diff --git a/ast/ast.go b/ast/ast.go
new file mode 100644
index 0000000..f044b82
--- /dev/null
+++ b/ast/ast.go
@@ -0,0 +1,15 @@
+package ast
+
+type Node interface {
+	TokenLiteral() string
+}
+
+type Statement interface {
+	Node
+	statementNode()
+}
+
+type Expression interface {
+	Node
+	expressionNode()
+}