diff --git a/src/build/ast/AST.go b/src/build/ast/AST.go
index 7def683..1c8f6dd 100644
--- a/src/build/ast/AST.go
+++ b/src/build/ast/AST.go
@@ -1,63 +1,6 @@
 package ast
 
-import (
-	"fmt"
-
-	"git.akyoto.dev/cli/q/src/build/expression"
-	"git.akyoto.dev/cli/q/src/build/token"
-)
+import "fmt"
 
 type Node fmt.Stringer
 type AST []Node
-
-type Assign struct {
-	Value    *expression.Expression
-	Name     token.Token
-	Operator token.Token
-}
-
-func (node *Assign) String() string {
-	return fmt.Sprintf("(= %s %s)", node.Name.Text(), node.Value)
-}
-
-type Call struct {
-	Expression *expression.Expression
-}
-
-func (node *Call) String() string {
-	return node.Expression.String()
-}
-
-type Define struct {
-	Value *expression.Expression
-	Name  token.Token
-}
-
-func (node *Define) String() string {
-	return fmt.Sprintf("(= %s %s)", node.Name.Text(), node.Value)
-}
-
-type If struct {
-	Condition *expression.Expression
-	Body      AST
-}
-
-func (node *If) String() string {
-	return fmt.Sprintf("(if %s %s)", node.Condition, node.Body)
-}
-
-type Loop struct {
-	Body AST
-}
-
-func (node *Loop) String() string {
-	return fmt.Sprintf("(loop %s)", node.Body)
-}
-
-type Return struct {
-	Value *expression.Expression
-}
-
-func (node *Return) String() string {
-	return fmt.Sprintf("(return %s)", node.Value)
-}
diff --git a/src/build/ast/Assign.go b/src/build/ast/Assign.go
new file mode 100644
index 0000000..daee95d
--- /dev/null
+++ b/src/build/ast/Assign.go
@@ -0,0 +1,19 @@
+package ast
+
+import (
+	"fmt"
+
+	"git.akyoto.dev/cli/q/src/build/expression"
+	"git.akyoto.dev/cli/q/src/build/token"
+)
+
+// Assign represents an assignment to an existing variable or memory location.
+type Assign struct {
+	Value    *expression.Expression
+	Name     token.Token
+	Operator token.Token
+}
+
+func (node *Assign) String() string {
+	return fmt.Sprintf("(= %s %s)", node.Name.Text(), node.Value)
+}
diff --git a/src/build/ast/Call.go b/src/build/ast/Call.go
new file mode 100644
index 0000000..d7825b3
--- /dev/null
+++ b/src/build/ast/Call.go
@@ -0,0 +1,12 @@
+package ast
+
+import "git.akyoto.dev/cli/q/src/build/expression"
+
+// Call represents a function call.
+type Call struct {
+	Expression *expression.Expression
+}
+
+func (node *Call) String() string {
+	return node.Expression.String()
+}
diff --git a/src/build/ast/Define.go b/src/build/ast/Define.go
new file mode 100644
index 0000000..6751491
--- /dev/null
+++ b/src/build/ast/Define.go
@@ -0,0 +1,18 @@
+package ast
+
+import (
+	"fmt"
+
+	"git.akyoto.dev/cli/q/src/build/expression"
+	"git.akyoto.dev/cli/q/src/build/token"
+)
+
+// Define represents a variable definition.
+type Define struct {
+	Value *expression.Expression
+	Name  token.Token
+}
+
+func (node *Define) String() string {
+	return fmt.Sprintf("(= %s %s)", node.Name.Text(), node.Value)
+}
diff --git a/src/build/ast/If.go b/src/build/ast/If.go
new file mode 100644
index 0000000..47d98d4
--- /dev/null
+++ b/src/build/ast/If.go
@@ -0,0 +1,17 @@
+package ast
+
+import (
+	"fmt"
+
+	"git.akyoto.dev/cli/q/src/build/expression"
+)
+
+// If represents an if statement.
+type If struct {
+	Condition *expression.Expression
+	Body      AST
+}
+
+func (node *If) String() string {
+	return fmt.Sprintf("(if %s %s)", node.Condition, node.Body)
+}
diff --git a/src/build/ast/Loop.go b/src/build/ast/Loop.go
new file mode 100644
index 0000000..5b0dc33
--- /dev/null
+++ b/src/build/ast/Loop.go
@@ -0,0 +1,12 @@
+package ast
+
+import "fmt"
+
+// Loop represents a block of repeatable statements.
+type Loop struct {
+	Body AST
+}
+
+func (node *Loop) String() string {
+	return fmt.Sprintf("(loop %s)", node.Body)
+}
diff --git a/src/build/ast/Return.go b/src/build/ast/Return.go
new file mode 100644
index 0000000..a56520f
--- /dev/null
+++ b/src/build/ast/Return.go
@@ -0,0 +1,16 @@
+package ast
+
+import (
+	"fmt"
+
+	"git.akyoto.dev/cli/q/src/build/expression"
+)
+
+// Return represents a return statement.
+type Return struct {
+	Value *expression.Expression
+}
+
+func (node *Return) String() string {
+	return fmt.Sprintf("(return %s)", node.Value)
+}