diff --git a/src/parser/ast.rs b/src/parser/ast.rs
index e69de29..b17caf1 100644
--- a/src/parser/ast.rs
+++ b/src/parser/ast.rs
@@ -0,0 +1,180 @@
+#[derive(Debug, Clone)]
+pub struct Span {
+    pub start: usize,
+    pub end: usize,
+}
+
+#[derive(Debug, Clone)]
+pub struct Program {
+    pub statements: Vec<TopLevel>,
+}
+
+#[derive(Debug, Clone)]
+pub enum TopLevel {
+    Function(Function),
+    Struct(Struct),
+    Class(Class),
+    Import(Import),
+}
+
+#[derive(Debug, Clone)]
+pub struct Function {
+    pub name: String,
+    pub params: Vec<Param>,
+    pub return_type: Option<TypeExpr>,
+    pub body: Vec<Statement>,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct Param {
+    pub name: String,
+    pub type_expr: TypeExpr,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct Struct {
+    pub name: String,
+    pub fields: Vec<StructField>,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct StructField {
+    pub name: String,
+    pub type_expr: TypeExpr,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct Class {
+    pub name: String,
+    pub fields: Vec<StructField>,
+    pub methods: Vec<Function>,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct Import {
+    pub path: String,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub enum Statement {
+    Let(LetStatement),
+    Return(ReturnStatement),
+    Expression(Expression),
+    If(IfStatement),
+    For(ForStatement),
+}
+
+#[derive(Debug, Clone)]
+pub struct LetStatement {
+    pub name: String,
+    pub type_expr: Option<TypeExpr>,
+    pub value: Expression,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct ReturnStatement {
+    pub value: Option<Expression>,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct IfStatement {
+    pub condition: Expression,
+    pub body: Vec<Statement>,
+    pub else_body: Option<Vec<Statement>>,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct ForStatement {
+    pub var: String,
+    pub iterator: Expression,
+    pub body: Vec<Statement>,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub enum Expression {
+    Identifier(String, Span),
+    Integer(i64, Span),
+    Float(f64, Span),
+    StringLit(String, Span),
+    Bool(bool, Span),
+    BinaryOp(Box<BinaryOp>),
+    UnaryOp(Box<UnaryOp>),
+    Call(Box<CallExpr>),
+    FieldAccess(Box<FieldAccess>),
+    StructInit(Box<StructInit>),
+}
+
+#[derive(Debug, Clone)]
+pub struct BinaryOp {
+    pub left: Expression,
+    pub op: BinOperator,
+    pub right: Expression,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub enum BinOperator {
+    Add,
+    Sub,
+    Mul,
+    Div,
+    Eq,
+    NotEq,
+    Lt,
+    Gt,
+    LtEq,
+    GtEq,
+    And,
+    Or,
+}
+
+#[derive(Debug, Clone)]
+pub struct UnaryOp {
+    pub op: UnaryOperator,
+    pub expr: Expression,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub enum UnaryOperator {
+    Neg,
+    Not,
+}
+
+#[derive(Debug, Clone)]
+pub struct CallExpr {
+    pub callee: Expression,
+    pub args: Vec<Expression>,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct FieldAccess {
+    pub object: Expression,
+    pub field: String,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub struct StructInit {
+    pub name: String,
+    pub fields: Vec<(String, Expression)>,
+    pub span: Span,
+}
+
+#[derive(Debug, Clone)]
+pub enum TypeExpr {
+    Named(String),
+    Array(Box<TypeExpr>),
+    Optional(Box<TypeExpr>),
+}