diff --git a/src/build/Compile.go b/src/build/Compile.go
index a40ab2c..f6f1736 100644
--- a/src/build/Compile.go
+++ b/src/build/Compile.go
@@ -6,7 +6,6 @@ import (
 
 // Compile compiles all the functions.
 func Compile(functions <-chan *Function, errors <-chan error) (map[string]*Function, error) {
-	wg := sync.WaitGroup{}
 	allFunctions := map[string]*Function{}
 
 	for functions != nil || errors != nil {
@@ -25,17 +24,28 @@ func Compile(functions <-chan *Function, errors <-chan error) (map[string]*Funct
 				continue
 			}
 
-			wg.Add(1)
-
-			go func() {
-				defer wg.Done()
-				function.Compile()
-			}()
-
 			allFunctions[function.Name] = function
 		}
 	}
 
+	wg := sync.WaitGroup{}
+
+	for _, function := range allFunctions {
+		wg.Add(1)
+
+		go func() {
+			defer wg.Done()
+			function.Compile()
+		}()
+	}
+
 	wg.Wait()
+
+	for _, function := range allFunctions {
+		if function.Error != nil {
+			return nil, function.Error
+		}
+	}
+
 	return allFunctions, nil
 }
diff --git a/src/build/File.go b/src/build/File.go
new file mode 100644
index 0000000..760bfcc
--- /dev/null
+++ b/src/build/File.go
@@ -0,0 +1,9 @@
+package build
+
+import "git.akyoto.dev/cli/q/src/build/token"
+
+// File represents a single source file.
+type File struct {
+	Tokens token.List
+	Path   string
+}
diff --git a/src/build/Function.go b/src/build/Function.go
index 5fb3f25..18131fd 100644
--- a/src/build/Function.go
+++ b/src/build/Function.go
@@ -14,6 +14,7 @@ import (
 // Function represents a function.
 type Function struct {
 	Name      string
+	File      *File
 	Head      token.List
 	Body      token.List
 	Variables map[string]*Variable
@@ -24,32 +25,60 @@ type Function struct {
 // Compile turns a function into machine code.
 func (f *Function) Compile() {
 	if config.Verbose {
-		ansi.Underline.Println(f.Name)
+		ansi.Bold.Println(f.Name)
 	}
 
-	for _, line := range f.Lines() {
-		if len(line) == 0 {
+	start := 0
+	groupLevel := 0
+
+	for i, t := range f.Body {
+		if start == i && (t.Kind == token.NewLine || t.Kind == token.BlockStart || t.Kind == token.BlockEnd) {
+			start = i + 1
 			continue
 		}
 
-		if config.Verbose {
-			ansi.Dim.Print("[   ] ")
-			fmt.Println(line)
-		}
+		switch t.Kind {
+		case token.NewLine:
+			if groupLevel > 0 {
+				continue
+			}
 
-		err := f.compileInstruction(line)
+			if start != -1 {
+				instruction := f.Body[start:i]
+				err := f.CompileInstruction(instruction)
 
-		if err != nil {
-			ansi.Red.Println(err)
-			return
+				if err != nil {
+					f.Error = err
+					return
+				}
+
+				start = -1
+			}
+
+			start = i + 1
+
+		case token.GroupStart:
+			groupLevel++
+
+		case token.GroupEnd:
+			groupLevel--
+
+		case token.BlockStart:
+			// Add scope
+
+		case token.BlockEnd:
+			// Remove scope
 		}
 	}
 
 	f.Assembler.Return()
 
 	if config.Verbose {
+		fmt.Println()
+		ansi.Bold.Println(f.Name + ".asm")
+
 		for _, x := range f.Assembler.Instructions {
-			ansi.Dim.Print("[asm] ")
+			ansi.Dim.Print("│ ")
 			fmt.Print(x.Mnemonic.String())
 
 			if x.Data != nil {
@@ -61,27 +90,44 @@ func (f *Function) Compile() {
 	}
 }
 
-// compileInstruction compiles a single instruction.
-func (f *Function) compileInstruction(line token.List) error {
-	switch line[0].Kind {
-	case token.Keyword:
+// CompileInstruction compiles a single instruction.
+func (f *Function) CompileInstruction(line token.List) error {
+	if config.Verbose {
+		ansi.Dim.Print("│ ")
+		fmt.Println(line)
+	}
+
+	if line[0].Kind == token.Keyword {
 		switch line[0].Text() {
 		case "return":
 			f.Assembler.Return()
 		}
 
-	case token.Identifier:
-		if len(line) >= 2 && line[1].Kind == token.Define {
+		return nil
+	}
+
+	if line[0].Kind == token.Identifier {
+		if len(line) < 2 {
+			return fmt.Errorf("error to be implemented")
+		}
+
+		if line[1].Kind == token.Define {
 			name := line[0].Text()
 			value := line[2:]
 
+			if len(value) == 0 {
+				return fmt.Errorf("error to be implemented")
+				// return errors.New(errors.MissingAssignmentValue, f.File.Path, f.File.Tokens, f.Cursor)
+			}
+
 			if config.Verbose {
-				ansi.Dim.Printf("[var] ")
-				fmt.Println(name, value)
+				ansi.Dim.Printf("├── var ")
+				fmt.Println(name, "=", value)
 			}
 
 			f.Variables[name] = &Variable{
-				Value:   line[2:],
+				Name:    name,
+				Value:   value,
 				IsConst: true,
 			}
 
@@ -115,7 +161,7 @@ func (f *Function) compileInstruction(line token.List) error {
 					variable, exists := f.Variables[name]
 
 					if !exists {
-						return fmt.Errorf("Unknown identifier '%s'", name)
+						panic("Unknown identifier " + name)
 					}
 
 					if !variable.IsConst {
@@ -142,30 +188,6 @@ func (f *Function) compileInstruction(line token.List) error {
 	return nil
 }
 
-// Lines returns the lines in the function body.
-func (f *Function) Lines() []token.List {
-	var (
-		lines []token.List
-		start = 0
-		i     = 0
-	)
-
-	for i < len(f.Body) {
-		if f.Body[i].Kind == token.NewLine {
-			lines = append(lines, f.Body[start:i])
-			start = i + 1
-		}
-
-		i++
-	}
-
-	if i != start {
-		lines = append(lines, f.Body[start:i])
-	}
-
-	return lines
-}
-
 // String returns the function name.
 func (f *Function) String() string {
 	return f.Name
diff --git a/src/build/Scan.go b/src/build/Scan.go
index 318c598..87f6033 100644
--- a/src/build/Scan.go
+++ b/src/build/Scan.go
@@ -86,6 +86,11 @@ func scanFile(path string, functions chan<- *Function) error {
 
 	tokens := token.Tokenize(contents)
 
+	file := &File{
+		Tokens: tokens,
+		Path:   path,
+	}
+
 	var (
 		i           = 0
 		groupLevel  = 0
@@ -216,6 +221,7 @@ func scanFile(path string, functions chan<- *Function) error {
 
 		functions <- &Function{
 			Name:      tokens[nameStart].Text(),
+			File:      file,
 			Head:      tokens[paramsStart:bodyStart],
 			Body:      tokens[bodyStart : i+1],
 			Variables: map[string]*Variable{},
diff --git a/src/build/Variable.go b/src/build/Variable.go
index 14cece9..46190e2 100644
--- a/src/build/Variable.go
+++ b/src/build/Variable.go
@@ -4,6 +4,7 @@ import "git.akyoto.dev/cli/q/src/build/token"
 
 // Variable represents a variable in a function.
 type Variable struct {
+	Name    string
 	Value   token.List
 	IsConst bool
 }
diff --git a/src/build/token/Token.go b/src/build/token/Token.go
index 78d6005..7c10db2 100644
--- a/src/build/token/Token.go
+++ b/src/build/token/Token.go
@@ -1,5 +1,7 @@
 package token
 
+import "fmt"
+
 // Token represents a single element in a source file.
 // The characters that make up an identifier are grouped into a single token.
 // This makes parsing easier and allows us to do better syntax checks.
@@ -9,6 +11,11 @@ type Token struct {
 	Bytes    []byte
 }
 
+// String creates a human readable representation for debugging purposes.
+func (t Token) String() string {
+	return fmt.Sprintf("%s %s", t.Kind, t.Text())
+}
+
 // Text returns the token text.
 func (t Token) Text() string {
 	return string(t.Bytes)
diff --git a/src/errors/CompileErrors.go b/src/errors/CompileErrors.go
new file mode 100644
index 0000000..2c5ac46
--- /dev/null
+++ b/src/errors/CompileErrors.go
@@ -0,0 +1,5 @@
+package errors
+
+var (
+	MissingAssignmentValue = &Base{"Missing assignment value"}
+)