improve errors, add warnings, add some compile-time optimizations, fix variables, make sure conditionals and loops get booleans, affirm types, keep variables to a single type

cli/main.go

@@ -14,8 +14,9 @@ type Context struct {
 }
 
 type RunCmd struct {
-	Bytecode bool   `name:"bytecode" short:"c" help:"Run file as if it's bytecode"`
+	IgnoreWarnings bool   `name:"ignore-warnings" help:"Ignore warning messages"`
-	File     string `arg:"" name:"file" help:"File to read program from" type:"existingfile"`
+	Bytecode       bool   `name:"bytecode" short:"c" help:"Run file as if it's bytecode"`
+	File           string `arg:"" name:"file" help:"File to read program from" type:"existingfile"`
 }
 
 // WorkingDirectoryResolver resolves imports relative to the working directory
@@ -30,9 +31,9 @@ func (r *WorkingDirectoryResolver) Resolve(path string) (core.Node, error) {
 		return nil, err
 	}
 
-	str := string(f)
+	src := string(f)
 
-	l := core.NewLexer(str)
+	l := core.NewLexer(src)
 
 	tokens, err := l.Tokenize()
 	if err != nil {
@@ -107,7 +108,7 @@ func (cmd *RunCmd) Run(ctx *Context) error {
 		if ctx.Debug {
 			log.Println("Initialized compiler")
 		}
-		c := core.NewCompiler()
+		c := core.NewCompiler([]rune(src))
 
 		if ctx.Debug {
 			log.Println("Setting imports resolver")
@@ -125,11 +126,19 @@ func (cmd *RunCmd) Run(ctx *Context) error {
 		if err != nil {
 			var e core.CompilerError
 			if errors.As(err, &e) {
-				log.Fatal(e.Format([]rune(src)))
+				log.Fatal(e.Format())
 			}
 			log.Fatal(err)
 		}
 
+		// if there were non-critical warnings, report them
+		if !cmd.IgnoreWarnings && len(c.Warnings) != 0 {
+			for _, warning := range c.Warnings {
+				log.Println(warning.Format())
+			}
+			log.Fatal("compiler reported warning(s) (ignore warnings with the --ignore-warnings option)")
+		}
+
 		chunk = c.Chunk
 	} else {
 		if ctx.Debug {
@@ -216,7 +225,7 @@ func (cmd *CompileCmd) Run(ctx *Context) error {
 		log.Println("Initialized compiler")
 	}
 
-	c := core.NewCompiler()
+	c := core.NewCompiler([]rune(src))
 
 	if ctx.Debug {
 		log.Println("Setting import resolver")
@@ -235,11 +244,18 @@ func (cmd *CompileCmd) Run(ctx *Context) error {
 	if err != nil {
 		var e core.CompilerError
 		if errors.As(err, &e) {
-			log.Fatal(e.Format([]rune(src)))
+			log.Fatal(e.Format())
 		}
 		log.Fatal(err)
 	}
 
+	// if there were non-critical warnings, report them
+	if len(c.Warnings) != 0 {
+		for _, warning := range c.Warnings {
+			log.Println(warning.Format())
+		}
+	}
+
 	if ctx.Debug {
 		log.Println("Registering GOB types")
 	}

core/all_test.go

@@ -22,7 +22,7 @@ func GetAllTestCases() map[string]AllTestCase {
 			},
 		},
 		"func": {
-			"func sum(a: number, b: number) {\n\treturn a + b\n}\nsum(1, 2)",
+			"func sum(a: number, b: number) number {\n\treturn a + b\n}\n_ = sum(1, 2)",
 			[]Value{
 				&VariableValue{
 					"sum",
@@ -54,6 +54,21 @@ func GetAllTestCases() map[string]AllTestCase {
 				},
 			},
 		},
+		"list": {
+			"a := [1, 2]",
+			[]Value{
+				&VariableValue{
+					"a",
+					&ListValue{
+						[]Value{
+							&NumberValue{1},
+							&NumberValue{2},
+						},
+					},
+					0,
+				},
+			},
+		},
 	}
 }
 
@@ -84,7 +99,7 @@ func TestAll(t *testing.T) {
 			}
 
 			t.Log("Initializing compiler")
-			c := NewCompiler()
+			c := NewCompiler([]rune(tc.src))
 
 			t.Log("Compiling parse tree")
 			err = c.Compile(tree)
@@ -119,7 +134,7 @@ func BenchmarkAll(b *testing.B) {
 				p := NewParser(tokens)
 				tree, _ := p.Parse()
 
-				c := NewCompiler()
+				c := NewCompiler([]rune(tc.src))
 				_ = c.Compile(tree)
 
 				vm := NewVM(c.Chunk, 256, 256)

core/compiler.go

@@ -12,6 +12,8 @@ type Compiler struct {
 
 	imports  map[string]Node
 	resolver ImportsResolver
+	source   []rune
+	Warnings []CompilerError
 
 	stack *Stack[LocalVariable]
 }
@@ -29,25 +31,29 @@ type LocalVariable struct {
 type CompilerError struct {
 	Description string
 	Causer      Node
+	Source      []rune
 }
 
 func (e CompilerError) Error() string {
 	return e.Description
 }
 
-func (e CompilerError) Format(src []rune) string {
+func (e CompilerError) Format() string {
 	b := strings.Builder{}
 
+	src := e.Source
+
 	b.WriteString(e.Description)
-	b.WriteString("\n")
 
 	// highlight offending area
 	start, end := e.Causer.Bounds()
 
+	lineEnd := 0
 	lineStart := 0
 	line := 1
 	pos := 0
-	for i := Pos(0); i < start; i++ {
+
+	for i := Pos(0); i <= start; i++ {
 		pos++
 
 		if src[i] == '\n' {
@@ -57,37 +63,51 @@ func (e CompilerError) Format(src []rune) string {
 		}
 	}
 
-	lineEnd := lineStart
+	for lineEnd < int(end) {
-	for lineEnd < len(src) {
+		b.WriteString("\n")
-		lineEnd++
+		lineEnd = lineStart
-		if src[lineEnd] == '\n' {
+		for lineEnd < len(src) {
-			break
+			lineEnd++
+			if src[lineEnd] == '\n' {
+				break
+			}
 		}
+
+		begin := max(0, int(start)-lineStart)
+		length := int(min(end, Pos(lineEnd)) - max(start, Pos(lineStart)))
+
+		lineDescriptor := fmt.Sprintf("%d:%d~%d",
+			line,
+			begin,
+			begin+length,
+		)
+
+		b.WriteString(lineDescriptor)
+		b.WriteString(" | ")
+
+		b.WriteString(string(src[lineStart+1 : lineEnd]))
+		b.WriteString("\n")
+
+		b.WriteString(strings.Repeat(" ", len(lineDescriptor)))
+		b.WriteString("  ")
+		b.WriteString(strings.Repeat(" ", max(int(start)-lineStart, 0)))
+		b.WriteString(strings.Repeat("^", length))
+
+		lineStart = lineEnd
+		line++
 	}
-
-	lineDescriptor := fmt.Sprintf("%d:%d~%d", line, pos, int(end-start)+pos)
-
-	b.WriteString(lineDescriptor)
-	b.WriteString("\t | ")
-
-	b.WriteString(string(src[lineStart+1 : lineEnd]))
-	b.WriteString("\n")
-
-	b.WriteString(strings.Repeat(" ", len(lineDescriptor)))
-	b.WriteString("\t   ")
-	b.WriteString(strings.Repeat(" ", int(start)-lineStart-1))
-	b.WriteString(strings.Repeat("^", int(end-start)))
-
 	return b.String()
 }
 
-func NewCompiler() *Compiler {
+func NewCompiler(source []rune) *Compiler {
 	c := &Compiler{
 		NewChunk(make([]Bytecode, 0), make([]Value, 0)),
 		0,
 		0,
 		make(map[string]Node),
 		nil,
+		source,
+		[]CompilerError{},
 		NewStack[LocalVariable](256),
 	}
 
@@ -202,20 +222,29 @@ func (c *Compiler) Compile(tree Node) error {
 		c.add(InstructionNil)
 
 	case BlockNodeType:
-		c.descend()
+		c.addDescend()
 		for _, n := range tree.(*BlockNode).statements {
 			err := c.Compile(n)
 			if err != nil {
 				return err
 			}
 		}
-		c.ascend()
+		c.addAscend()
 
 	case ConditionalNodeType:
 		n := tree.(*ConditionalNode)
 
+		// make sure condition is boolean
+		sig, err := c.deduceSignature(n.condition)
+		if err != nil {
+			return err
+		}
+		if sig.Type() != TypeBoolean {
+			return c.error(fmt.Sprintf("condition cannot give non-boolean type %s", sig), n.condition)
+		}
+
 		// the stack should have whether the condition was truthful
-		err := c.Compile(n.condition)
+		err = c.Compile(n.condition)
 		if err != nil {
 			return err
 		}
@@ -256,8 +285,17 @@ func (c *Compiler) Compile(tree Node) error {
 	case LoopNodeType:
 		n := tree.(*LoopNode)
 
+		// make sure condition is boolean
+		sig, err := c.deduceSignature(n.condition)
+		if err != nil {
+			return err
+		}
+		if sig.Type() != TypeBoolean {
+			return c.error(fmt.Sprintf("cannot loop over value of type %s; requires boolean", sig), n.condition)
+		}
+
 		conditionPos := c.ip
-		err := c.Compile(n.condition)
+		err = c.Compile(n.condition)
 		if err != nil {
 			return err
 		}
@@ -307,6 +345,14 @@ 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)
+		}
+
 		for i, arg := range n.args {
 			sig, err := c.deduceSignature(arg)
 			if err != nil {
@@ -365,6 +411,10 @@ func (c *Compiler) Compile(tree Node) error {
 			c.registerVar(p.Name, p.Signature)
 		}
 
+		if err := c.affirmReturnSignature(n.logic, n.yield); err != nil {
+			return err
+		}
+
 		err = c.Compile(n.logic)
 		if err != nil {
 			return err
@@ -377,6 +427,7 @@ func (c *Compiler) Compile(tree Node) error {
 		mc.Constants[fi] = &FunctionValue{
 			n.name,
 			n.parameters,
+			n.yield,
 			c.Chunk,
 			nil,
 		}
@@ -493,18 +544,13 @@ func (c *Compiler) deduceSignature(tree Node) (TypeSignature, error) {
 		return &NumberSignature{}, nil
 	case ReferenceNodeType:
 		n := tree.(*ReferenceNode)
-		if c.isGlobal(n.name) {
+		sig, err := c.getVarSignature(n.name, n)
-			return SignatureOf(DefaultGlobals[n.name]), nil
+		if err != nil {
+			return nil, err
 		}
 
-		for i := c.stack.Current - 1; i >= 0; i-- {
+		return sig, nil
-			v := c.stack.items[i]
-			if v.name == n.name {
-				return v.signature, nil
-			}
-		}
 
-		return nil, c.error(fmt.Sprintf("variable %s not defined", n.name), n)
 	case BooleanNodeType:
 		return &BooleanSignature{}, nil
 	case NilNodeType:
@@ -564,7 +610,7 @@ func (c *Compiler) deduceSignature(tree Node) (TypeSignature, error) {
 			}
 		case BinaryAnd, BinaryOr:
 			if l.Type() != TypeBoolean {
-				return nil, c.error(fmt.Sprintf("cannot perform binary %s on type %s", l, n.BinaryOperation), n)
+				return nil, c.error(fmt.Sprintf("cannot perform binary %s on non-boolean type %s", n.BinaryOperation, l), n)
 			}
 
 			return &BooleanSignature{}, nil
@@ -572,7 +618,7 @@ func (c *Compiler) deduceSignature(tree Node) (TypeSignature, error) {
 			return &BooleanSignature{}, nil
 		case BinaryLess, BinaryGreater, BinaryLessEqual, BinaryGreaterEqual:
 			if l.Type() != TypeNumber {
-				return nil, c.error(fmt.Sprintf("cannot perform number comparison (%s) on type %s", l, n.BinaryOperation), n)
+				return nil, c.error(fmt.Sprintf("cannot perform number comparison (%s) on non-number type %s", n.BinaryOperation, l), n)
 			}
 
 			return &BooleanSignature{}, nil
@@ -588,15 +634,30 @@ func (c *Compiler) deduceSignature(tree Node) (TypeSignature, error) {
 
 		switch sig.Type() {
 		case TypeString:
-			return SignatureOf(StringPrototype[n.property]), nil
+			v := StringPrototype[n.property]
+			if v == nil {
+				return nil, c.error(fmt.Sprintf("string has no property %s", n.property), tree)
+			}
+
+			return SignatureOf(v), nil
 		case TypeList:
-			return SignatureOf(ListPrototype[n.property]), nil
+			v := ListPrototype[n.property]
+			if v == nil {
+				return nil, c.error(fmt.Sprintf("list has no property %s", n.property), tree)
+			}
+
+			return SignatureOf(v), nil
 		case TypeObject:
 			if v, ok := ObjectPrototype[n.property]; ok {
 				return SignatureOf(v), nil
 			}
 
-			return sig.(*ObjectSignature).Members[n.property], nil
+			v := sig.(*ObjectSignature).Members[n.property]
+			if v == nil {
+				return nil, c.error(fmt.Sprintf("object has no property %s", n.property), tree)
+			}
+
+			return v, nil
 
 		default:
 			return nil, c.error(fmt.Sprintf("cannot access property from value of type %s", sig), n)
@@ -674,14 +735,31 @@ func (c *Compiler) deduceSignature(tree Node) (TypeSignature, error) {
 	}
 }
 
+func (c *Compiler) getVarSignature(name string, causer Node) (TypeSignature, error) {
+	if c.isGlobal(name) {
+		return SignatureOf(DefaultGlobals[name]), nil
+	}
+
+	for i := c.stack.Current - 1; i >= 0; i-- {
+		v := c.stack.items[i]
+		if v.name == name {
+			return v.signature, nil
+		}
+	}
+
+	return nil, c.error(fmt.Sprintf("variable %s not defined", name), causer)
+}
+
 func (c *Compiler) affirmReturnSignature(tree Node, sig TypeSignature) error {
 	switch tree.Type() {
 	case BlockNodeType:
+		c.descend()
 		for _, stmt := range tree.(*BlockNode).statements {
 			if err := c.affirmReturnSignature(stmt, sig); err != nil {
 				return err
 			}
 		}
+		c.ascend()
 
 	case ReturnNodeType:
 		n := tree.(*ReturnNode)
@@ -713,6 +791,33 @@ func (c *Compiler) affirmReturnSignature(tree Node, sig TypeSignature) error {
 		if err := c.affirmReturnSignature(n.do, sig); err != nil {
 			return err
 		}
+
+	case AssignNodeType:
+		n := tree.(*AssignNode)
+
+		if !n.declare {
+			prev, err := c.getVarSignature(n.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 of type %s", prev, sig), n.value)
+			}
+
+			return nil
+		}
+
+		sig, err := c.deduceSignature(n.value)
+		if err != nil {
+			return err
+		}
+		c.registerVar(n.name, sig)
 	default:
 	}
 
@@ -902,6 +1007,10 @@ func (c *Compiler) ascend() {
 
 	for ; c.stack.Current > 0 && c.stack.Peek().scope > int(c.scope); c.stack.Pop() {
 	}
+}
+
+func (c *Compiler) addAscend() {
+	c.ascend()
 
 	if c.scope != 0 {
 		c.add(InstructionAscend)
@@ -910,6 +1019,10 @@ func (c *Compiler) ascend() {
 
 func (c *Compiler) descend() {
 	c.scope++
+}
+
+func (c *Compiler) addDescend() {
+	c.descend()
 	if c.scope != 1 {
 		c.add(InstructionDescend)
 	}
@@ -919,9 +1032,14 @@ func (c *Compiler) error(msg string, causer Node) CompilerError {
 	return CompilerError{
 		msg,
 		causer,
+		c.source,
 	}
 }
 
+func (c *Compiler) warn(msg string, causer Node) {
+	c.Warnings = append(c.Warnings, c.error(msg, causer))
+}
+
 func (c *Compiler) resolveImport(path string) Node {
 	if chunk, ok := c.imports[path]; ok {
 		return chunk

core/compiler_test.go

@@ -6,7 +6,7 @@ import (
 )
 
 func TestNewCompiler(t *testing.T) {
-	c := NewCompiler()
+	c := NewCompiler([]rune{})
 
 	if c == nil {
 		t.Fatal("NewCompiler returned nil")
@@ -23,7 +23,7 @@ func TestNewCompiler(t *testing.T) {
 
 func BenchmarkNewCompiler(b *testing.B) {
 	for i := 0; i < b.N; i++ {
-		_ = NewCompiler()
+		_ = NewCompiler([]rune{})
 	}
 }
 
@@ -267,51 +267,52 @@ func GetCompileTestData() map[string]CompileTestData {
 				&NumberValue{3},
 			},
 		},
-		"sum_function": {&BlockNode{
+		"sum_function": {
-			[]Node{
+			&BlockNode{
-				&AssignNode{
+				[]Node{
-					"sum",
+					&AssignNode{
-					&FunctionNode{
 						"sum",
-						[]FunctionParameter{
+						&FunctionNode{
-							{
+							"sum",
-								"a",
+							[]FunctionParameter{
-								&NumberSignature{},
+								{
+									"a",
+									&NumberSignature{},
+								},
+								{
+									"b",
+									&NumberSignature{},
+								},
 							},
-							{
+							&NumberSignature{},
-								"b",
+							&BlockNode{
-								&NumberSignature{},
+								[]Node{
-							},
+									&ReturnNode{
-						},
+										&BinaryNode{
-						&NumberSignature{},
+											BinaryAddition,
-						&BlockNode{
+											&ReferenceNode{
-							[]Node{
+												"a",
-								&ReturnNode{
+												0, 0,
-									&BinaryNode{
+											},
-										BinaryAddition,
+											&ReferenceNode{
-										&ReferenceNode{
+												"b",
-											"a",
+												0, 0,
-											0, 0,
+											},
-										},
-										&ReferenceNode{
-											"b",
 											0, 0,
 										},
 										0, 0,
 									},
-									0, 0,
 								},
+								0, 0,
 							},
 							0, 0,
 						},
+						true,
 						0, 0,
 					},
-					true,
-					0, 0,
 				},
+				0, 0,
 			},
-			0, 0,
-		},
 			[]Value{
 				&VariableValue{
 					"sum",
@@ -328,6 +329,7 @@ func GetCompileTestData() map[string]CompileTestData {
 								&NumberSignature{},
 							},
 						},
+						&NumberSignature{},
 						NewChunk(
 							[]Bytecode{
 								InstructionDescend,
@@ -355,7 +357,7 @@ func GetCompileTestData() map[string]CompileTestData {
 						&FunctionNode{
 							"a",
 							[]FunctionParameter{},
-							&NilSignature{},
+							&NumberSignature{},
 							&BlockNode{
 								[]Node{
 									&AssignNode{
@@ -400,6 +402,7 @@ func GetCompileTestData() map[string]CompileTestData {
 					&FunctionValue{
 						"a",
 						[]FunctionParameter{},
+						&NumberSignature{},
 						NewChunk(
 							[]Bytecode{
 								InstructionDescend,
@@ -419,6 +422,54 @@ func GetCompileTestData() map[string]CompileTestData {
 				},
 			},
 		},
+		"two_lists": {
+			tree: &BlockNode{
+				statements: []Node{
+					&AssignNode{
+						name: "a",
+						value: &ListNode{
+							items: []Node{
+								&NumberNode{value: 1},
+								&NumberNode{value: 2},
+							},
+						},
+						declare: true,
+					},
+					&AssignNode{
+						name: "b",
+						value: &ListNode{
+							items: []Node{
+								&StringNode{value: "Hello"},
+								&StringNode{value: "world"},
+							},
+						},
+						declare: true,
+					},
+				},
+			},
+			expectedStack: []Value{
+				&VariableValue{
+					name: "a",
+					value: &ListValue{
+						Items: []Value{
+							&NumberValue{1},
+							&NumberValue{2},
+						},
+					},
+					scope: 0,
+				},
+				&VariableValue{
+					name: "b",
+					value: &ListValue{
+						Items: []Value{
+							&StringValue{"Hello"},
+							&StringValue{"world"},
+						},
+					},
+					scope: 0,
+				},
+			},
+		},
 	}
 }
 
@@ -448,7 +499,7 @@ func TestCompile(t *testing.T) {
 	for name, testCase := range data {
 		t.Run(name, func(t *testing.T) {
 			t.Log("Initializing compiler")
-			c := NewCompiler()
+			c := NewCompiler([]rune(testCase.tree.String()))
 
 			t.Log("Compiling node tree")
 			err := c.Compile(testCase.tree)
@@ -477,7 +528,7 @@ func BenchmarkCompile(b *testing.B) {
 	for name, testCase := range data {
 		b.Run(name, func(b *testing.B) {
 			for i := 0; i < b.N; i++ {
-				c := NewCompiler()
+				c := NewCompiler([]rune{})
 				_ = c.Compile(testCase.tree)
 			}
 		})
@@ -487,7 +538,7 @@ func BenchmarkCompile(b *testing.B) {
 func TestCompiler_AddU16(t *testing.T) {
 	for i := 0; i <= 0xffff; i++ {
 		t.Run(fmt.Sprint(i), func(t *testing.T) {
-			c := NewCompiler()
+			c := NewCompiler([]rune{})
 			c.addU16(uint16(i))
 
 			if c.Chunk.Bytecode[0] != Bytecode(i>>8) {
@@ -521,7 +572,7 @@ func TestCompiler_CleanStack(t *testing.T) {
 		}
 
 		t.Run(name, func(t *testing.T) {
-			c := NewCompiler()
+			c := NewCompiler([]rune(tc.tree.String()))
 			err := c.Compile(tc.tree)
 			if err != nil {
 				t.Fatalf("Compiling failed: %v", err)

core/nodes.go

@@ -439,6 +439,10 @@ func (n ConditionalNode) Type() NodeType {
 }
 
 func (n ConditionalNode) String() string {
+	if n.otherwise == nil {
+		return fmt.Sprintf("if %s then %s", n.condition.String(), n.do.String())
+	}
+
 	return fmt.Sprintf("if %s then %s otheriwise %s", n.condition.String(), n.do.String(), n.otherwise.String())
 }
 

core/parser.go

@@ -148,7 +148,7 @@ func (p *Parser) factor() (Node, error) {
 			(*p.prev).Lexeme[1 : len((*p.prev).Lexeme)-1],
 			(*p.prev).Lexeme,
 			p.prev.Start,
-			p.prev.Length,
+			p.prev.Start + p.prev.Length,
 		}, nil
 
 	case TokenNumber:
@@ -162,7 +162,7 @@ func (p *Parser) factor() (Node, error) {
 		return &NumberNode{
 			num,
 			p.prev.Start,
-			p.prev.Length,
+			p.prev.Start + p.prev.Length,
 		}, nil
 
 	case TokenHexadecimal:
@@ -184,14 +184,14 @@ func (p *Parser) factor() (Node, error) {
 		return &BooleanNode{
 			true,
 			p.prev.Start,
-			p.prev.Length,
+			p.prev.Start + p.prev.Length,
 		}, nil
 	case TokenFalse:
 		p.advance()
 		return &BooleanNode{
 			false,
 			p.prev.Start,
-			p.prev.Length,
+			p.prev.Start + p.prev.Length,
 		}, nil
 
 	case TokenNil:

core/types.go

@@ -53,11 +53,35 @@ func SignatureOf(v Value) TypeSignature {
 	case *BoolValue:
 		return &BooleanSignature{}
 	case *ListValue:
-		return &ListSignature{}
+		// try to deduce contents type
+		var contains TypeSignature
+
+		for _, p := range t.Items {
+			sig := SignatureOf(p)
+			if contains == nil {
+				contains = sig
+			} else if !contains.Matches(sig) {
+				contains = &AnySignature{}
+				break
+			}
+		}
+
+		return &ListSignature{
+			contains,
+		}
 	case *ObjectValue:
 		return &ObjectSignature{}
 	case *FunctionValue:
-		return &FunctionSignature{}
+		params := make([]TypeSignature, len(t.Params))
+
+		for i, p := range t.Params {
+			params[i] = p.Signature
+		}
+
+		return &FunctionSignature{
+			params,
+			t.Yield,
+		}
 	case *BuiltinFunctionValue:
 		return t.Signature
 	}
@@ -267,8 +291,11 @@ func (s *FunctionSignature) String() string {
 		b.WriteString(t.String())
 	}
 
-	b.WriteString(") ")
+	b.WriteString(")")
-	b.WriteString(s.Out.String())
+	if s.Out.Type() != TypeNil {
+		b.WriteString(" ")
+		b.WriteString(s.Out.String())
+	}
 
 	return b.String()
 }

core/values.go

@@ -234,6 +234,7 @@ var ObjectPrototype = map[string]Value{
 			return &NilValue{}, nil
 		},
 		nil,
+		false,
 	},
 }
 
@@ -338,6 +339,17 @@ var StringPrototype = map[string]*BuiltinFunctionValue{
 			return GoToValue(out), nil
 		},
 		nil,
+		true,
+	},
+	"length": {
+		Name: "length",
+		Signature: &FunctionSignature{
+			[]TypeSignature{},
+			&NumberSignature{},
+		},
+		F: func(vm *VM, this Value, _ []Value) (Value, error) {
+			return GoToValue(len(this.(*StringValue).Text)), nil
+		},
 	},
 }
 
@@ -392,7 +404,7 @@ func (v *ListValue) Equals(other Value) bool {
 		return false
 	}
 
-	for i, item := range l.Items {
+	for i, item := range v.Items {
 		if !item.Equals(l.Items[i]) {
 			return false
 		}
@@ -413,6 +425,7 @@ var ListPrototype = map[string]*BuiltinFunctionValue{
 			return &NilValue{}, nil
 		},
 		nil,
+		false,
 	},
 	"at": {
 		"at",
@@ -433,6 +446,7 @@ var ListPrototype = map[string]*BuiltinFunctionValue{
 			return items[index], nil
 		},
 		nil,
+		false,
 	},
 	"length": {
 		"length",
@@ -444,6 +458,7 @@ var ListPrototype = map[string]*BuiltinFunctionValue{
 			return GoToValue(len(this.(*ListValue).Items)), nil
 		},
 		nil,
+		false,
 	},
 	"map": {
 		"map",
@@ -484,6 +499,7 @@ var ListPrototype = map[string]*BuiltinFunctionValue{
 			return list, nil
 		},
 		nil,
+		false,
 	},
 	"reduce": {
 		"reduce",
@@ -516,6 +532,7 @@ var ListPrototype = map[string]*BuiltinFunctionValue{
 			return sum, nil
 		},
 		nil,
+		false,
 	},
 }
 
@@ -542,6 +559,7 @@ func (v *ListValue) Clone() Value {
 type FunctionValue struct {
 	Name   string
 	Params []FunctionParameter
+	Yield  TypeSignature
 	Chunk  *Chunk
 	Parent Value
 }
@@ -572,6 +590,7 @@ func (v *FunctionValue) Clone() Value {
 	return &FunctionValue{
 		v.Name,
 		v.Params,
+		v.Yield,
 		v.Chunk,
 		v.Parent,
 	}
@@ -582,6 +601,7 @@ type BuiltinFunctionValue struct {
 	Signature *FunctionSignature
 	F         func(*VM, Value, []Value) (Value, error)
 	Parent    Value
+	Constant  bool
 }
 
 func (v *BuiltinFunctionValue) Type() ValueType {
@@ -611,6 +631,7 @@ func (v *BuiltinFunctionValue) Clone() Value {
 		v.Signature,
 		v.F,
 		v.Parent,
+		v.Constant,
 	}
 }
 

core/values_test.go

@@ -78,6 +78,32 @@ func CompareValues(t *testing.T, got Value, want Value) {
 
 		CompareValues(t, n.value, m.value)
 
+	case ListValueType:
+		n := got.(*ListValue)
+		m := want.(*ListValue)
+
+		if len(n.Items) != len(m.Items) {
+			t.Fatalf("list items length mismatch: got %d, want %d", len(n.Items), len(m.Items))
+		}
+
+		for i, v := range n.Items {
+			t.Logf("comparing list items #%d: got %s, want %s", i, v, m.Items[i])
+			CompareValues(t, v, m.Items[i])
+		}
+
+	case ObjectValueType:
+		n := got.(*ObjectValue)
+		m := want.(*ObjectValue)
+
+		if len(n.Members) != len(m.Members) {
+			t.Fatalf("object members count mismatch: got %d, want %d", len(n.Members), len(m.Members))
+		}
+
+		for k, v := range n.Members {
+			t.Logf("comparing object member %s: got %s, want %s", k, v, m.Members[k])
+			CompareValues(t, v, m.Members[k])
+		}
+
 	default:
 		panic("unimplemented comparison")
 	}

core/vm.go

@@ -311,6 +311,7 @@ var DefaultGlobals = map[string]Value{
 			return nil, nil
 		},
 		nil,
+		false,
 	},
 	"print": &BuiltinFunctionValue{
 		"print",
@@ -323,6 +324,7 @@ var DefaultGlobals = map[string]Value{
 			return nil, nil
 		},
 		nil,
+		false,
 	},
 	"format": &BuiltinFunctionValue{
 		"format",
@@ -356,6 +358,7 @@ var DefaultGlobals = map[string]Value{
 			return GoToValue(b.String()), nil
 		},
 		nil,
+		true,
 	},
 	"char": &BuiltinFunctionValue{
 		"char",
@@ -372,6 +375,7 @@ var DefaultGlobals = map[string]Value{
 			}, nil
 		},
 		nil,
+		true,
 	},
 	"assertEq": &BuiltinFunctionValue{
 		"assertEq",
@@ -393,6 +397,7 @@ var DefaultGlobals = map[string]Value{
 			return &NilValue{}, nil
 		},
 		nil,
+		false,
 	},
 	"assertNotEq": &BuiltinFunctionValue{
 		"assertNotEq",
@@ -414,6 +419,7 @@ var DefaultGlobals = map[string]Value{
 			return &NilValue{}, nil
 		},
 		nil,
+		false,
 	},
 	"str": &BuiltinFunctionValue{
 		"str",
@@ -425,6 +431,21 @@ var DefaultGlobals = map[string]Value{
 			return GoToValue(args[0].String()), nil
 		},
 		nil,
+		true,
+	},
+	"type": &BuiltinFunctionValue{
+		Name: "type",
+		Signature: &FunctionSignature{
+			In:  []TypeSignature{&AnySignature{}},
+			Out: &StringSignature{},
+		},
+		F: func(vm *VM, this Value, args []Value) (Value, error) {
+			v := args[0]
+			sig := SignatureOf(v)
+
+			return GoToValue(sig.String()), nil
+		},
+		Constant: true,
 	},
 	"exit": &BuiltinFunctionValue{
 		"exit",
@@ -437,6 +458,7 @@ var DefaultGlobals = map[string]Value{
 			return &NilValue{}, nil
 		},
 		nil,
+		false,
 	},
 }
 

lib/testing.ang

@@ -1,8 +1,17 @@
 
+NAMESPACE := ""
+
+func namespace(name: string, test: func()) {
+    NAMESPACE = name
+    test()
+}
+
 func assertEqual(a: any, b: any) {
     if a != b {
         write(format("assertion error: % should (but doesn't) equal %", [a, b]))
         exit(1)
+    } else if env("DEBUG") != "" {
+        write(format("assertion success: % equals %", [a, b]))
     }
 }
 
@@ -10,5 +19,7 @@ func assertNotEqual(a: any, b: any) {
     if a == b {
         write(format("assertion error: % shouldn't (but does) equal %", [a, b]))
         exit(1)
+    } else if env("DEBUG") != "" {
+        write(format("assertion success: % doesn't equal %", [a, b]))
     }
 }

test_all.sh

@@ -1,26 +1,24 @@
 #!/bin/zsh
 
 echo '=== Building CLI ==='
-(
+cd cli || exit 1
-  cd cli || exit 1
+if ! go build .; then
-  if ! go build .; then
+  echo "=== Had error building CLI ==="
-    echo "=== Had error building CLI ==="
+  exit 1
-    exit 1
+else
-  else
+  echo "=+= Successfully built CLI =+="
-    echo "=+= Successfully built CLI =+="
+fi
-  fi
+cd ..
-)
 
 echo "=== Running go core tests ==="
-(
+cd core || exit 1
-  cd core || exit 1
+if ! go test .; then
-  if ! go test .; then
+  echo "=x= Core testing failed =x= "
-    echo "=x= Core testing failed =x= "
+  exit 1
-    exit 1
+else
-  else
+  echo "=+= Successfully ran core tests =+="
-    echo "=+= Successfully ran core tests =+="
+fi
-  fi
+cd ..
-)
 
 errors=()
 

tests/types.ang

@@ -0,0 +1,8 @@
+
+assertEq(type(1), "number")
+assertEq(type("Hello"), "string")
+assertEq(type(true), "boolean")
+
+# lists
+assertEq(type(["Hello", "world"]), "list[string]")
+assertEq(type([0, 1]), "list[number]")

wasm/wasm.go

@@ -77,7 +77,7 @@ func run(_ js.Value, args []js.Value) interface{} {
 
 	log.Printf("Parsed tree: %s", tree.String())
 
-	compiler := core.NewCompiler()
+	compiler := core.NewCompiler([]rune(source))
 
 	compiler.SetImportsResolver(&JsResolver{
 		resolver,