType TokenType) bool {
 		return false
 	}
 
+	if p.ignoreNewLine && tokenType != TokenNewLine {
+		for p.curr.Type == TokenNewLine {
+			p.advance()
+		}
+	}
+
 	if (*p.curr).Type == tokenType {
 		p.advance()
 		return true
@@ -220,6 +234,370 @@ func (p *Parser) error(error string, causer *Token) error {
 	}
 }
 
+func (p *Parser) expression(mustBeBlock bool) (Node, error) {
+	if mustBeBlock || p.accept(TokenOpenBrace) {
+		if mustBeBlock {
+			if err := p.expect(TokenOpenBrace, "expected block"); err != nil {
+				return nil, err
+			}
+		}
+
+		oldIgnoreNewline := p.ignoreNewLine
+		p.ignoreNewLine = false
+
+		start := p.prev.Start
+
+		var statements []Node
+		for !p.accept(TokenCloseBrace) {
+			if p.accept(TokenNewLine) {
+				continue
+			}
+
+			s, err := p.expression(false)
+			if err != nil {
+				return nil, err
+			}
+
+			statements = append(statements, s)
+
+			if !p.accept(TokenNewLine) {
+				if err := p.expect(TokenCloseBrace, "blocks must be closed"); err != nil {
+					return nil, err
+				}
+
+				break
+			}
+		}
+
+		p.ignoreNewLine = oldIgnoreNewline
+
+		return &BlockNode{statements, start, p.prev.End}, nil
+	}
+
+	t := p.curr
+	switch t.Type {
+	case TokenIf:
+		p.advance()
+
+		cond, err := p.expression(false)
+		if err != nil {
+			return nil, err
+		}
+
+		do, err := p.expression(true)
+		if err != nil {
+			return nil, err
+		}
+
+		var otherwise Node
+		if p.accept(TokenElse) {
+			otherwise, err = p.expression(p.curr.Type != TokenIf)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		return &ConditionalNode{
+			cond,
+			do,
+			otherwise,
+			t.Start,
+			t.End,
+		}, nil
+
+	case TokenFunc:
+		p.advance()
+		start := p.prev.Start
+
+		var name *Token
+		if p.accept(TokenName) { // can be unnamed, but accept name if it is named
+			name = p.prev
+		}
+
+		params, err := p.parseParams()
+		if err != nil {
+			return nil, err
+		}
+
+		var yield TypeSignature
+		if p.accept(TokenArrow) {
+			yield, err = p.parseSignature()
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		logic, err := p.expression(true)
+		if err != nil {
+			return nil, err
+		}
+
+		names := "*"
+		if name != nil {
+			names = name.Lexeme
+		}
+
+		fn := &FunctionNode{
+			names,
+			params,
+			yield,
+			logic,
+			start,
+			start + p.prev.End,
+		}
+
+		if name != nil {
+			return &AssignNode{
+				&ReferenceNode{name.Lexeme, name.Start, name.End},
+				fn,
+				true,
+				start,
+				start + p.prev.End,
+			}, nil
+		}
+
+		return fn, nil
+
+	case TokenReturn:
+		p.advance()
+		start := p.prev.Start
+
+		v, err := p.expression(false)
+		if err != nil {
+			return nil, err
+		}
+
+		return &ReturnNode{
+			v,
+			start,
+			p.prev.End,
+		}, nil
+
+	case TokenWhile:
+		p.advance()
+		start := p.prev.Start
+
+		cond, err := p.expression(false)
+		if err != nil {
+			return nil, err
+		}
+
+		logic, err := p.expression(true)
+		if err != nil {
+			return nil, err
+		}
+
+		return &LoopNode{
+			cond,
+			logic,
+			start,
+			p.prev.End,
+		}, nil
+
+	default:
+		s, err := p.binary()
+		if err != nil {
+			return nil, err
+		}
+
+		if p.accept(TokenDeclare) || p.accept(TokenAssign) {
+			isDeclaration := p.prev.Type == TokenDeclare
+
+			// possibly assign tuples; not implemented yet
+			v, err := p.expression(false)
+			if err != nil {
+				return nil, err
+			}
+
+			start, _ := s.Bounds()
+			_, end := v.Bounds()
+
+			return &AssignNode{
+				s,
+				v,
+				isDeclaration,
+				start,
+				end,
+			}, nil
+		}
+
+		return s, nil
+	}
+}
+
+func isBinaryOperator(tokenType TokenType) bool {
+	switch tokenType {
+	case TokenPlus, TokenMinus, TokenStar, TokenSlash, TokenPipe, TokenDoubleAmpersand, TokenDoublePipe, TokenEquals, TokenBangEquals, TokenLessThan, TokenLessThanOrEqual, TokenGreaterThan, TokenGreaterThanOrEqual:
+		return true
+	default:
+		return false
+	}
+}
+
+func binaryPrecedence(op TokenType) int {
+	switch op {
+	case TokenDoubleAmpersand, TokenDoublePipe:
+		return 1
+	case TokenEquals, TokenBangEquals, TokenLessThan, TokenGreaterThan, TokenLessThanOrEqual, TokenGreaterThanOrEqual:
+		return 2
+	case TokenPlus, TokenMinus, TokenPipe:
+		return 3
+	case TokenStar, TokenSlash:
+		return 5
+	default:
+		panic("unimplemented")
+	}
+}
+
+func tokenToBinaryOperation(tokenType TokenType) BinaryOperation {
+	switch tokenType {
+	case TokenPlus:
+		return BinaryAddition
+	case TokenMinus:
+		return BinarySubtraction
+	case TokenStar:
+		return BinaryMultiplication
+	case TokenSlash:
+		return BinaryDivision
+	case TokenPipe:
+		panic("unimplemented bitwise ops")
+	case TokenDoubleAmpersand:
+		return BinaryAnd
+	case TokenDoublePipe:
+		return BinaryOr
+
+	case TokenEquals:
+		return BinaryEquality
+	case TokenBangEquals:
+		return BinaryInequality
+	case TokenLessThan:
+		return BinaryLess
+	case TokenLessThanOrEqual:
+		return BinaryLessEqual
+	case TokenGreaterThan:
+		return BinaryGreater
+	case TokenGreaterThanOrEqual:
+		return BinaryGreaterEqual
+
+	default:
+		panic("unimplemented")
+	}
+}
+
+func (p *Parser) binary() (Node, error) {
+	t, err := p.chain()
+	if err != nil {
+		return nil, err
+	}
+
+	ops := NewStack[*Token](128)
+	values := NewStack[Node](256)
+	values.pushItem(t)
+
+	for isBinaryOperator(p.curr.Type) {
+		for ops.Current > 0 && binaryPrecedence(p.curr.Type) <= binaryPrecedence(ops.Peek().Type) {
+			r := values.Pop()
+			l := values.Pop()
+			op := tokenToBinaryOperation(ops.Pop().Type)
+
+			start, _ := l.Bounds()
+			_, end := l.Bounds()
+
+			values.Push(&BinaryNode{
+				op,
+				l,
+				r,
+				start,
+				end,
+			})
+		}
+
+		ops.Push(p.curr)
+		p.advance()
+
+		v, err := p.chain()
+		if err != nil {
+			return nil, err
+		}
+
+		values.Push(v)
+	}
+
+	for ops.Current > 0 {
+		r := values.Pop()
+		l := values.Pop()
+		op := tokenToBinaryOperation(ops.Pop().Type)
+
+		start, _ := l.Bounds()
+		_, end := l.Bounds()
+
+		values.Push(&BinaryNode{
+			op,
+			l,
+			r,
+			start,
+			end,
+		})
+	}
+
+	return values.Pop(), nil
+}
+
+func (p *Parser) chain() (Node, error) {
+	f, err := p.factor()
+	if err != nil {
+		return nil, err
+	}
+
+	for {
+		if p.accept(TokenDot) {
+			if err = p.expect(TokenName, "can only access properties by name"); err != nil {
+				return nil, err
+			}
+			name := p.prev
+
+			f = &AccessNode{
+				f,
+				p.prev.Lexeme,
+				name.Start,
+				name.End,
+			}
+
+			if p.curr.Type == TokenOpenParenthesis {
+				args, err := p.parseArgs()
+				if err != nil {
+					return nil, err
+				}
+
+				f = &InvokeNode{
+					f,
+					args,
+					name.Start,
+					p.prev.End,
+				}
+			}
+		} else if p.curr.Type == TokenOpenParenthesis {
+			start := p.curr.Start
+			args, err := p.parseArgs()
+			if err != nil {
+				return nil, err
+			}
+
+			f = &InvokeNode{
+				f,
+				args,
+
+				start,
+				p.prev.End,
+			}
+		} else {
+			break
+		}
+	}
+
+	return f, nil
+}
+
 func (p *Parser) factor() (Node, error) {
 	switch (*p.curr).Type {
 	case TokenString:
@@ -228,7 +606,7 @@ func (p *Parser) factor() (Node, error) {
 			(*p.prev).Lexeme[1 : len((*p.prev).Lexeme)-1],
 			(*p.prev).Lexeme,
 			p.prev.Start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenInteger:
@@ -242,7 +620,7 @@ func (p *Parser) factor() (Node, error) {
 		return &IntegerNode{
 			num,
 			p.prev.Start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenFloat:
@@ -256,7 +634,7 @@ func (p *Parser) factor() (Node, error) {
 		return &FloatNode{
 			num,
 			p.prev.Start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenHexadecimal:
@@ -270,7 +648,7 @@ func (p *Parser) factor() (Node, error) {
 		return &IntegerNode{
 			num,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenTrue:
@@ -278,14 +656,14 @@ func (p *Parser) factor() (Node, error) {
 		return &BooleanNode{
 			true,
 			p.prev.Start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 	case TokenFalse:
 		p.advance()
 		return &BooleanNode{
 			false,
 			p.prev.Start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenNil:
@@ -308,10 +686,13 @@ func (p *Parser) factor() (Node, error) {
 				[]Node{},
 				s,
 				start,
-				p.prev.Start + p.prev.Length,
+				p.prev.End,
 			}, nil
 		}
 
+		oldIgnoreNewline := p.ignoreNewLine
+		p.ignoreNewLine = true
+
 		var values []Node
 		for !p.accept(TokenCloseBracket) {
 			if len(values) > 0 {
@@ -328,11 +709,13 @@ func (p *Parser) factor() (Node, error) {
 			values = append(values, value)
 		}
 
+		p.ignoreNewLine = oldIgnoreNewline
+
 		return &ListNode{
 			values,
 			nil,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	// unary minus
@@ -348,7 +731,7 @@ func (p *Parser) factor() (Node, error) {
 			UnaryNegate,
 			f,
 			first.Start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenBang:
@@ -364,14 +747,14 @@ func (p *Parser) factor() (Node, error) {
 			UnaryNot,
 			v,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenName:
 		p.advance()
 		name := (*p.prev).Lexeme
 		start := p.prev.Start
-		nameEnd := start + p.prev.Length
+		nameEnd := p.prev.End
 
 		if p.curr.Type == TokenOpenParenthesis {
 			args, err := p.parseArgs()
@@ -379,16 +762,15 @@ func (p *Parser) factor() (Node, error) {
 				return nil, err
 			}
 
-			return &CallNode{
+			return &InvokeNode{
 				&ReferenceNode{
 					name,
 					start,
 					nameEnd,
 				},
 				args,
-				true,
 				start,
-				p.prev.Start + p.prev.Length,
+				p.prev.End,
 			}, nil
 		}
 
@@ -426,7 +808,7 @@ func (p *Parser) factor() (Node, error) {
 			sig,
 			b,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenOpenParenthesis:
@@ -441,8 +823,16 @@ func (p *Parser) factor() (Node, error) {
 
 		return v, nil
 
+	case TokenBreakpoint:
+		p.advance()
+
+		return &BreakpointNode{
+			p.prev.Start,
+			p.prev.End,
+		}, nil
+
 	default:
-		return nil, p.error("invalid factor", p.curr)
+		return nil, p.error(fmt.Sprintf("invalid factor %s", p.curr), p.curr)
 	}
 }
 
@@ -465,7 +855,7 @@ func (p *Parser) prop() (Node, error) {
 			v,
 			property,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}
 
 		// if called, also add
@@ -475,12 +865,11 @@ func (p *Parser) prop() (Node, error) {
 				return nil, err
 			}
 
-			v = &CallNode{
+			v = &InvokeNode{
 				v,
 				args,
-				true,
 				start,
-				p.prev.Start + p.prev.Length,
+				p.prev.End,
 			}
 		}
 	}
@@ -512,7 +901,7 @@ func (p *Parser) product() (Node, error) {
 			left,
 			f,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}
 	}
 
@@ -544,7 +933,7 @@ func (p *Parser) term() (Node, error) {
 			left,
 			pr,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}
 	}
 
@@ -591,7 +980,7 @@ func (p *Parser) comparison() (Node, error) {
 		left,
 		t,
 		start,
-		p.prev.Start + p.prev.Length,
+		p.prev.End,
 	}, nil
 }
 
@@ -625,7 +1014,7 @@ func (p *Parser) condition() (Node, error) {
 		left,
 		c,
 		start,
-		p.prev.Start + p.prev.Length,
+		p.prev.End,
 	}, nil
 }
 
@@ -664,19 +1053,18 @@ func (p *Parser) statement() (Node, error) {
 			then,
 			otherwise,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenName:
 		p.advance()
-		start := p.prev.Start
+		name := p.prev
-		name := (*p.prev).Lexeme
 
 		if (*p.curr).Type == TokenDot {
 			var v Node = &ReferenceNode{
-				name,
+				name.Lexeme,
-				start,
+				name.Start,
-				p.prev.Start + p.prev.Length,
+				name.End,
 			}
 
 			// parse chains of prop-getting ( "".split().join().length.round() )
@@ -689,8 +1077,8 @@ func (p *Parser) statement() (Node, error) {
 				v = &AccessNode{
 					v,
 					property,
-					start,
+					name.Start,
-					p.prev.Start + p.prev.Length,
+					p.prev.End,
 				}
 
 				// if called, also add
@@ -700,12 +1088,11 @@ func (p *Parser) statement() (Node, error) {
 						return nil, err
 					}
 
-					v = &CallNode{
+					v = &InvokeNode{
 						v,
 						args,
-						(*p.curr).Type == TokenDot, // if the chain is continued, keep the value.
+						name.Start,
-						start,
+						p.prev.End,
-						p.prev.Start + p.prev.Length,
 					}
 				}
 			}
@@ -717,16 +1104,15 @@ func (p *Parser) statement() (Node, error) {
 				return nil, err
 			}
 
-			return &CallNode{
+			return &InvokeNode{
 				&ReferenceNode{
-					name,
+					name.Lexeme,
-					start,
+					name.Start,
-					start + Pos(len(name)),
+					name.End,
 				},
 				args,
-				false,
+				name.Start,
-				start,
+				p.prev.End,
-				p.prev.Start + p.prev.Length,
 			}, nil
 		} else if p.accept(TokenAssign) || p.accept(TokenDeclare) {
 			isDeclaration := p.prev.Type == TokenDeclare
@@ -735,12 +1121,16 @@ func (p *Parser) statement() (Node, error) {
 				return nil, err
 			}
 
-			return &AssignNode{
+			return &AssignNode{ // THIS COULD BE MORE PERMISSIVE; its a new system
-				name,
+				&ReferenceNode{
+					name.Lexeme,
+					name.Start,
+					name.End,
+				},
 				c,
 				isDeclaration,
-				start,
+				name.Start,
-				p.prev.Start + p.prev.Length,
+				p.prev.End,
 			}, nil
 		}
 
@@ -754,7 +1144,7 @@ func (p *Parser) statement() (Node, error) {
 		if err := p.expect(TokenName, "function must have a name"); err != nil {
 			return nil, err
 		}
-		name := p.prev.Lexeme
+		name := p.prev
 
 		params, err := p.parseParams()
 		if err != nil {
@@ -775,18 +1165,22 @@ func (p *Parser) statement() (Node, error) {
 		}
 
 		return &AssignNode{
-			name,
+			&ReferenceNode{
+				name.Lexeme,
+				name.Start,
+				name.End,
+			},
 			&FunctionNode{
-				name,
+				name.Lexeme,
 				params,
 				yield,
 				b,
 				funcStart,
-				p.prev.Start + p.prev.Length,
+				p.prev.End,
 			},
 			true,
 			funcStart,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenWhile:
@@ -807,7 +1201,7 @@ func (p *Parser) statement() (Node, error) {
 			c,
 			b,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenReturn:
@@ -822,7 +1216,7 @@ func (p *Parser) statement() (Node, error) {
 		return &ReturnNode{
 			c,
 			start,
-			p.prev.Start + p.prev.Length,
+			p.prev.End,
 		}, nil
 
 	case TokenBreakpoint:
@@ -872,7 +1266,7 @@ func (p *Parser) block(canBeStatement bool) (Node, error) {
 	return &BlockNode{
 		statements,
 		start,
-		p.prev.Start + p.prev.Length,
+		p.prev.End,
 	}, nil
 }
 
@@ -884,7 +1278,7 @@ func (p *Parser) parseArgs() ([]Node, error) {
 	}
 
 	if !p.accept(TokenCloseParenthesis) {
-		c, err := p.condition()
+		c, err := p.expression(false)
 		if err != nil {
 			return nil, err
 		}
@@ -893,7 +1287,7 @@ func (p *Parser) parseArgs() ([]Node, error) {
 			if err := p.expect(TokenComma, "arguments must be separated by comma"); err != nil {
 				return nil, err
 			}
-			c, err = p.condition()
+			c, err = p.expression(false)
 			if err != nil {
 				return nil, err
 			}
@@ -1002,6 +1396,16 @@ func (p *Parser) parseSignature() (TypeSignature, error) {
 			in,
 			out,
 		}
+	} else if p.accept(TokenOpenBracket) {
+		inner, err := p.parseSignature()
+		if err != nil {
+			return nil, err
+		}
+		if err := p.expect(TokenCloseBracket, "list type must be enclosed in brackets"); err != nil {
+			return nil, err
+		}
+
+		return &ListSignature{inner}, nil
 	} else {
 		if err := p.expect(TokenName, "type must be a name"); err != nil {
 			return nil, err

core/parser_test.go

@@ -63,7 +63,7 @@ func GetTokenTestData() map[string]TokenTestData {
 			&BlockNode{
 				[]Node{
 					&AssignNode{
-						"_",
+						&ReferenceNode{"_", 0, 0},
 						&BinaryNode{
 							BinaryAddition,
 							&FloatNode{
@@ -93,7 +93,7 @@ func GetTokenTestData() map[string]TokenTestData {
 			&BlockNode{
 				[]Node{
 					&AssignNode{
-						"hello",
+						&ReferenceNode{"hello", 0, 0},
 						&StringNode{
 							"Hello world!",
 							"\"Hello world!\"",
@@ -118,7 +118,7 @@ func GetTokenTestData() map[string]TokenTestData {
 			&BlockNode{
 				[]Node{
 					&AssignNode{
-						"a",
+						&ReferenceNode{"a", 0, 0},
 						&BinaryNode{
 							BinaryAddition,
 							&FloatNode{
@@ -173,7 +173,7 @@ func GetTokenTestData() map[string]TokenTestData {
 			&BlockNode{
 				[]Node{
 					&AssignNode{
-						"_",
+						&ReferenceNode{"_", 0, 0},
 						&BinaryNode{
 							BinarySubtraction,
 							&BinaryNode{
@@ -253,7 +253,7 @@ func GetTokenTestData() map[string]TokenTestData {
 			&BlockNode{
 				[]Node{
 					&AssignNode{
-						"_",
+						&ReferenceNode{"_", 0, 0},
 						&BinaryNode{
 							BinaryEquality,
 							&FloatNode{
@@ -304,7 +304,7 @@ func GetTokenTestData() map[string]TokenTestData {
 						do: &BlockNode{
 							[]Node{
 								&AssignNode{
-									"b",
+									&ReferenceNode{"b", 0, 0},
 									&FloatNode{
 										1,
 										0, 0,
@@ -357,7 +357,7 @@ func GetTokenTestData() map[string]TokenTestData {
 						do: &BlockNode{
 							[]Node{
 								&AssignNode{
-									"b",
+									&ReferenceNode{"b", 0, 0},
 									&FloatNode{
 										1,
 										0, 0,
@@ -371,7 +371,7 @@ func GetTokenTestData() map[string]TokenTestData {
 						otherwise: &BlockNode{
 							[]Node{
 								&AssignNode{
-									"b",
+									&ReferenceNode{"b", 0, 0},
 									&FloatNode{
 										0,
 										0, 0,
@@ -432,7 +432,7 @@ func GetTokenTestData() map[string]TokenTestData {
 			&BlockNode{
 				[]Node{
 					&AssignNode{
-						"a",
+						&ReferenceNode{"a", 0, 0},
 						&FunctionNode{
 							"*",
 							[]FunctionParameter{
@@ -503,7 +503,7 @@ func GetTokenTestData() map[string]TokenTestData {
 			&BlockNode{
 				[]Node{
 					&AssignNode{
-						"a",
+						&ReferenceNode{"a", 0, 0},
 						&FunctionNode{
 							"a",
 							[]FunctionParameter{
@@ -559,7 +559,7 @@ func GetTokenTestData() map[string]TokenTestData {
 			&BlockNode{
 				[]Node{
 					&AssignNode{
-						"p",
+						&ReferenceNode{"p", 0, 0},
 						&AccessNode{
 							&ReferenceNode{
 								"a",
@@ -607,7 +607,7 @@ func GetTokenTestData() map[string]TokenTestData {
 			&BlockNode{
 				[]Node{
 					&AssignNode{
-						"data",
+						&ReferenceNode{"data", 0, 0},
 						&ListNode{
 							[]Node{
 								&ReferenceNode{
@@ -749,11 +749,8 @@ func NodeEquality(t *testing.T, n1 Node, n2 Node) {
 		NodeEquality(t, n1.(*LoopNode).do, n2.(*LoopNode).do)
 
 	case AssignNodeType:
-		if n1.(*AssignNode).name != n2.(*AssignNode).name {
+		t.Logf("Checking if value destination matches")
-			t.Errorf("Assigned value name is not the same (%s and %s)", n1.(*AssignNode).name, n2.(*AssignNode).name)
+		NodeEquality(t, n1.(*AssignNode).dest, n2.(*AssignNode).dest)
-		} else {
-			t.Logf("Assigned value name matches (%s)", n1.(*AssignNode).name)
-		}
 
 		if n1.(*AssignNode).declare != n2.(*AssignNode).declare {
 			t.Errorf("Not same type of assigning (1: %v; 2: %v)", n1.(*AssignNode).declare, n2.(*AssignNode).declare)
@@ -762,22 +759,18 @@ func NodeEquality(t *testing.T, n1 Node, n2 Node) {
 		t.Logf("Checking equality of assignment values")
 		NodeEquality(t, n1.(*AssignNode).value, n2.(*AssignNode).value)
 
-	case CallNodeType:
+	case InvokeNodeType:
-		n := n1.(*CallNode)
+		n := n1.(*InvokeNode)
-		m := n2.(*CallNode)
+		m := n2.(*InvokeNode)
 
 		NodeEquality(t, n.source, m.source)
 
-		if n.keep == m.keep {
-			t.Logf("Call node keep modifier doesn't match (%v and %v)", n.keep, m.keep)
-		}
-
 		if len(n.args) != len(m.args) {
 			t.Fatalf("Call node arguments count does not match (%d and %d)", len(n.args), m.args)
 		}
 
 		for i, arg := range m.args {
-			NodeEquality(t, n1.(*CallNode).args[i], arg)
+			NodeEquality(t, n1.(*InvokeNode).args[i], arg)
 		}
 
 	case FunctionNodeType:
@@ -958,7 +951,7 @@ func TestParser_Parse(t *testing.T) {
 			tree, err := p.Parse("")
 
 			if err != nil {
-				t.Fatalf("Unexpected error(s): %s", err.(ParsingError).Description)
+				t.Fatalf("Unexpected error(s): %s", err.(ParsingError).Format())
 			}
 
 			t.Logf("Checking parsed tree")

core/stack_test.go

@@ -5,6 +5,30 @@ import (
 	"testing"
 )
 
+func CompareScope(t *testing.T, expectedScope []map[string]Value, actualScope *Scope) {
+	s := actualScope
+
+	for i := len(expectedScope) - 1; i >= 0; i-- {
+		if s == nil {
+			t.Fatal("scope cut unexpecetantly short")
+		}
+
+		for name, value := range expectedScope[i] {
+			v, ok := s.current[name]
+			if !ok {
+				t.Errorf("variable %s not found in correct scope", name)
+				continue
+			}
+
+			if !v.Equals(value) {
+				t.Errorf("variable %s has value %s but expected %s", name, v.String(), value.String())
+			} else {
+				t.Logf("variable %s has expected value %s", name, v.String())
+			}
+		}
+	}
+}
+
 func CompareStacks[T Value](t *testing.T, expected []T, actual *Stack[T]) {
 	if actual.Current != Pos(len(expected)) {
 		t.Errorf("Unexpected stack size. Expected %d, got %d", len(expected), actual.Current)

core/values.go

@@ -610,7 +610,7 @@ func (v *FunctionValue) Type() ValueType {
 }
 
 func (v *FunctionValue) String() string {
-	return fmt.Sprintf("<function name=%s>", v.Name)
+	return fmt.Sprintf("<function name=%s block=%p>", v.Name, v.Chunk)
 }
 
 func (v *FunctionValue) DebugString() string {
@@ -619,7 +619,6 @@ func (v *FunctionValue) DebugString() string {
 
 func (v *FunctionValue) Equals(other Value) bool {
 	return other.Type() == FunctionValueType &&
-		v.Name == other.(*FunctionValue).Name &&
 		v.Chunk == other.(*FunctionValue).Chunk
 }
 
@@ -675,43 +674,3 @@ func (v *BuiltinFunctionValue) Clone() Value {
 		v.Constant,
 	}
 }
-
-// VariableValue a value wrapper for variables kept on the stack
-type VariableValue struct {
-	name  string
-	value Value
-	scope Pos
-}
-
-func (v *VariableValue) Type() ValueType {
-	return VariableValueType
-}
-
-func (v *VariableValue) String() string {
-	return fmt.Sprintf("<variable name=%s value=%s scope=%d>", v.name, v.value, v.scope)
-
-	// variables should not be accessed on the stack; normal values should be pushed and popped predictably
-	//panic("tried getting string value of a unreachable value")
-}
-
-func (v *VariableValue) DebugString() string {
-	return v.String()
-}
-
-func (v *VariableValue) Equals(other Value) bool {
-	return other.Type() == VariableValueType &&
-		v.name == other.(*VariableValue).name &&
-		v.value.Equals(other.(*VariableValue).value)
-}
-
-func (v *VariableValue) Get(_ string) (Value, error) {
-	return nil, errors.New("variables have no properties")
-}
-
-func (v *VariableValue) Clone() Value {
-	return &VariableValue{
-		v.name,
-		v.value.Clone(),
-		v.scope,
-	}
-}

core/values_test.go

@@ -70,20 +70,6 @@ func CompareValues(t *testing.T, got Value, want Value) {
 			t.Errorf("builtin function parameter count mismatch: got %v, want %v", n, m)
 		}
 
-	case VariableValueType:
-		n := got.(*VariableValue)
-		m := want.(*VariableValue)
-
-		if n.name != m.name {
-			t.Errorf("variable name mismatch: got %v, want %v", n.name, m.name)
-		}
-
-		if n.scope != m.scope {
-			t.Errorf("variable scope mismatch: got %v, want %v", n.scope, m.scope)
-		}
-
-		CompareValues(t, n.value, m.value)
-
 	case ListValueType:
 		n := got.(*ListValue)
 		m := want.(*ListValue)

core/vm.go

@@ -104,6 +104,8 @@ const (
 
 	// InstructionSwap swap the two top items on the stack (1, 2 -> 2, 1)
 	InstructionSwap
+	// InstructionDuplicate push a copy of the item on top of the stack (1 -> 1, 1)
+	InstructionDuplicate
 
 	// InstructionAnd pop two booleans and push true if both are true
 	InstructionAnd
@@ -234,6 +236,8 @@ func (b Bytecode) String() string {
 		return "ACCESS_PROPERTY"
 	case InstructionConcatLists:
 		return "CONCAT_LISTS"
+	case InstructionDuplicate:
+		return "DUPLICATE"
 	}
 	return "UNDEFINED"
 }
@@ -267,6 +271,30 @@ func (c Chunk) String() string {
 	return b.String()
 }
 
+func (c *Chunk) Equals(other *Chunk) bool {
+	if len(c.Bytecode) != len(other.Bytecode) {
+		return false
+	}
+
+	for i, bc := range c.Bytecode {
+		if other.Bytecode[i] != bc {
+			return false
+		}
+	}
+
+	if len(c.Constants) != len(other.Constants) {
+		return false
+	}
+
+	for i := 0; i < len(c.Constants); i++ {
+		if other.Constants[i] != c.Constants[i] {
+			return false
+		}
+	}
+
+	return true
+}
+
 func NewChunk(bytecode []Bytecode, constants []Value) *Chunk {
 	return &Chunk{bytecode, constants}
 }
@@ -327,23 +355,26 @@ type VM struct {
 	chunk *Chunk
 
 	// instruction pointer
-	ip    Pos
+	ip Pos
-	scope Pos
 
 	// global variable storage
-	globals     map[string]Value
+	globals map[string]Value
-	variableEnd Pos
+	// local variable storage
+	scope *Scope
 
 	stack *Stack[Value]
 	call  *Stack[Call]
 }
 
+type Scope struct {
+	current map[string]Value
+	parent  *Scope
+}
+
 type Call struct {
-	chunk       *Chunk
+	chunk *Chunk
-	ip          Pos
+	ip    Pos
-	stackEnd    Pos
+	scope *Scope
-	variableEnd Pos
-	scope       Pos
 }
 
 var DefaultGlobals = map[string]Value{
@@ -355,7 +386,7 @@ var DefaultGlobals = map[string]Value{
 		},
 		func(_ *VM, this Value, v []Value) (Value, error) {
 			println(v[0].String())
-			return nil, nil
+			return &NilValue{}, nil
 		},
 		nil,
 		false,
@@ -368,7 +399,7 @@ var DefaultGlobals = map[string]Value{
 		},
 		func(_ *VM, this Value, v []Value) (Value, error) {
 			print(v[0].String())
-			return nil, nil
+			return &NilValue{}, nil
 		},
 		nil,
 		false,
@@ -630,6 +661,9 @@ func NewVM(chunk *Chunk, stackSize Pos, callstackSize Pos) *VM {
 		call:  NewStack[Call](callstackSize),
 
 		globals: DefaultGlobals,
+		scope: &Scope{
+			current: map[string]Value{},
+		},
 	}
 
 	return vm
@@ -646,24 +680,20 @@ func (vm *VM) Next() bool {
 	case InstructionReturn:
 		if vm.call.Current == 0 {
 			return false
-		} else {
-			v := vm.stack.Pop()
-			c := vm.call.Pop()
-
-			// reset stack current and variable end and scope
-			vm.variableEnd = c.variableEnd
-			vm.stack.Current = c.stackEnd
-			vm.scope = c.scope
-
-			// reset to calling position
-			vm.ip = c.ip
-			vm.chunk = c.chunk
-
-			vm.purgeVars()
-
-			vm.stack.Push(v)
 		}
 
+		v := vm.stack.Pop()
+		c := vm.call.Pop()
+
+		// reset stack current and variable end and scope
+		vm.scope = c.scope
+
+		// reset to calling position
+		vm.ip = c.ip
+		vm.chunk = c.chunk
+
+		vm.stack.Push(v)
+
 	case InstructionPop:
 		vm.stack.Pop()
 
@@ -805,28 +835,21 @@ func (vm *VM) Next() bool {
 		switch f := v.(type) {
 		case *FunctionValue:
 			vm.call.Push(Call{
-				chunk:       vm.chunk,
+				chunk: vm.chunk,
-				ip:          vm.ip,
+				ip:    vm.ip,
-				stackEnd:    vm.stack.Current - Pos(len(f.Params)),
+				scope: vm.scope,
-				variableEnd: vm.variableEnd,
-				scope:       vm.scope,
 			})
 
+			vm.descend()
+
 			for i := len(f.Params) - 1; i >= 0; i-- {
-				p := vm.stack.Current - Pos(len(f.Params)) + Pos(i)
+				vm.addVar(f.Params[i].Name, vm.stack.Pop())
-				vm.stack.items[p] = &VariableValue{
-					f.Params[i].Name,
-					vm.stack.items[p],
-					vm.scope,
-				}
 			}
 
 			if f.Parent != nil {
 				vm.addVar("this", f.Parent)
 			}
 
-			vm.variableEnd = vm.stack.Current
-
 			vm.chunk = f.Chunk
 			vm.ip = 0
 		case *BuiltinFunctionValue:
@@ -868,24 +891,18 @@ func (vm *VM) Next() bool {
 			return false
 		}
 
-		vm.stack.Push(v.value)
+		vm.stack.Push(v)
 
 	case InstructionSetLocal:
-		value := vm.stack.Pop().(Value)
+		value := vm.stack.Peek().Clone()
 		name := vm.GetConstant(vm.NextByte()).(*StringValue).Text
 
-		v := vm.getVar(name)
+		vm.setVar(name, value)
-
-		if v == nil {
-			vm.error(fmt.Sprintf("cannot set local: undefined variable %s", name))
-		}
-
-		v.value = value.Clone()
 
 	case InstructionDeclareLocal:
 		vm.addVar(
 			vm.GetConstant(vm.NextByte()).(*StringValue).Text,
-			vm.stack.Pop().Clone(),
+			vm.stack.Peek().Clone(),
 		)
 
 	case InstructionGetGlobal:
@@ -954,6 +971,9 @@ func (vm *VM) Next() bool {
 
 		vm.stack.Push(r, l)
 
+	case InstructionDuplicate:
+		vm.stack.Push(vm.stack.Peek().Clone())
+
 	case InstructionAccessProperty:
 		source := vm.stack.Pop()
 		property := vm.ReadConstant()
@@ -973,6 +993,7 @@ func (vm *VM) Next() bool {
 		vm.stack.Push(member)
 
 	case InstructionBreakpoint:
+		vm.stack.Push(&NilValue{})
 
 	default:
 		panic("invalid byte code")
@@ -985,11 +1006,9 @@ func (vm *VM) Call(v Value, args []Value) (Value, error) {
 	switch f := v.(type) {
 	case *FunctionValue:
 		vm.call.Push(Call{
-			chunk:       vm.chunk,
+			chunk: vm.chunk,
-			ip:          vm.ip,
+			ip:    vm.ip,
-			stackEnd:    vm.stack.Current,
+			scope: vm.scope,
-			variableEnd: vm.variableEnd,
-			scope:       vm.scope,
 		})
 
 		for i := 0; i < len(f.Params); i++ {
@@ -1000,8 +1019,6 @@ func (vm *VM) Call(v Value, args []Value) (Value, error) {
 			vm.addVar("this", f.Parent)
 		}
 
-		vm.variableEnd = vm.stack.Current
-
 		vm.chunk = f.Chunk
 		vm.ip = 0
 
@@ -1028,6 +1045,14 @@ func (vm *VM) TryNextByte() (Bytecode, error) {
 		return 0, errors.New("there are no more instructions")
 	}
 
+	for int(vm.ip) >= len(vm.chunk.Bytecode) && vm.call.Current > 0 {
+		c := vm.call.Pop()
+
+		vm.ip = c.ip
+		vm.chunk = c.chunk
+		vm.scope = c.scope
+	}
+
 	v := vm.chunk.Bytecode[vm.ip]
 	vm.ip++
 
@@ -1045,53 +1070,55 @@ func (vm *VM) NextByte() Bytecode {
 }
 
 func (vm *VM) ascend() {
-	vm.scope--
+	if vm.scope.parent == nil {
-
-	if vm.scope < 0 {
 		panic("invalid scope")
 	}
 
-	vm.purgeVars()
+	vm.scope = vm.scope.parent
-}
-
-// purgeVars remove all variables not within scope
-func (vm *VM) purgeVars() {
-	for ; vm.variableEnd > 0 && vm.stack.items[vm.variableEnd-1].(*VariableValue).scope > vm.scope; vm.variableEnd-- {
-		vm.stack.Pop()
-	}
 }
 
 func (vm *VM) descend() {
-	vm.scope++
+	old := vm.scope
+
+	vm.scope = &Scope{
+		map[string]Value{},
+		old,
+	}
 }
 
 func (vm *VM) addVar(name string, value Value) {
-	vm.variableEnd++
+	vm.scope.current[name] = value
-	vm.stack.Push(&VariableValue{
-		name,
-		value,
-		vm.scope,
-	})
 }
 
-func (vm *VM) getVar(name string) *VariableValue {
+func (vm *VM) getVar(name string) Value {
-	for i := vm.variableEnd - 1; i >= 0; i-- {
+	s := vm.scope
-		v, ok := vm.stack.items[i].(*VariableValue)
 
-		if !ok {
+	for s != nil {
-			continue
+		if v, ok := s.current[name]; ok {
-		}
-
-		if v.name == name {
 			return v
 		}
+
+		s = s.parent
 	}
 
 	return nil
 }
 
+func (vm *VM) setVar(name string, v Value) {
+	s := vm.scope
+
+	for s != nil {
+		if _, ok := s.current[name]; ok {
+			s.current[name] = v
+			break
+		}
+
+		s = s.parent
+	}
+}
+
 func (vm *VM) HasNext() bool {
-	return vm.ip < Pos(len(vm.chunk.Bytecode))
+	return vm.ip < Pos(len(vm.chunk.Bytecode)) || vm.call.Current > 0
 }
 
 func (vm *VM) GetConstant(id Bytecode) Value {

core/vm_test.go

@@ -95,10 +95,12 @@ func BenchmarkNewVM(b *testing.B) {
 func GetExecutionTestData() map[string]struct {
 	chunk          *Chunk
 	resultingStack []Value
+	resultingScope []map[string]Value
 } {
 	return map[string]struct {
 		chunk          *Chunk
 		resultingStack []Value
+		resultingScope []map[string]Value
 	}{
 		"two_plus_one": {
 			NewChunk([]Bytecode{
@@ -112,6 +114,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&FloatValue{3},
 			},
+			[]map[string]Value{},
 		},
 		"push_constant": {
 			NewChunk(
@@ -125,6 +128,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&FloatValue{1},
 			},
+			[]map[string]Value{},
 		},
 		"push_true": {
 			NewChunk(
@@ -136,6 +140,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&BoolValue{true},
 			},
+			[]map[string]Value{},
 		},
 		"push_false": {
 			NewChunk(
@@ -147,6 +152,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&BoolValue{false},
 			},
+			[]map[string]Value{},
 		},
 		"push_nil": {
 			NewChunk(
@@ -158,6 +164,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&NilValue{},
 			},
+			[]map[string]Value{},
 		},
 		"empty": {
 			NewChunk(
@@ -165,6 +172,7 @@ func GetExecutionTestData() map[string]struct {
 				[]Value{},
 			),
 			[]Value{},
+			[]map[string]Value{},
 		},
 		// (2 + 1) * 5 / (6 - 2)
 		"full_arithmetic": {
@@ -187,6 +195,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&FloatValue{3.75},
 			},
+			[]map[string]Value{},
 		},
 		"equality_true": {
 			NewChunk(
@@ -202,6 +211,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&BoolValue{true},
 			},
+			[]map[string]Value{},
 		},
 		"equality_false": {
 			NewChunk(
@@ -217,6 +227,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&BoolValue{false},
 			},
+			[]map[string]Value{},
 		},
 		"inequality_false": {
 			NewChunk(
@@ -232,6 +243,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&BoolValue{false},
 			},
+			[]map[string]Value{},
 		},
 		"inequality_true": {
 			NewChunk(
@@ -247,6 +259,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&BoolValue{true},
 			},
+			[]map[string]Value{},
 		},
 		"not_true": {
 			NewChunk(
@@ -259,6 +272,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&BoolValue{false},
 			},
+			[]map[string]Value{},
 		},
 		"not_false": {
 			NewChunk(
@@ -271,6 +285,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&BoolValue{true},
 			},
+			[]map[string]Value{},
 		},
 		"jump": {
 			NewChunk(
@@ -286,6 +301,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&FloatValue{1},
 			},
+			[]map[string]Value{},
 		},
 		"jump_false/false": {
 			NewChunk(
@@ -302,6 +318,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&FloatValue{1},
 			},
+			[]map[string]Value{},
 		},
 		"jump_false/true": {
 			NewChunk(
@@ -318,6 +335,7 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&FloatValue{0}, &FloatValue{1},
 			},
+			[]map[string]Value{},
 		},
 		"declare_local": {
 			NewChunk(
@@ -329,11 +347,10 @@ func GetExecutionTestData() map[string]struct {
 					&FloatValue{0}, &StringValue{"a"},
 				},
 			),
-			[]Value{
+			[]Value{&FloatValue{0}},
-				&VariableValue{
+			[]map[string]Value{
-					"a",
+				{
-					&FloatValue{0},
+					"a": &FloatValue{0},
-					0,
 				},
 			},
 		},
@@ -342,18 +359,19 @@ func GetExecutionTestData() map[string]struct {
 				[]Bytecode{
 					InstructionConstant, 0,
 					InstructionDeclareLocal, 1,
+					InstructionPop,
 					InstructionConstant, 2,
 					InstructionSetLocal, 1, // reassign
+					InstructionPop,
 				},
 				[]Value{
 					&FloatValue{0}, &StringValue{"a"}, &FloatValue{1},
 				},
 			),
-			[]Value{
+			[]Value{},
-				&VariableValue{
+			[]map[string]Value{
-					"a",
+				{
-					&FloatValue{1},
+					"a": &FloatValue{1},
-					0,
 				},
 			},
 		},
@@ -362,29 +380,30 @@ func GetExecutionTestData() map[string]struct {
 				[]Bytecode{
 					InstructionConstant, 0,
 					InstructionDeclareLocal, 1,
-					InstructionGetLocal, 1, // reassign
 				},
 				[]Value{
 					&FloatValue{0}, &StringValue{"a"},
 				},
 			),
 			[]Value{
-				&VariableValue{
-					"a",
-					&FloatValue{0},
-					0,
-				},
 				&FloatValue{0},
 			},
+			[]map[string]Value{
+				{
+					"a": &FloatValue{0},
+				},
+			},
 		},
 		"get_reassigned_local": {
 			NewChunk(
 				[]Bytecode{
 					InstructionConstant, 0,
 					InstructionDeclareLocal, 1,
+					InstructionPop,
 					InstructionGetLocal, 1,
 					InstructionConstant, 2,
 					InstructionSetLocal, 1, // reassign
+					InstructionPop,
 					InstructionGetLocal, 1,
 				},
 				[]Value{
@@ -392,26 +411,29 @@ func GetExecutionTestData() map[string]struct {
 				},
 			),
 			[]Value{
-				&VariableValue{
-					"a",
-					&FloatValue{1},
-					0,
-				},
 				&FloatValue{0},
 				&FloatValue{1},
 			},
+			[]map[string]Value{
+				{
+					"a": &FloatValue{1},
+				},
+			},
 		},
 		"variable_scope": {
 			NewChunk(
 				[]Bytecode{
 					InstructionConstant, 0,
 					InstructionDeclareLocal, 1,
+					InstructionPop,
 					InstructionDescend,
 					InstructionConstant, 2,
 					InstructionDeclareLocal, 3,
+					InstructionPop,
 					InstructionDescend,
 					InstructionConstant, 4,
 					InstructionDeclareLocal, 5,
+					InstructionPop,
 					InstructionAscend,
 					InstructionAscend,
 				},
@@ -421,11 +443,10 @@ func GetExecutionTestData() map[string]struct {
 					&FloatValue{2}, &StringValue{"c"},
 				},
 			),
-			[]Value{
+			[]Value{},
-				&VariableValue{
+			[]map[string]Value{
-					"a",
+				{
-					&FloatValue{0},
+					"a": &FloatValue{0},
-					0,
 				},
 			},
 		},
@@ -469,12 +490,14 @@ func GetExecutionTestData() map[string]struct {
 			[]Value{
 				&FloatValue{3},
 			},
+			[]map[string]Value{},
 		},
 		"function_calling_function": {
 			NewChunk(
 				[]Bytecode{
 					InstructionConstant, 3,
 					InstructionDeclareLocal, 4,
+					InstructionPop,
 					InstructionConstant, 0,
 					InstructionConstant, 1,
 					InstructionConstant, 2,
@@ -533,9 +556,11 @@ func GetExecutionTestData() map[string]struct {
 				},
 			),
 			[]Value{
-				&VariableValue{
+				&FloatValue{5},
-					"square",
+			},
-					&FunctionValue{
+			[]map[string]Value{
+				{
+					"square": &FunctionValue{
 						Name: "square",
 						Params: []FunctionParameter{
 							{
@@ -555,9 +580,7 @@ func GetExecutionTestData() map[string]struct {
 							},
 						),
 					},
-					0,
 				},
-				&FloatValue{5},
 			},
 		},
 		"list_concat": {
@@ -590,6 +613,7 @@ func GetExecutionTestData() map[string]struct {
 					},
 				},
 			},
+			[]map[string]Value{},
 		},
 	}
 }

era3.ang

@@ -1,6 +1,10 @@
 
 fn double(a: int) -> int {
-    return 2*a
+    2*a
 }
 
+a := 1
+
+a = 2
+
 println(double(2) == 4)