Implemented source tracking and type checking

src/compiler/Compile.go

@@ -6,6 +6,7 @@ import (
 	"git.urbach.dev/cli/q/src/build"
 	"git.urbach.dev/cli/q/src/core"
 	"git.urbach.dev/cli/q/src/scanner"
+	"git.urbach.dev/cli/q/src/types"
 )
 
 // Compile waits for the scan to finish and compiles all functions.
@@ -16,13 +17,43 @@ func Compile(b *build.Build) (*core.Environment, error) {
 		return nil, err
 	}
 
+	// Check for existence of `init`
+	init, exists := all.Functions["core.init"]
+
+	if !exists {
+		return nil, MissingInitFunction
+	}
+
 	// Check for existence of `main`
-	_, exists := all.Functions["main.main"]
+	_, exists = all.Functions["main.main"]
 
 	if !exists {
 		return nil, MissingMainFunction
 	}
 
+	// Resolve types
+	for _, f := range all.Functions {
+		f.Type = &types.Function{
+			Input:  make([]types.Type, len(f.Input)),
+			Output: make([]types.Type, len(f.Output)),
+		}
+
+		for i, input := range f.Input {
+			input.Typ = types.Parse(input.Source[1:], f.File.Bytes)
+			f.Type.Input[i] = input.Typ
+		}
+
+		for i, output := range f.Output {
+			if len(output.Source) > 1 {
+				output.Typ = types.Parse(output.Source[1:], f.File.Bytes)
+			} else {
+				output.Typ = types.Parse(output.Source, f.File.Bytes)
+			}
+
+			f.Type.Output[i] = output.Typ
+		}
+	}
+
 	compileFunctions(maps.Values(all.Functions))
 
 	for _, f := range all.Functions {
@@ -32,7 +63,7 @@ func Compile(b *build.Build) (*core.Environment, error) {
 	}
 
 	if b.ShowSSA {
-		showSSA(maps.Values(all.Functions))
+		showSSA(init)
 	}
 
 	return all, nil

src/compiler/errors.go

@@ -3,5 +3,6 @@ package compiler
 import "git.urbach.dev/cli/q/src/errors"
 
 var (
+	MissingInitFunction = errors.String("Missing init function")
 	MissingMainFunction = errors.String("Missing main function")
 )

src/compiler/showSSA.go

@@ -2,16 +2,15 @@ package compiler
 
 import (
 	"fmt"
-	"iter"
 
 	"git.urbach.dev/cli/q/src/core"
 	"git.urbach.dev/go/color/ansi"
 )
 
 // showSSA shows the SSA IR.
-func showSSA(functions iter.Seq[*core.Function]) {
+func showSSA(root *core.Function) {
-	for f := range functions {
+	root.EachDependency(make(map[*core.Function]bool), func(f *core.Function) {
-		ansi.Bold.Printf("%s:\n", f.UniqueName)
+		ansi.Yellow.Printf("%s:\n", f.UniqueName)
 
 		for i, block := range f.Blocks {
 			if i != 0 {
@@ -19,8 +18,13 @@ func showSSA(functions iter.Seq[*core.Function]) {
 			}
 
 			for i, instr := range block.Instructions {
-				fmt.Printf("t%d = %s\n", i, instr.String())
+				ansi.Dim.Printf("%-4d", i)
-			}
+				fmt.Printf("%-40s", instr.String())
+				ansi.Cyan.Printf("%-30s", instr.Type().Name())
+				ansi.Dim.Printf("%s\n", f.File.Bytes[instr.Start():instr.End()])
 			}
 		}
+
+		fmt.Println()
+	})
 }

src/core/CheckDeadCode.go

@@ -8,7 +8,7 @@ import (
 func (f *Function) CheckDeadCode() error {
 	for instr := range f.Values {
 		if instr.IsConst() && instr.Alive() == 0 {
-			return errors.New(&UnusedValue{Value: instr.String()}, f.File, instr.Token().Position)
+			return errors.New(&UnusedValue{Value: instr.String()}, f.File, instr.Start())
 		}
 	}
 

src/core/Compile.go

@@ -6,7 +6,7 @@ import (
 	"git.urbach.dev/cli/q/src/asm"
 	"git.urbach.dev/cli/q/src/cpu"
 	"git.urbach.dev/cli/q/src/ssa"
-	"git.urbach.dev/cli/q/src/token"
+	"git.urbach.dev/cli/q/src/types"
 )
 
 // Compile turns a function into machine code.
@@ -18,12 +18,35 @@ func (f *Function) Compile() {
 			continue
 		}
 
-		f.Identifiers[input.Name] = f.AppendRegister(i + extra)
+		array, isArray := input.Typ.(*types.Array)
 
-		if input.TypeTokens[0].Kind == token.ArrayStart {
+		if isArray {
-			extra++
+			pointer := &ssa.Parameter{
-			f.Identifiers[input.Name+".length"] = f.AppendRegister(i + extra)
+				Index:  uint8(i + extra),
+				Name:   input.Name,
+				Typ:    &types.Pointer{To: array.Of},
+				Source: input.Source,
 			}
+
+			f.Append(pointer)
+			f.Identifiers[pointer.Name] = pointer
+			extra++
+
+			length := &ssa.Parameter{
+				Index:  uint8(i + extra),
+				Name:   input.Name + ".len",
+				Typ:    types.AnyInt,
+				Source: input.Source,
+			}
+
+			f.Append(length)
+			f.Identifiers[length.Name] = length
+			continue
+		}
+
+		input.Index = uint8(i + extra)
+		f.Append(input)
+		f.Identifiers[input.Name] = input
 	}
 
 	for instr := range f.Body.Instructions {
@@ -49,15 +72,15 @@ func (f *Function) Compile() {
 	for instr := range f.Values {
 		switch instr := instr.(type) {
 		case *ssa.Call:
-			f.mv(instr.Args[1:], f.CPU.Call)
+			f.mv(instr.Arguments[1:], f.CPU.Call)
 
-			switch arg := instr.Args[0].(type) {
+			switch arg := instr.Arguments[0].(type) {
 			case *ssa.Function:
 				f.Assembler.Instructions = append(f.Assembler.Instructions, &asm.Call{Label: arg.UniqueName})
 			}
 
 		case *ssa.Syscall:
-			f.mv(instr.Args, f.CPU.Syscall)
+			f.mv(instr.Arguments, f.CPU.Syscall)
 			f.Assembler.Append(&asm.Syscall{})
 
 		case *ssa.Return:

src/core/CompileReturn.go

@@ -16,9 +16,8 @@ func (f *Function) CompileReturn(tokens token.List) error {
 	}
 
 	f.Append(&ssa.Return{
-		Arguments: ssa.Arguments{
+		Arguments: []ssa.Value{value},
-			Args: []ssa.Value{value},
+		Source:    ssa.Source(tokens),
-		},
 	})
 
 	return nil

src/core/Evaluate.go

@@ -8,6 +8,7 @@ import (
 	"git.urbach.dev/cli/q/src/expression"
 	"git.urbach.dev/cli/q/src/ssa"
 	"git.urbach.dev/cli/q/src/token"
+	"git.urbach.dev/cli/q/src/types"
 )
 
 // Evaluate converts an expression to an SSA value.
@@ -26,8 +27,8 @@ func (f *Function) Evaluate(expr *expression.Expression) (ssa.Value, error) {
 				}
 
 				f.Dependencies.Add(function)
-				v := f.AppendFunction(function.UniqueName)
+				v := f.AppendFunction(function.UniqueName, function.Type)
-				v.Source = expr.Token
+				v.Source = ssa.Source(expr.Source)
 				return v, nil
 			}
 
@@ -41,14 +42,14 @@ func (f *Function) Evaluate(expr *expression.Expression) (ssa.Value, error) {
 			}
 
 			v := f.AppendInt(number)
-			v.Source = expr.Token
+			v.Source = ssa.Source(expr.Source)
 			return v, nil
 
 		case token.String:
 			data := expr.Token.Bytes(f.File.Bytes)
 			data = Unescape(data)
 			v := f.AppendBytes(data)
-			v.Source = expr.Token
+			v.Source = ssa.Source(expr.Source)
 			return v, nil
 		}
 
@@ -65,7 +66,13 @@ func (f *Function) Evaluate(expr *expression.Expression) (ssa.Value, error) {
 
 			if funcName == "len" {
 				identifier := children[1].String(f.File.Bytes)
-				return f.Identifiers[identifier+".length"], nil
+				length, exists := f.Identifiers[identifier+".len"]
+
+				if !exists {
+					return nil, errors.New(&UnknownIdentifier{Name: identifier + ".len"}, f.File, expr.Token.Position)
+				}
+
+				return length, nil
 			}
 
 			if funcName == "syscall" {
@@ -87,19 +94,37 @@ func (f *Function) Evaluate(expr *expression.Expression) (ssa.Value, error) {
 		}
 
 		if isSyscall {
-			v := f.Append(&ssa.Syscall{
+			syscall := &ssa.Syscall{
-				Arguments: ssa.Arguments{Args: args},
+				Arguments: args,
-				HasToken:  ssa.HasToken{Source: expr.Token},
+				Source:    ssa.Source(expr.Source),
-			})
+			}
 
-			return v, nil
+			return f.Append(syscall), nil
 		} else {
-			v := f.Append(&ssa.Call{
+			name := args[0].(*ssa.Function).UniqueName
-				Arguments: ssa.Arguments{Args: args},
+			fn := f.All.Functions[name]
-				HasToken:  ssa.HasToken{Source: expr.Token},
+			parameters := args[1:]
-			})
 
-			return v, nil
+			if len(parameters) != len(fn.Input) {
+				return nil, errors.New(&ParameterCountMismatch{Function: name, Count: len(parameters), ExpectedCount: len(fn.Input)}, f.File, expr.Source[0].Position)
+			}
+
+			for i, param := range parameters {
+				if !types.Is(param.Type(), fn.Input[i].Typ) {
+					return nil, errors.New(&TypeMismatch{
+						Encountered:   param.Type().Name(),
+						Expected:      fn.Input[i].Typ.Name(),
+						ParameterName: fn.Input[i].Name,
+					}, f.File, param.Start())
+				}
+			}
+
+			call := &ssa.Call{
+				Arguments: args,
+				Source:    ssa.Source(expr.Source),
+			}
+
+			return f.Append(call), nil
 		}
 
 	case token.Dot:
@@ -113,8 +138,8 @@ func (f *Function) Evaluate(expr *expression.Expression) (ssa.Value, error) {
 		}
 
 		f.Dependencies.Add(function)
-		v := f.AppendFunction(function.UniqueName)
+		v := f.AppendFunction(function.UniqueName, function.Type)
-		v.Source = expr.Children[1].Token
+		v.Source = ssa.Source(expr.Source)
 		return v, nil
 	}
 

src/core/Function.go

@@ -9,6 +9,7 @@ import (
 	"git.urbach.dev/cli/q/src/set"
 	"git.urbach.dev/cli/q/src/ssa"
 	"git.urbach.dev/cli/q/src/token"
+	"git.urbach.dev/cli/q/src/types"
 )
 
 // Function is the smallest unit of code.
@@ -17,14 +18,15 @@ type Function struct {
 	Name         string
 	UniqueName   string
 	File         *fs.File
-	Input        []*Parameter
+	Input        []*ssa.Parameter
-	Output       []*Parameter
+	Output       []*ssa.Parameter
 	Body         token.List
 	Identifiers  map[string]ssa.Value
 	All          *Environment
 	Dependencies set.Ordered[*Function]
 	Assembler    asm.Assembler
 	CPU          *cpu.CPU
+	Type         *types.Function
 	Err          error
 }
 

src/core/Function_test.go

@@ -18,8 +18,4 @@ func TestFunction(t *testing.T) {
 	assert.False(t, main.IsExtern())
 	assert.Equal(t, main.UniqueName, "main.main")
 	assert.Equal(t, main.String(), main.UniqueName)
-
-	write, exists := env.Functions["io.write"]
-	assert.True(t, exists)
-	write.Output[0].Type()
 }

src/core/Parameter.go

@@ -1,18 +0,0 @@
-package core
-
-import (
-	"git.urbach.dev/cli/q/src/token"
-	"git.urbach.dev/cli/q/src/types"
-)
-
-// Parameter is an input or output parameter in a function.
-type Parameter struct {
-	Name       string
-	TypeTokens token.List
-	typ        types.Type
-}
-
-// Type returns the data type of the parameter.
-func (p *Parameter) Type() types.Type {
-	return p.typ
-}

src/core/errors.go

@@ -12,6 +12,43 @@ var (
 	InvalidRune       = errors.String("Invalid rune")
 )
 
+// ParameterCountMismatch error is created when the number of provided parameters doesn't match the function signature.
+type ParameterCountMismatch struct {
+	Function      string
+	Count         int
+	ExpectedCount int
+}
+
+func (err *ParameterCountMismatch) Error() string {
+	if err.Count > err.ExpectedCount {
+		return fmt.Sprintf("Too many parameters in '%s' function call", err.Function)
+	}
+
+	return fmt.Sprintf("Not enough parameters in '%s' function call", err.Function)
+}
+
+// TypeMismatch represents an error where a type requirement was not met.
+type TypeMismatch struct {
+	Encountered   string
+	Expected      string
+	ParameterName string
+	IsReturn      bool
+}
+
+func (err *TypeMismatch) Error() string {
+	subject := "type"
+
+	if err.IsReturn {
+		subject = "return type"
+	}
+
+	if err.ParameterName != "" {
+		return fmt.Sprintf("Expected parameter '%s' of %s '%s' (encountered '%s')", err.ParameterName, subject, err.Expected, err.Encountered)
+	}
+
+	return fmt.Sprintf("Expected %s '%s' instead of '%s'", subject, err.Expected, err.Encountered)
+}
+
 // UnknownIdentifier represents unknown identifiers.
 type UnknownIdentifier struct {
 	Name        string

src/expression/Expression.go

@@ -11,6 +11,7 @@ type Expression struct {
 	Parent     *Expression
 	Children   []*Expression
 	Token      token.Token
+	Source     token.List
 	precedence int8
 }
 

src/expression/Parse.go

@@ -7,12 +7,13 @@ import (
 )
 
 // Parse generates an expression tree from tokens.
-func Parse(tokens []token.Token) *Expression {
+func Parse(tokens token.List) *Expression {
 	var (
 		cursor        *Expression
 		root          *Expression
 		groupLevel    = 0
 		groupPosition = 0
+		cursorStart   = 0
 	)
 
 	for i, t := range tokens {
@@ -38,6 +39,7 @@ func Parse(tokens []token.Token) *Expression {
 				parameters := NewList(tokens[groupPosition:i])
 				node := New()
 				node.Token.Position = tokens[groupPosition].Position
+				node.Source = tokens[groupPosition:i]
 
 				switch t.Kind {
 				case token.GroupEnd:
@@ -72,6 +74,7 @@ func Parse(tokens []token.Token) *Expression {
 				continue
 			}
 
+			group.Source = tokens[groupPosition:i]
 			group.precedence = math.MaxInt8
 
 			if cursor == nil {
@@ -79,6 +82,7 @@ func Parse(tokens []token.Token) *Expression {
 					cursor = New()
 					cursor.Token.Position = tokens[groupPosition].Position
 					cursor.Token.Kind = token.Array
+					cursor.Source = tokens[groupPosition:i]
 					cursor.precedence = precedence(token.Array)
 					cursor.AddChild(group)
 					root = cursor
@@ -88,6 +92,7 @@ func Parse(tokens []token.Token) *Expression {
 				}
 			} else {
 				cursor.AddChild(group)
+				cursor.Source = tokens[cursorStart : i+1]
 			}
 
 			continue
@@ -100,9 +105,13 @@ func Parse(tokens []token.Token) *Expression {
 		if t.Kind == token.Identifier || t.Kind == token.Number || t.Kind == token.String || t.Kind == token.Rune {
 			if cursor != nil {
 				node := NewLeaf(t)
+				node.Source = tokens[i : i+1]
+				cursor.Source = tokens[cursorStart : i+1]
 				cursor.AddChild(node)
 			} else {
 				cursor = NewLeaf(t)
+				cursorStart = i
+				cursor.Source = tokens[i : i+1]
 				root = cursor
 			}
 
@@ -115,12 +124,15 @@ func Parse(tokens []token.Token) *Expression {
 
 		if cursor == nil {
 			cursor = NewLeaf(t)
+			cursorStart = i
+			cursor.Source = tokens[i : i+1]
 			cursor.precedence = precedence(t.Kind)
 			root = cursor
 			continue
 		}
 
 		node := NewLeaf(t)
+		node.Source = tokens[i : i+1]
 		node.precedence = precedence(t.Kind)
 
 		if cursor.Token.IsOperator() {
@@ -131,6 +143,7 @@ func Parse(tokens []token.Token) *Expression {
 				if len(cursor.Children) == numOperands(cursor.Token.Kind) {
 					cursor.LastChild().InsertAbove(node)
 				} else {
+					cursor.Source = tokens[cursorStart : i+1]
 					cursor.AddChild(node)
 				}
 			} else {
@@ -169,5 +182,9 @@ func Parse(tokens []token.Token) *Expression {
 		cursor = node
 	}
 
+	if root != nil {
+		root.Source = tokens
+	}
+
 	return root
 }

src/scanner/scanSignature.go

@@ -4,6 +4,7 @@ import (
 	"git.urbach.dev/cli/q/src/core"
 	"git.urbach.dev/cli/q/src/errors"
 	"git.urbach.dev/cli/q/src/fs"
+	"git.urbach.dev/cli/q/src/ssa"
 	"git.urbach.dev/cli/q/src/token"
 )
 
@@ -94,9 +95,9 @@ func scanSignature(file *fs.File, tokens token.List, i int, delimiter token.Kind
 			return nil, i, errors.New(MissingType, file, param[0].End())
 		}
 
-		function.Input = append(function.Input, &core.Parameter{
+		function.Input = append(function.Input, &ssa.Parameter{
 			Name:   param[0].String(file.Bytes),
-			TypeTokens: param[1:],
+			Source: ssa.Source(param),
 		})
 	}
 
@@ -127,18 +128,19 @@ func scanSignature(file *fs.File, tokens token.List, i int, delimiter token.Kind
 		}
 
 		if len(param) == 1 {
-			function.Output = append(function.Output, &core.Parameter{
+			function.Output = append(function.Output, &ssa.Parameter{
 				Name:   "",
-				TypeTokens: param,
+				Source: ssa.Source(param),
 			})
 		} else {
-			function.Output = append(function.Output, &core.Parameter{
+			function.Output = append(function.Output, &ssa.Parameter{
 				Name:   param[0].String(file.Bytes),
-				TypeTokens: param[1:],
+				Source: ssa.Source(param),
 			})
 		}
 
 		errorPos = param[len(param)-1].End() + 1
 	}
+
 	return function, i, nil
 }

src/ssa/Arguments.go

@@ -1,20 +1,18 @@
 package ssa
 
-type Arguments struct {
+type Arguments []Value
-	Args []Value
-}
 
-func (v *Arguments) Dependencies() []Value {
+func (v Arguments) Dependencies() []Value {
-	return v.Args
+	return v
 }
 
 func (a Arguments) Equals(b Arguments) bool {
-	if len(a.Args) != len(b.Args) {
+	if len(a) != len(b) {
 		return false
 	}
 
-	for i := range a.Args {
+	for i := range a {
-		if !a.Args[i].Equals(b.Args[i]) {
+		if !a[i].Equals(b[i]) {
 			return false
 		}
 	}

src/ssa/BinaryOperation.go

@@ -5,6 +5,7 @@ import (
 
 	"git.urbach.dev/cli/q/src/expression"
 	"git.urbach.dev/cli/q/src/token"
+	"git.urbach.dev/cli/q/src/types"
 )
 
 type BinaryOperation struct {
@@ -12,7 +13,7 @@ type BinaryOperation struct {
 	Right Value
 	Op    token.Kind
 	Liveness
-	HasToken
+	Source
 }
 
 func (v *BinaryOperation) Dependencies() []Value {
@@ -26,10 +27,6 @@ func (a *BinaryOperation) Equals(v Value) bool {
 		return false
 	}
 
-	if a.Source.Kind != b.Source.Kind {
-		return false
-	}
-
 	if !a.Left.Equals(b.Left) {
 		return false
 	}
@@ -48,3 +45,7 @@ func (v *BinaryOperation) IsConst() bool {
 func (v *BinaryOperation) String() string {
 	return fmt.Sprintf("%s %s %s", v.Left, expression.Operators[v.Op].Symbol, v.Right)
 }
+
+func (v *BinaryOperation) Type() types.Type {
+	return v.Left.Type()
+}

src/ssa/Bytes.go

@@ -1,11 +1,16 @@
 package ssa
 
-import "bytes"
+import (
+	"bytes"
+	"strconv"
+
+	"git.urbach.dev/cli/q/src/types"
+)
 
 type Bytes struct {
 	Bytes []byte
 	Liveness
-	HasToken
+	Source
 }
 
 func (v *Bytes) Dependencies() []Value {
@@ -27,5 +32,9 @@ func (v *Bytes) IsConst() bool {
 }
 
 func (v *Bytes) String() string {
-	return string(v.Bytes)
+	return strconv.Quote(string(v.Bytes))
+}
+
+func (v *Bytes) Type() types.Type {
+	return types.String
 }

src/ssa/Call.go

@@ -1,11 +1,15 @@
 package ssa
 
-import "fmt"
+import (
+	"fmt"
+
+	"git.urbach.dev/cli/q/src/types"
+)
 
 type Call struct {
 	Arguments
 	Liveness
-	HasToken
+	Source
 }
 
 func (a *Call) Equals(v Value) bool {
@@ -23,5 +27,15 @@ func (v *Call) IsConst() bool {
 }
 
 func (v *Call) String() string {
-	return fmt.Sprintf("call%v", v.Args)
+	return fmt.Sprintf("%s(%v)", v.Arguments[0], v.Arguments[1:])
+}
+
+func (v *Call) Type() types.Type {
+	typ := v.Arguments[0].(*Function).Typ
+
+	if len(typ.Output) == 0 {
+		return types.Void
+	}
+
+	return typ.Output[0]
 }

src/ssa/Function.go

@@ -1,9 +1,12 @@
 package ssa
 
+import "git.urbach.dev/cli/q/src/types"
+
 type Function struct {
 	UniqueName string
+	Typ        *types.Function
 	Liveness
-	HasToken
+	Source
 }
 
 func (v *Function) Dependencies() []Value {
@@ -27,3 +30,7 @@ func (v *Function) IsConst() bool {
 func (v *Function) String() string {
 	return v.UniqueName
 }
+
+func (v *Function) Type() types.Type {
+	return v.Typ
+}

src/ssa/HasToken.go

@@ -1,11 +0,0 @@
-package ssa
-
-import "git.urbach.dev/cli/q/src/token"
-
-type HasToken struct {
-	Source token.Token
-}
-
-func (v *HasToken) Token() token.Token {
-	return v.Source
-}

src/ssa/IR.go

@@ -1,5 +1,7 @@
 package ssa
 
+import "git.urbach.dev/cli/q/src/types"
+
 // IR is a list of basic blocks.
 type IR struct {
 	Blocks []*Block
@@ -39,16 +41,9 @@ func (f *IR) AppendInt(x int) *Int {
 	return v
 }
 
-// AppendRegister adds a new register value to the last block.
-func (f *IR) AppendRegister(index int) *Parameter {
-	v := &Parameter{Index: uint8(index)}
-	f.Append(v)
-	return v
-}
-
 // AppendFunction adds a new function value to the last block.
-func (f *IR) AppendFunction(name string) *Function {
+func (f *IR) AppendFunction(name string, typ *types.Function) *Function {
-	v := &Function{UniqueName: name}
+	v := &Function{UniqueName: name, Typ: typ}
 	f.Append(v)
 	return v
 }

src/ssa/Int.go

@@ -2,12 +2,14 @@ package ssa
 
 import (
 	"fmt"
+
+	"git.urbach.dev/cli/q/src/types"
 )
 
 type Int struct {
 	Int int
 	Liveness
-	HasToken
+	Source
 }
 
 func (v *Int) Dependencies() []Value {
@@ -31,3 +33,7 @@ func (v *Int) IsConst() bool {
 func (v *Int) String() string {
 	return fmt.Sprintf("%d", v.Int)
 }
+
+func (v *Int) Type() types.Type {
+	return types.AnyInt
+}

src/ssa/Parameter.go

@@ -1,11 +1,17 @@
 package ssa
 
-import "fmt"
+import (
+	"fmt"
+
+	"git.urbach.dev/cli/q/src/types"
+)
 
 type Parameter struct {
 	Index uint8
+	Name  string
+	Typ   types.Type
 	Liveness
-	HasToken
+	Source
 }
 
 func (v *Parameter) Dependencies() []Value {
@@ -27,5 +33,9 @@ func (v *Parameter) IsConst() bool {
 }
 
 func (v *Parameter) String() string {
-	return fmt.Sprintf("arg[%d]", v.Index)
+	return fmt.Sprintf("in[%d]", v.Index)
+}
+
+func (v *Parameter) Type() types.Type {
+	return v.Typ
 }

src/ssa/Return.go

@@ -1,10 +1,14 @@
 package ssa
 
-import "fmt"
+import (
+	"fmt"
+
+	"git.urbach.dev/cli/q/src/types"
+)
 
 type Return struct {
 	Arguments
-	HasToken
+	Source
 }
 
 func (a *Return) AddUse(user Value) { panic("return is not a value") }
@@ -17,12 +21,12 @@ func (a *Return) Equals(v Value) bool {
 		return false
 	}
 
-	if len(a.Args) != len(b.Args) {
+	if len(a.Arguments) != len(b.Arguments) {
 		return false
 	}
 
-	for i := range a.Args {
+	for i := range a.Arguments {
-		if !a.Args[i].Equals(b.Args[i]) {
+		if !a.Arguments[i].Equals(b.Arguments[i]) {
 			return false
 		}
 	}
@@ -35,5 +39,9 @@ func (v *Return) IsConst() bool {
 }
 
 func (v *Return) String() string {
-	return fmt.Sprintf("return %v", v.Args)
+	return fmt.Sprintf("return %v", v.Arguments)
+}
+
+func (v *Return) Type() types.Type {
+	return types.Void
 }

src/ssa/Source.go

@@ -0,0 +1,13 @@
+package ssa
+
+import "git.urbach.dev/cli/q/src/token"
+
+type Source token.List
+
+func (v Source) Start() token.Position {
+	return v[0].Position
+}
+
+func (v Source) End() token.Position {
+	return v[len(v)-1].End()
+}

src/ssa/Syscall.go

@@ -1,11 +1,15 @@
 package ssa
 
-import "fmt"
+import (
+	"fmt"
+
+	"git.urbach.dev/cli/q/src/types"
+)
 
 type Syscall struct {
 	Arguments
 	Liveness
-	HasToken
+	Source
 }
 
 func (a *Syscall) Equals(v Value) bool {
@@ -23,5 +27,9 @@ func (v *Syscall) IsConst() bool {
 }
 
 func (v *Syscall) String() string {
-	return fmt.Sprintf("syscall%v", v.Args)
+	return fmt.Sprintf("syscall(%v)", v.Arguments)
+}
+
+func (v *Syscall) Type() types.Type {
+	return types.Any
 }

src/ssa/Value.go

@@ -1,13 +1,18 @@
 package ssa
 
-import "git.urbach.dev/cli/q/src/token"
+import (
+	"git.urbach.dev/cli/q/src/token"
+	"git.urbach.dev/cli/q/src/types"
+)
 
 type Value interface {
 	AddUse(Value)
 	Alive() int
 	Dependencies() []Value
+	End() token.Position
 	Equals(Value) bool
 	IsConst() bool
 	String() string
-	Token() token.Token
+	Start() token.Position
+	Type() types.Type
 }

src/types/Common.go

@@ -17,6 +17,7 @@ var (
 	UInt32     = &Base{name: "uint32", size: 4}
 	UInt16     = &Base{name: "uint16", size: 2}
 	UInt8      = &Base{name: "uint8", size: 1}
+	Void       = &Base{name: "void", size: 0}
 )
 
 var (

src/types/Function.go

@@ -0,0 +1,47 @@
+package types
+
+import "strings"
+
+// Function transforms inputs to new outputs.
+type Function struct {
+	Input  []Type
+	Output []Type
+}
+
+// Name returns the type name.
+func (f *Function) Name() string {
+	builder := strings.Builder{}
+	builder.WriteString("(")
+
+	for i, input := range f.Input {
+		builder.WriteString(input.Name())
+
+		if i != len(f.Input)-1 {
+			builder.WriteString(", ")
+		}
+	}
+
+	builder.WriteString(")")
+
+	if len(f.Output) == 0 {
+		return builder.String()
+	}
+
+	builder.WriteString(" -> (")
+
+	for i, output := range f.Output {
+		builder.WriteString(output.Name())
+
+		if i != len(f.Output)-1 {
+			builder.WriteString(",")
+		}
+	}
+
+	builder.WriteString(")")
+	return builder.String()
+}
+
+// Size returns the total size in bytes.
+func (f *Function) Size() int {
+	return 8
+}

src/types/Parse.go

@@ -0,0 +1,71 @@
+package types
+
+import (
+	"git.urbach.dev/cli/q/src/token"
+)
+
+// Parse returns the type with the given tokens or `nil` if it doesn't exist.
+func Parse[T ~[]token.Token](tokens T, source []byte) Type {
+	if tokens[0].Kind == token.Mul {
+		to := tokens[1:]
+		typ := Parse(to, source)
+
+		if typ == Any {
+			return AnyPointer
+		}
+
+		return &Pointer{To: typ}
+	}
+
+	if len(tokens) >= 2 && tokens[0].Kind == token.ArrayStart && tokens[1].Kind == token.ArrayEnd {
+		to := tokens[2:]
+		typ := Parse(to, source)
+
+		if typ == Any {
+			return AnyArray
+		}
+
+		return &Array{Of: typ}
+	}
+
+	if tokens[0].Kind != token.Identifier {
+		return nil
+	}
+
+	switch tokens[0].String(source) {
+	case "int":
+		return Int
+	case "int64":
+		return Int64
+	case "int32":
+		return Int32
+	case "int16":
+		return Int16
+	case "int8":
+		return Int8
+	case "uint":
+		return UInt
+	case "uint64":
+		return UInt64
+	case "uint32":
+		return UInt32
+	case "uint16":
+		return UInt16
+	case "uint8":
+		return UInt8
+	case "byte":
+		return Byte
+	case "bool":
+		return Bool
+	case "float":
+		return Float
+	case "float64":
+		return Float64
+	case "float32":
+		return Float32
+	case "any":
+		return Any
+	default:
+		return nil
+	}
+}