diff --git a/example/ex.hyc b/example/ex.hyc
index 11f9ee5..80ba9bb 100644
--- a/example/ex.hyc
+++ b/example/ex.hyc
@@ -1,2 +1,2 @@
-fun add a b = a + b;
-let foo = add (1, 2);
\ No newline at end of file
+fun foo a b = a + b;
+let res = foo(34, 35);
\ No newline at end of file
diff --git a/src/front/parse.rs b/src/front/parse.rs
index 0c74b5d..7330752 100644
--- a/src/front/parse.rs
+++ b/src/front/parse.rs
@@ -1,10 +1,101 @@
 use chumsky::prelude::*;
 
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum Token {
+    // Types
+    Int(i64), Float(String),
+    Boolean(bool), String(String),
+    Ident(String),
+
+    // Symbols
+    Operator(String),
+    Delimiter(char),
+    Semicolon,
+    Assign, Colon,
+    Comma,
+
+    // Keywords
+    Let, Fun,
+}
+
+pub type Span = std::ops::Range<usize>;
+pub fn lexer() -> impl Parser<char, Vec<(Token, Span)>, Error = Simple<char>> {
+    let int = text::int(10)
+        .map(|s: String| Token::Int(s.parse().unwrap()));
+
+    let float = text::int(10)
+        .then_ignore(just('.'))
+        .chain::<char, _, _>(text::digits(10))
+        .collect::<String>()
+        .map(|s: String| Token::Float(s));
+
+    let string = just('"')
+        .ignore_then(filter(|c| *c != '\\' && *c != '"').repeated())
+        .then_ignore(just('"'))
+        .collect::<String>()
+        .map(|s: String| Token::String(s));
+
+    let operator = choice((
+        just("+"),
+        just("-"),
+        just("*"),
+        just("/"),
+        just("%"),
+
+        just("!"),
+        just("=="),
+        just("!="),
+        just("<"),
+        just(">"),
+        just("<="),
+        just(">="),
+    )).map(|c| Token::Operator(c.to_string()));
+
+    let delimiter = choice((
+        just('('),
+        just(')'),
+    )).map(|c| Token::Delimiter(c));
+
+    let symbol = choice((
+        just(';').to(Token::Semicolon),
+        just('=').to(Token::Assign),
+        just(':').to(Token::Colon),
+        just(',').to(Token::Comma),
+    ));
+
+    let keyword = text::ident().map(|s: String| match s.as_str() {
+        "true" => Token::Boolean(true),
+        "false" => Token::Boolean(false),
+
+        "let" => Token::Let,
+        "fun" => Token::Fun,
+        _ => Token::Ident(s),
+    });
+
+    let token = int
+        .or(float)
+        .or(string)
+        .or(operator)
+        .or(delimiter)
+        .or(symbol)
+        .or(keyword)
+        .recover_with(skip_then_retry_until([]));
+
+    let comment = just("//").then(take_until(just('\n'))).padded();
+
+    token
+        .padded_by(comment.repeated())
+        .map_with_span(|token, span| (token, span))
+        .padded()
+        .repeated()
+}
+
 #[derive(Clone, Debug)]
 pub enum Expr {
-    Int(i64),
-    Float(f64),
+    Int(i64), Float(f64),
+    Boolean(bool), String(String),
     Ident(String),
+
     Unary { op: String, expr: Box<Self> },
     Binary { op: String, left: Box<Self>, right: Box<Self> },
 
@@ -18,45 +109,67 @@ pub enum Expr {
         body: Box<Self>,
     },
     Call {
-        name: String,
+        name: Box<Self>,
         args: Vec<Self>,
     },
 }
 
-fn expr_parser() -> impl Parser<char, Expr, Error = Simple<char>> {
-    let ident = text::ident().padded();
+fn expr_parser() -> impl Parser<Token, Expr, Error = Simple<Token>> + Clone {
+    let ident = filter_map(|span, token| match token {
+        Token::Ident(s) => Ok(s.clone()),
+        _ => Err(Simple::expected_input_found(span, Vec::new(), Some(token))),
+    }).labelled("identifier");
 
     let expr = recursive(|expr| {
-        let int = text::int(10)
-            .map(|s: String| Expr::Int(s.parse().unwrap()));
-        
-        let float = text::int(10)
-            .then_ignore(just('.'))
-            .chain::<char, _, _>(text::digits(10))
-            .collect::<String>()
-            .map(|s: String| Expr::Float(s.parse().unwrap()));
+        let literal = filter_map(|span, token| match token {
+            Token::Int(i) => Ok(Expr::Int(i)),
+            Token::Float(f) => Ok(Expr::Float(f.parse().unwrap())),
+            Token::Boolean(b) => Ok(Expr::Boolean(b)),
+            Token::String(s) => Ok(Expr::String(s)),
+            _ => Err(Simple::expected_input_found(span, Vec::new(), Some(token))),
+        }).labelled("literal");
 
-        let call = ident
-            .then(expr.clone()
-                .separated_by(just(','))
-                .allow_trailing()
-                .delimited_by(just('('), just(')')))
-            .map(|(name, args)| Expr::Call { name, args });
+        let items = expr.clone()
+            .chain(just(Token::Comma)
+                .ignore_then(expr.clone()).repeated())
+            .then_ignore(just(Token::Comma).or_not())
+            .or_not()
+            .map(|item| item.unwrap_or_else(Vec::new));
 
-        let atom = int
-            .or(float)
-            .or(call)
+        let atom = literal
             .or(ident.map(Expr::Ident))
-            .or(expr.delimited_by(just('('), just(')')))
+            .or(
+                expr.clone()
+                .delimited_by(just(Token::Delimiter('(')), just(Token::Delimiter(')'))))
             .labelled("atom");
+
+        let call = atom
+            .then(
+                items
+                    .delimited_by(
+                        just(Token::Delimiter('(')),
+                        just(Token::Delimiter(')')))
+                    .repeated()
+            )
+            .foldl(|f, args| {
+                Expr::Call {
+                    name: Box::new(f),
+                    args,
+                }
+            });
         
-        let unary =  choice((just('-'), just('!')))
+        let unary =  choice((
+                just(Token::Operator("-".to_string())).to("-"),
+                just(Token::Operator("!".to_string())).to("!")))
             .repeated()
-            .then(atom)
+            .then(call)
             .foldr(|op, rhs| Expr::Unary { op: op.to_string(), expr: Box::new(rhs) }).labelled("unary");
         
         let factor = unary.clone()
-            .then(choice((just('*'), just('/')))
+            .then(
+                choice((
+                    just(Token::Operator("*".to_string())).to("*"),
+                    just(Token::Operator("/".to_string())).to("/")))
                 .then(unary)
                 .repeated())
             .foldl(|lhs, (op, rhs)| Expr::Binary {
@@ -66,7 +179,10 @@ fn expr_parser() -> impl Parser<char, Expr, Error = Simple<char>> {
             }).labelled("factor");
         
         let term = factor.clone()
-            .then(choice((just('+'), just('-')))
+            .then(
+                choice((
+                    just(Token::Operator("+".to_string())).to("+"),
+                    just(Token::Operator("-".to_string())).to("-")))
                 .then(factor)
                 .repeated())
             .foldl(|lhs, (op, rhs)| Expr::Binary {
@@ -75,26 +191,26 @@ fn expr_parser() -> impl Parser<char, Expr, Error = Simple<char>> {
                 right: Box::new(rhs)
             }).labelled("term");
         
-        term.padded()
+        term
     }).labelled("expression");
 
     let declare = recursive(|decl| {
-        let declare_var = text::keyword("let")
+        let declare_var = just(Token::Let)
             .ignore_then(ident)
-            .then_ignore(just('='))
+            .then_ignore(just(Token::Assign))
             .then(expr.clone())
-            .then_ignore(just(';'))
+            .then_ignore(just(Token::Semicolon))
             .map(|(name, rhs)| Expr::Let {
                 name,
                 value: Box::new(rhs),
             });
 
-        let declare_fun = text::keyword("fun")
+        let declare_fun = just(Token::Fun)
             .ignore_then(ident)
             .then(ident.repeated())
-            .then_ignore(just('='))
+            .then_ignore(just(Token::Assign))
             .then(expr.clone())
-            .then_ignore(just(';'))
+            .then_ignore(just(Token::Semicolon))
             .map(|((name, args), body)| Expr::Fun {
                 name,
                 args,
@@ -104,13 +220,12 @@ fn expr_parser() -> impl Parser<char, Expr, Error = Simple<char>> {
         declare_var
             .or(declare_fun)
             .or(expr)
-            .padded()
     });
 
     declare
 }
 
-pub fn parser() -> impl Parser<char, Vec<Expr>, Error = Simple<char>> {
+pub fn parser() -> impl Parser<Token, Vec<Expr>, Error = Simple<Token>> + Clone {
     expr_parser()
         .repeated()
         .then_ignore(end())
diff --git a/src/main.rs b/src/main.rs
index 40622a5..b714f95 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,6 @@
 use std::fs;
 
-use chumsky::Parser;
+use chumsky::{Parser, Stream};
 use clap::Parser as ArgParser;
 
 /// Arguments handler.
@@ -10,15 +10,21 @@ use args::{Args, Options};
 /// Front-end of the language.
 /// Contains lexer, parser and token types.
 pub mod front;
-use front::parse::parser;
+use front::parse::{lexer, parser};
 
 fn main() {
     let args = Args::parse();
     match args.options {
         Options::Compile { input: src, ast: _print_ast } => {
             let src = fs::read_to_string(src).expect("Failed to read file");
-            let tokens = parser().parse_recovery(src.as_str());
-            println!("{:?}", tokens);
+            let (tokens, lex_error) = lexer().parse_recovery(src.as_str());
+            let len = src.chars().count();
+            let (ast, parse_error) = parser().parse_recovery(Stream::from_iter(len..len + 1, tokens.clone().unwrap().into_iter()));
+            if parse_error.is_empty() {
+                println!("{:#?}", ast);
+            } else {
+                println!("{:?}", parse_error);
+            }
         },
     }
 }
\ No newline at end of file