diff --git a/example.yapp b/example.yapp
index 30e5ac3..1893fd8 100644
--- a/example.yapp
+++ b/example.yapp
@@ -1,11 +1,12 @@
 
 
 fn b() {
-    a();
+    a()
 }
 
 fn a() {
-
+    let abc = 123;
+    abc
 }
 
 
diff --git a/src/ast.rs b/src/ast.rs
new file mode 100644
index 0000000..d0295b8
--- /dev/null
+++ b/src/ast.rs
@@ -0,0 +1,101 @@
+use crate::pos::Pos;
+
+#[derive(Clone, PartialEq, Debug)]
+pub struct Stmt {
+    pub kind: StmtKind,
+    pub pos: Pos,
+}
+
+impl Stmt {
+    pub fn new(kind: StmtKind, pos: Pos) -> Self {
+        Self { kind, pos }
+    }
+}
+
+#[derive(Clone, PartialEq, Debug)]
+pub enum StmtKind {
+    Error,
+    Let {
+        subject: Box<Param>,
+        value: Box<Expr>,
+    },
+    Fn {
+        subject: Box<Expr>,
+        params: Vec<Param>,
+        return_typ: Option<Box<Typ>>,
+        body: Box<Expr>,
+    },
+    Return {
+        expr: Option<Box<Expr>>,
+    },
+    Break {
+        expr: Option<Box<Expr>>,
+    },
+    Assign {
+        subject: Box<Expr>,
+        value: Box<Expr>,
+    },
+    Expr(Box<Expr>),
+}
+
+#[derive(Clone, PartialEq, Debug)]
+pub struct Expr {
+    pub kind: ExprKind,
+    pub pos: Pos,
+}
+
+impl Expr {
+    pub fn new(kind: ExprKind, pos: Pos) -> Self {
+        Self { kind, pos }
+    }
+}
+
+#[derive(Clone, PartialEq, Debug)]
+pub enum ExprKind {
+    Error,
+    Ident(u64),
+    Int(i64),
+    Str(String),
+    Group(Box<Expr>),
+    Block {
+        stmts: Vec<Stmt>,
+        expr: Option<Box<Expr>>,
+    },
+    Call {
+        subject: Box<Expr>,
+        args: Vec<Expr>,
+    },
+    If {
+        cond: Box<Expr>,
+        truthy: Box<Expr>,
+        falsy: Option<Box<Expr>>,
+    },
+    Loop {
+        body: Box<Expr>,
+    },
+}
+
+#[derive(Clone, PartialEq, Debug)]
+pub struct Typ {
+    pub kind: TypKind,
+    pub pos: Pos,
+}
+
+impl Typ {
+    pub fn new(kind: TypKind, pos: Pos) -> Self {
+        Self { kind, pos }
+    }
+}
+
+#[derive(Clone, PartialEq, Debug)]
+pub enum TypKind {
+    Error,
+    Ident(u64),
+}
+
+#[derive(Clone, PartialEq, Debug)]
+pub struct Param {
+    pub subject: Box<Expr>,
+    pub typ: Option<Box<Typ>>,
+    pub pos: Pos,
+}
diff --git a/src/lexer.rs b/src/lexer.rs
index e78dcae..b88a17f 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -1,7 +1,6 @@
 use crate::{
     pos::{Error, ErrorAcc, Pos},
     token::{Token, TokenKind, TokenValue},
-    util::hash,
 };
 use std::{collections::HashMap, rc::Rc, str::Chars, sync::Mutex};
 
@@ -72,9 +71,13 @@ impl<'a> Lexer<'a> {
                             if let Some(kind) = self.keywords.get(&value) {
                                 return self.token(kind.clone(), pos);
                             }
-                            let id = hash(&value);
+                            let id = self.symbols.len() as u64;
                             self.symbols.insert(id, value);
-                            break self.token_with_value(TokenKind::Id, TokenValue::Id(id), pos);
+                            break self.token_with_value(
+                                TokenKind::Ident,
+                                TokenValue::Ident(id),
+                                pos,
+                            );
                         }
                     }
                 }
@@ -242,7 +245,7 @@ impl<'a> Lexer<'a> {
         });
     }
 
-    fn pos(&self) -> Pos {
+    pub fn pos(&self) -> Pos {
         Pos {
             index: self.index,
             line: self.line,
diff --git a/src/main.rs b/src/main.rs
index 5ce7e19..68e16b8 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,13 +1,39 @@
 #![allow(dead_code)]
 
+use std::{rc::Rc, sync::Mutex};
+
+use parser::Parser;
+use pos::{ErrorAcc, Pos};
+
+mod ast;
 mod lexer;
-mod parsed;
 mod parser;
 mod pos;
-mod sym;
 mod token;
-mod util;
 
 fn main() {
-    println!("Hello, world!");
+    let args = std::env::args().collect::<Vec<_>>();
+    let filename = args[1].clone();
+    let text = std::fs::read_to_string(filename).unwrap();
+
+    let error_acc = Rc::new(Mutex::new(ErrorAcc::new()));
+
+    let mut parser = Parser::new(&text, error_acc.clone());
+
+    let ast = parser.parse();
+
+    println!("{ast:#?}");
+
+    let error_acc = error_acc.lock().unwrap();
+    if !error_acc.ok() {
+        println!("Compilation failed");
+        for error in error_acc.iter() {
+            match error.pos {
+                Some(Pos { line, col, .. }) => {
+                    println!("{:?} at {line}:{col}: {}", error.kind, error.msg)
+                }
+                None => println!("{:?}: {}", error.kind, error.msg),
+            }
+        }
+    }
 }
diff --git a/src/parsed.rs b/src/parsed.rs
deleted file mode 100644
index 6fca65e..0000000
--- a/src/parsed.rs
+++ /dev/null
@@ -1,57 +0,0 @@
-use crate::pos::Pos;
-
-#[derive(Clone, PartialEq, Debug)]
-pub struct Node {
-    pub kind: NodeKind,
-    pub pos: Pos,
-}
-
-impl Node {
-    pub fn new(kind: NodeKind, pos: Pos) -> Self {
-        Self { kind, pos }
-    }
-}
-
-#[derive(Clone, PartialEq, Debug)]
-pub enum NodeKind {
-    Error,
-    Id(u64),
-    Int(i64),
-    Str(String),
-    Group(Box<Node>),
-    Block(Vec<Node>),
-    Call {
-        subject: Box<Node>,
-        args: Vec<Node>,
-    },
-    If {
-        cond: Box<Node>,
-        truthy: Box<Node>,
-        falsy: Option<Box<Node>>,
-    },
-    Loop {
-        body: Box<Node>,
-    },
-    Break,
-    Assign {
-        subject: Box<Node>,
-        value: Box<Node>,
-    },
-    Let {
-        subject: Box<Node>,
-        value: Box<Node>,
-    },
-    Fn {
-        subject: Box<Node>,
-        params: Vec<Node>,
-        return_typ: Box<Node>,
-        body: Box<Node>,
-    },
-    Return {
-        value: Option<Box<Node>>,
-    },
-    Param {
-        subject: Box<Node>,
-        typ: Option<Box<Node>>,
-    },
-}
diff --git a/src/parser.rs b/src/parser.rs
index 053d5a9..83b89c3 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1,10 +1,10 @@
 use std::{collections::HashMap, rc::Rc, sync::Mutex};
 
 use crate::{
+    ast::{Expr, ExprKind as EK, Param, Stmt, StmtKind as SK, Typ, TypKind},
     lexer::Lexer,
-    parsed::{Node, NodeKind},
     pos::{Error, ErrorAcc, Pos},
-    token::{Token, TokenKind, TokenValue},
+    token::{Token, TokenKind as TK, TokenValue},
 };
 
 pub struct Parser<'a> {
@@ -24,7 +24,7 @@ impl<'a> Parser<'a> {
         }
     }
 
-    pub fn parse(&mut self) -> Vec<Node> {
+    pub fn parse(&mut self) -> Vec<Stmt> {
         self.parse_file()
     }
 
@@ -32,7 +32,7 @@ impl<'a> Parser<'a> {
         self.lexer.symbols()
     }
 
-    fn parse_file(&mut self) -> Vec<Node> {
+    fn parse_file(&mut self) -> Vec<Stmt> {
         let mut stmts = Vec::new();
         loop {
             match self.current {
@@ -42,73 +42,66 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn parse_stmt(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_stmt(&mut self) -> Stmt {
+        use TK::*;
+        let pos = self.pos();
         match self.curr_kind() {
-            Some(TokenKind::LBrace) => self.parse_block(),
-            Some(TokenKind::If) => self.parse_if(),
-            Some(TokenKind::Loop) => self.parse_loop(),
-            Some(TokenKind::Fn) => self.parse_fn(),
-            _ => {
-                let stmt = match self.curr_kind() {
-                    Some(TokenKind::Let) => self.parse_let(),
-                    Some(TokenKind::Break) => {
-                        self.step();
-                        self.node(NodeKind::Break, pos.clone())
-                    }
-                    Some(TokenKind::Return) => {
-                        self.step();
-                        let value = match self.curr_kind() {
-                            Some(TokenKind::Semicolon) => None,
-                            _ => Some(Box::new(self.parse_expr())),
-                        };
-                        self.node(NodeKind::Return { value }, pos.clone())
-                    }
-                    _ => self.parse_assign(),
+            Some(Fn) => self.parse_fn(),
+            Some(kind @ (LBrace | If | Loop)) => Stmt::new(
+                SK::Expr(Box::new(match kind {
+                    LBrace => self.parse_block(),
+                    If => self.parse_if(),
+                    Loop => self.parse_loop(),
+                    _ => unreachable!(),
+                })),
+                pos,
+            ),
+            Some(kind) => {
+                let stmt = match kind {
+                    Let => self.parse_let(),
+                    Return => self.parse_return(),
+                    Break => self.parse_break(),
+                    _ => match self.parse_assign() {
+                        ParsedAssign::Assign(stmt) => stmt,
+                        ParsedAssign::Expr(expr, pos) => Stmt::new(SK::Expr(Box::new(expr)), pos),
+                    },
                 };
-                match self.curr_kind() {
-                    Some(TokenKind::Semicolon) => {
-                        self.step();
-                        stmt
-                    }
-                    _ => {
-                        self.error("expected ';'", pos.clone());
-                        self.error_node(pos)
-                    }
-                }
+                self.eat_semicolon();
+                stmt
             }
+            _ => unreachable!(),
         }
     }
 
-    fn parse_fn(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_fn(&mut self) -> Stmt {
+        let pos = self.pos();
         self.step();
-        if !self.curr_is(TokenKind::Id) {
+        if !self.curr_is(TK::Ident) {
             self.error("expected id", pos.clone());
-            return self.error_node(pos);
+            return self.error_stmt(pos);
         }
-        let subject = Box::new(self.parse_id());
-        if !self.curr_is(TokenKind::LParen) {
+        let subject = Box::new(self.parse_ident_expr());
+        if !self.curr_is(TK::LParen) {
             self.error("expected '('", pos.clone());
-            return self.error_node(pos);
+            return self.error_stmt(pos);
         }
         let params = match self.parse_fn_params() {
             Ok(params) => params,
-            Err(expr) => return expr,
+            Err(pos) => return self.error_stmt(pos),
         };
-        if !self.curr_is(TokenKind::MinusLt) {
-            self.error("expected '->'", pos.clone());
-            return self.error_node(pos);
-        }
-        self.step();
-        let return_typ = Box::new(self.parse_typ());
-        if !self.curr_is(TokenKind::LBrace) {
+        let return_typ = if self.curr_is(TK::MinusLt) {
+            self.step();
+            Some(Box::new(self.parse_typ()))
+        } else {
+            None
+        };
+        if !self.curr_is(TK::LBrace) {
             self.error("expected '{'", pos.clone());
-            return self.error_node(pos);
+            return self.error_stmt(pos);
         }
         let body = Box::new(self.parse_block());
-        self.node(
-            NodeKind::Fn {
+        Stmt::new(
+            SK::Fn {
                 subject,
                 params,
                 return_typ,
@@ -118,49 +111,49 @@ impl<'a> Parser<'a> {
         )
     }
 
-    fn parse_fn_params(&mut self) -> Result<Vec<Node>, Node> {
-        let pos = self.pos().unwrap();
+    fn parse_fn_params(&mut self) -> Result<Vec<Param>, Pos> {
+        let pos = self.pos();
         self.step();
         let mut params = Vec::new();
-        if !self.curr_is(TokenKind::RParen) {
-            if !self.curr_is(TokenKind::Id) {
+        if !self.curr_is(TK::RParen) {
+            if !self.curr_is(TK::Ident) {
                 self.error("expected id", pos.clone());
-                return Err(self.error_node(pos));
+                return Err(pos);
             }
             params.push(self.parse_param());
-            while let Some(TokenKind::Comma) = self.curr_kind() {
+            while let Some(TK::Comma) = self.curr_kind() {
                 self.step();
-                if self.curr_is(TokenKind::RParen) {
+                if self.curr_is(TK::RParen) {
                     self.error("expected ')'", pos.clone());
                     break;
                 }
                 params.push(self.parse_param());
             }
         }
-        if !self.curr_is(TokenKind::RParen) {
+        if !self.curr_is(TK::RParen) {
             self.error("expected ')'", pos.clone());
-            return Err(self.error_node(pos));
+            return Err(pos);
         }
         self.step();
         Ok(params)
     }
 
-    fn parse_let(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_let(&mut self) -> Stmt {
+        let pos = self.pos();
         self.step();
-        if !self.curr_is(TokenKind::Id) {
+        if !self.curr_is(TK::Ident) {
             self.error("expected id", pos.clone());
-            return self.error_node(pos);
+            return self.error_stmt(pos);
         }
         let subject = self.parse_param();
-        if !self.curr_is(TokenKind::Equal) {
+        if !self.curr_is(TK::Equal) {
             self.error("expected '='", pos.clone());
-            return self.error_node(pos);
+            return self.error_stmt(pos);
         }
         self.step();
         let value = self.parse_expr();
-        self.node(
-            NodeKind::Let {
+        Stmt::new(
+            SK::Let {
                 subject: Box::new(subject),
                 value: Box::new(value),
             },
@@ -168,68 +161,64 @@ impl<'a> Parser<'a> {
         )
     }
 
-    fn parse_param(&mut self) -> Node {
-        let pos = self.pos().unwrap();
-        let subject = Box::new(self.parse_id());
-        let typ = if let Some(TokenKind::Colon) = self.curr_kind() {
-            self.step();
-            Some(Box::new(self.parse_typ()))
-        } else {
-            None
+    fn parse_return(&mut self) -> Stmt {
+        let pos = self.pos();
+        self.step();
+        let expr = match self.curr_kind() {
+            Some(TK::Semicolon) => None,
+            _ => Some(Box::new(self.parse_expr())),
         };
-        self.node(NodeKind::Param { subject, typ }, pos)
+        Stmt::new(SK::Return { expr }, pos.clone())
     }
 
-    fn parse_typ(&mut self) -> Node {
-        let pos = self.pos().unwrap();
-        match self.curr_kind() {
-            Some(TokenKind::Id) => self.parse_id(),
-            _ => {
-                self.error("expected type", pos.clone());
-                self.step();
-                self.error_node(pos)
-            }
-        }
+    fn parse_break(&mut self) -> Stmt {
+        let pos = self.pos();
+        self.step();
+        let expr = match self.curr_kind() {
+            Some(TK::Semicolon) => None,
+            _ => Some(Box::new(self.parse_expr())),
+        };
+        Stmt::new(SK::Break { expr }, pos.clone())
     }
 
-    fn parse_assign(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_assign(&mut self) -> ParsedAssign {
+        let pos = self.pos();
         let subject = self.parse_expr();
         match self.curr_kind() {
-            Some(TokenKind::Equal) => {
+            Some(TK::Equal) => {
                 self.step();
                 let value = self.parse_expr();
-                self.node(
-                    NodeKind::Assign {
+                ParsedAssign::Assign(Stmt::new(
+                    SK::Assign {
                         subject: Box::new(subject),
                         value: Box::new(value),
                     },
                     pos,
-                )
+                ))
             }
-            _ => subject,
+            _ => ParsedAssign::Expr(subject, pos),
         }
     }
 
-    fn parse_expr(&mut self) -> Node {
+    fn parse_expr(&mut self) -> Expr {
         self.parse_call()
     }
 
-    fn parse_call(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_call(&mut self) -> Expr {
+        let pos = self.pos();
         let mut subject = self.parse_value();
         loop {
             match self.curr_kind() {
-                Some(TokenKind::LParen) => {
+                Some(TK::LParen) => {
                     self.step();
                     let mut args = Vec::new();
                     match self.curr_kind() {
-                        None | Some(TokenKind::RParen) => {}
+                        None | Some(TK::RParen) => {}
                         Some(_) => {
                             args.push(self.parse_expr());
-                            while let Some(TokenKind::Comma) = self.curr_kind() {
+                            while let Some(TK::Comma) = self.curr_kind() {
                                 self.step();
-                                if let Some(TokenKind::RParen) = self.curr_kind() {
+                                if let Some(TK::RParen) = self.curr_kind() {
                                     break;
                                 }
                                 args.push(self.parse_expr());
@@ -237,15 +226,15 @@ impl<'a> Parser<'a> {
                         }
                     }
                     match self.curr_kind() {
-                        Some(TokenKind::RParen) => {}
+                        Some(TK::RParen) => {}
                         _ => {
                             self.error("expected ')'", pos.clone());
-                            return self.error_node(pos);
+                            return self.error_expr(pos);
                         }
                     }
                     self.step();
-                    subject = self.node(
-                        NodeKind::Call {
+                    subject = Expr::new(
+                        EK::Call {
                             subject: Box::new(subject),
                             args,
                         },
@@ -257,42 +246,42 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn parse_value(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_value(&mut self) -> Expr {
+        let pos = self.pos();
         match self.curr_kind() {
-            Some(TokenKind::Id) => self.parse_id(),
-            Some(TokenKind::Int) => self.parse_int(),
-            Some(TokenKind::Str) => self.parse_string(),
-            Some(TokenKind::LParen) => self.parse_group(),
-            Some(TokenKind::LBrace) => self.parse_block(),
-            Some(TokenKind::If) => self.parse_if(),
-            Some(TokenKind::Loop) => self.parse_loop(),
+            Some(TK::Ident) => self.parse_ident_expr(),
+            Some(TK::Int) => self.parse_int(),
+            Some(TK::Str) => self.parse_string(),
+            Some(TK::LParen) => self.parse_group(),
+            Some(TK::LBrace) => self.parse_block(),
+            Some(TK::If) => self.parse_if(),
+            Some(TK::Loop) => self.parse_loop(),
             _ => {
                 self.error("expected value", pos.clone());
                 self.step();
-                self.error_node(pos)
+                self.error_expr(pos)
             }
         }
     }
 
-    fn parse_id(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_ident_expr(&mut self) -> Expr {
+        let pos = self.pos();
         let Some(Token {
-            kind: TokenKind::Id,
-            value: TokenValue::Id(value),
+            kind: TK::Ident,
+            value: TokenValue::Ident(value),
             ..
         }) = self.current
         else {
             unreachable!()
         };
         self.step();
-        self.node(NodeKind::Id(value), pos)
+        Expr::new(EK::Ident(value), pos)
     }
 
-    fn parse_int(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_int(&mut self) -> Expr {
+        let pos = self.pos();
         let Some(Token {
-            kind: TokenKind::Int,
+            kind: TK::Int,
             value: TokenValue::Int(value),
             ..
         }) = self.current
@@ -300,13 +289,13 @@ impl<'a> Parser<'a> {
             unreachable!()
         };
         self.step();
-        self.node(NodeKind::Int(value), pos)
+        Expr::new(EK::Int(value), pos)
     }
 
-    fn parse_string(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_string(&mut self) -> Expr {
+        let pos = self.pos();
         let Some(Token {
-            kind: TokenKind::Str,
+            kind: TK::Str,
             value: TokenValue::Str(value),
             ..
         }) = self.current.clone()
@@ -314,62 +303,121 @@ impl<'a> Parser<'a> {
             unreachable!()
         };
         self.step();
-        self.node(NodeKind::Str(value.clone()), pos)
+        Expr::new(EK::Str(value.clone()), pos)
     }
 
-    fn parse_group(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_group(&mut self) -> Expr {
+        let pos = self.pos();
         self.step();
         let expr = Box::new(self.parse_expr());
-        if !self.curr_is(TokenKind::RParen) {
+        if !self.curr_is(TK::RParen) {
             self.error("expected ')'", pos.clone());
-            return self.error_node(pos);
+            return self.error_expr(pos);
         }
         self.step();
-        self.node(NodeKind::Group(expr), pos)
+        Expr::new(EK::Group(expr), pos)
     }
 
-    fn parse_block(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_block(&mut self) -> Expr {
+        use TK::*;
+        let pos = self.pos();
         self.step();
         let mut stmts = Vec::new();
         loop {
             match self.curr_kind() {
                 None => {
-                    self.error("expected ')'", pos.clone());
-                    break self.error_node(pos);
+                    self.error("expected '}'", pos.clone());
+                    break self.error_expr(pos);
                 }
-                Some(TokenKind::RBrace) => {
+                Some(RBrace) => {
                     self.step();
-                    break self.node(NodeKind::Block(stmts), pos);
+                    break Expr::new(EK::Block { stmts, expr: None }, pos);
                 }
-                _ => stmts.push(self.parse_stmt()),
+                Some(Fn) => stmts.push(self.parse_fn()),
+                Some(kind @ (Let | Return | Break)) => {
+                    let stmt = match kind {
+                        Let => self.parse_let(),
+                        Return => self.parse_return(),
+                        Break => self.parse_break(),
+                        _ => unreachable!(),
+                    };
+                    self.eat_semicolon();
+                    stmts.push(stmt);
+                }
+                Some(kind @ (LBrace | If | Loop)) => {
+                    let expr = match kind {
+                        LBrace => self.parse_block(),
+                        If => self.parse_if(),
+                        Loop => self.parse_loop(),
+                        _ => unreachable!(),
+                    };
+                    match self.curr_kind() {
+                        Some(TK::Semicolon) => {
+                            self.step();
+                            stmts.push(Stmt::new(SK::Expr(Box::new(expr)), pos.clone()))
+                        }
+                        Some(TK::RBrace) => {
+                            self.step();
+                            break Expr::new(
+                                EK::Block {
+                                    stmts,
+                                    expr: Some(Box::new(expr)),
+                                },
+                                pos,
+                            );
+                        }
+                        _ => {}
+                    }
+                }
+                Some(_) => match self.parse_assign() {
+                    ParsedAssign::Assign(stmt) => {
+                        self.eat_semicolon();
+                        stmts.push(stmt);
+                    }
+                    ParsedAssign::Expr(expr, pos) => match self.curr_kind() {
+                        Some(TK::Semicolon) => {
+                            self.step();
+                            stmts.push(Stmt::new(SK::Expr(Box::new(expr)), pos))
+                        }
+                        Some(TK::RBrace) => {
+                            self.step();
+                            break Expr::new(
+                                EK::Block {
+                                    stmts,
+                                    expr: Some(Box::new(expr)),
+                                },
+                                pos,
+                            );
+                        }
+                        _ => {}
+                    },
+                },
             }
         }
     }
 
-    fn parse_if(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_if(&mut self) -> Expr {
+        let pos = self.pos();
         self.step();
         let cond = Box::new(self.parse_expr());
-        if !self.curr_is(TokenKind::LBrace) {
+        if !self.curr_is(TK::LBrace) {
             self.error("expected '}'", pos.clone());
-            return self.error_node(pos);
+            return self.error_expr(pos);
         }
         let truthy = Box::new(self.parse_block());
         let falsy = match self.curr_kind() {
-            Some(TokenKind::Else) => {
+            Some(TK::Else) => {
                 self.step();
-                if !self.curr_is(TokenKind::LBrace) {
+                if !self.curr_is(TK::LBrace) {
                     self.error("expected '}'", pos.clone());
-                    return self.error_node(pos);
+                    return self.error_expr(pos);
                 }
                 Some(Box::new(self.parse_block()))
             }
             _ => None,
         };
-        self.node(
-            NodeKind::If {
+        Expr::new(
+            EK::If {
                 cond,
                 truthy,
                 falsy,
@@ -378,15 +426,65 @@ impl<'a> Parser<'a> {
         )
     }
 
-    fn parse_loop(&mut self) -> Node {
-        let pos = self.pos().unwrap();
+    fn parse_loop(&mut self) -> Expr {
+        let pos = self.pos();
         self.step();
-        if !self.curr_is(TokenKind::LBrace) {
+        if !self.curr_is(TK::LBrace) {
             self.error("expected '}'", pos.clone());
-            return self.error_node(pos);
+            return self.error_expr(pos);
         }
         let body = Box::new(self.parse_block());
-        self.node(NodeKind::Loop { body }, pos)
+        Expr::new(EK::Loop { body }, pos)
+    }
+
+    fn parse_typ(&mut self) -> Typ {
+        let pos = self.pos();
+        match self.curr_kind() {
+            Some(TK::Ident) => self.parse_ident_typ(),
+            _ => {
+                self.error("expected type", pos.clone());
+                self.step();
+                self.error_typ(pos)
+            }
+        }
+    }
+
+    fn parse_ident_typ(&mut self) -> Typ {
+        let pos = self.pos();
+        let Some(Token {
+            kind: TK::Ident,
+            value: TokenValue::Ident(value),
+            ..
+        }) = self.current
+        else {
+            unreachable!()
+        };
+        self.step();
+        Typ::new(TypKind::Ident(value), pos)
+    }
+
+    fn parse_param(&mut self) -> Param {
+        let pos = self.pos();
+        let subject = Box::new(self.parse_ident_expr());
+        let typ = if let Some(TK::Colon) = self.curr_kind() {
+            self.step();
+            Some(Box::new(self.parse_typ()))
+        } else {
+            None
+        };
+        Param { subject, typ, pos }
+    }
+
+    fn eat_semicolon(&mut self) {
+        let pos = self.pos();
+        match self.curr_kind() {
+            Some(TK::Semicolon) => {
+                self.step();
+            }
+            _ => {
+                self.error("expected ';'", pos.clone());
+            }
+        }
     }
 
     fn error<S: Into<String>>(&mut self, msg: S, pos: Pos) {
@@ -402,26 +500,35 @@ impl<'a> Parser<'a> {
         self.current = self.lexer.next();
     }
 
-    fn node(&self, kind: NodeKind, pos: Pos) -> Node {
-        Node { kind, pos }
+    fn error_stmt(&self, pos: Pos) -> Stmt {
+        Stmt::new(SK::Error, pos)
     }
 
-    fn error_node(&self, pos: Pos) -> Node {
-        Node {
-            kind: NodeKind::Error,
-            pos,
-        }
+    fn error_expr(&self, pos: Pos) -> Expr {
+        Expr::new(EK::Error, pos)
     }
 
-    fn pos(&self) -> Option<Pos> {
-        self.current.as_ref().map(|token| token.pos.clone())
+    fn error_typ(&self, pos: Pos) -> Typ {
+        Typ::new(TypKind::Error, pos)
     }
 
-    fn curr_is(&self, kind: TokenKind) -> bool {
+    fn pos(&self) -> Pos {
+        self.current
+            .as_ref()
+            .map(|token| token.pos.clone())
+            .unwrap_or_else(|| self.lexer.pos())
+    }
+
+    fn curr_is(&self, kind: TK) -> bool {
         self.curr_kind() == Some(kind)
     }
 
-    fn curr_kind(&self) -> Option<TokenKind> {
+    fn curr_kind(&self) -> Option<TK> {
         self.current.as_ref().map(|t| t.kind.clone())
     }
 }
+
+enum ParsedAssign {
+    Assign(Stmt),
+    Expr(Expr, Pos),
+}
diff --git a/src/pos.rs b/src/pos.rs
index d4dc755..446ff39 100644
--- a/src/pos.rs
+++ b/src/pos.rs
@@ -41,4 +41,8 @@ impl ErrorAcc {
     pub fn add(&mut self, error: Error) {
         self.errors.push(error)
     }
+
+    pub fn iter(&self) -> impl Iterator<Item = &Error> {
+        self.errors.iter()
+    }
 }
diff --git a/src/token.rs b/src/token.rs
index 5f2a8ee..16030be 100644
--- a/src/token.rs
+++ b/src/token.rs
@@ -10,7 +10,7 @@ pub struct Token {
 #[derive(Clone, PartialEq, Debug)]
 pub enum TokenKind {
     Error,
-    Id,
+    Ident,
     Int,
     Str,
     If,
@@ -34,7 +34,7 @@ pub enum TokenKind {
 #[derive(Clone, PartialEq, Debug)]
 pub enum TokenValue {
     None,
-    Id(u64),
+    Ident(u64),
     Int(i64),
     Str(String),
 }