diff --git a/example.ed b/example.ed
index e80bb0e81..d863d7052 100644
--- a/example.ed
+++ b/example.ed
@@ -1,9 +1,9 @@
-fn add(a: i64, b: i64) -> i64 {
+fn add(a: i32, b: i32) -> i32 {
     return a + b;
 }
 
-fn main() {
+fn main() -> i32 {
     let x = 2 + 3;
     let y = add(x, 4);
-    return;
+    return y;
 }
diff --git a/simple.ed b/simple.ed
new file mode 100644
index 000000000..d3131726c
--- /dev/null
+++ b/simple.ed
@@ -0,0 +1,5 @@
+
+fn main(x: i64) -> i64 {
+    let x = 2 + 3;
+    return x;
+}
diff --git a/src/ast/mod.rs b/src/ast/mod.rs
index 7e1cf4815..41494b3af 100644
--- a/src/ast/mod.rs
+++ b/src/ast/mod.rs
@@ -23,7 +23,7 @@ impl OpCode {
 pub enum LiteralValue {
     String,
     Integer {
-        bits: usize,
+        bits: Option<u32>,
         signed: bool,
         value: String,
     },
diff --git a/src/codegen.rs b/src/codegen.rs
index e050038f4..b37c99b63 100644
--- a/src/codegen.rs
+++ b/src/codegen.rs
@@ -1,4 +1,8 @@
-use std::collections::HashMap;
+use std::{
+    collections::HashMap,
+    path::{Path, PathBuf},
+    todo,
+};
 
 use color_eyre::Result;
 use inkwell::{
@@ -10,21 +14,19 @@ use inkwell::{
     values::{BasicMetadataValueEnum, BasicValue, BasicValueEnum},
 };
 use itertools::{Either, Itertools};
-/*
-use statement::Statement;
 
-use crate::ast::{self, statement, Expression, Function, Identifier, OpCode, SpanValue, Term, LiteralValue};
+use crate::ast::{self, Expression, Function, LiteralValue, OpCode, Statement};
 
 #[derive(Debug, Clone)]
 pub struct ProgramData {
-    pub filename: String,
+    pub filename: PathBuf,
     pub source: String,
 }
 
 impl ProgramData {
-    pub fn new(filename: &str, source: &str) -> Self {
+    pub fn new(filename: &Path, source: &str) -> Self {
         Self {
-            filename: filename.to_string(),
+            filename: filename.to_path_buf(),
             source: source.to_string(),
         }
     }
@@ -65,9 +67,8 @@ impl<'ctx> CodeGen<'ctx> {
 
         // create the llvm functions first.
         for statement in &self.ast.statements {
-            match &statement.value {
-                Statement::Assignment(_) => unreachable!(),
-                Statement::Definition(_) => todo!(),
+            match &statement {
+                Statement::Variable { .. } => unreachable!(),
                 Statement::Return(_) => unreachable!(),
                 Statement::Function(function) => {
                     functions.push(function);
@@ -106,7 +107,7 @@ impl<'ctx> CodeGen<'ctx> {
         let args_types: Vec<BasicTypeEnum<'ctx>> = function
             .params
             .iter()
-            .map(|param| param.type_name.0.value.as_str())
+            .map(|param| param.type_name.as_str())
             .map(|t| self.get_llvm_type(t))
             .try_collect()?;
 
@@ -114,18 +115,17 @@ impl<'ctx> CodeGen<'ctx> {
             args_types.into_iter().map(|t| t.into()).collect_vec();
 
         let fn_type = match &function.return_type {
-            Some(id) => self.get_llvm_type(&id.0.value)?.fn_type(&args_types, false),
+            Some(id) => self.get_llvm_type(id)?.fn_type(&args_types, false),
             None => self.context.void_type().fn_type(&args_types, false),
         };
 
-        self.module
-            .add_function(&function.ident.0.value, fn_type, None);
+        self.module.add_function(&function.name, fn_type, None);
 
         Ok(())
     }
 
     fn compile_function(&self, function: &Function) -> Result<()> {
-        let func = self.module.get_function(&function.ident.0.value).unwrap();
+        let func = self.module.get_function(&function.name).unwrap();
         let entry_block = self.context.append_basic_block(func, "entry");
 
         self.builder.position_at_end(entry_block);
@@ -135,7 +135,7 @@ impl<'ctx> CodeGen<'ctx> {
         for (i, param) in function.params.iter().enumerate() {
             let id = param.ident.clone();
             variables.insert(
-                id.0.value.clone(),
+                id.clone(),
                 func.get_nth_param(i.try_into().unwrap())
                     .expect("parameter"),
             );
@@ -145,7 +145,7 @@ impl<'ctx> CodeGen<'ctx> {
         let mut has_return = false;
 
         for statement in &function.body {
-            if let Statement::Return(_) = statement.value {
+            if let Statement::Return(_) = statement {
                 has_return = true
             }
             self.compile_statement(&entry_block, statement, &mut variables)?;
@@ -161,24 +161,17 @@ impl<'ctx> CodeGen<'ctx> {
     fn compile_statement(
         &self,
         block: &BasicBlock,
-        statement: &SpanValue<Statement>,
+        statement: &Statement,
         variables: &mut HashMap<String, BasicValueEnum<'ctx>>,
     ) -> Result<()> {
-        match &statement.value {
+        match statement {
             // Variable assignment
-            Statement::Assignment(body) => {
+            Statement::Variable { name, value } => {
                 let result = self
-                    .compile_expression(block, &body.expr, variables)?
+                    .compile_expression(block, value, variables)?
                     .expect("should have result");
 
-                variables.insert(body.ident.0.value.clone(), result);
-            }
-            Statement::Definition(body) => {
-                let result = self
-                    .compile_expression(block, &body.expr, variables)?
-                    .expect("should have result");
-
-                variables.insert(body.ident.0.value.clone(), result);
+                variables.insert(name.clone(), result);
             }
             Statement::Return(ret) => {
                 if let Some(ret) = ret {
@@ -199,24 +192,28 @@ impl<'ctx> CodeGen<'ctx> {
     pub fn compile_expression(
         &self,
         block: &BasicBlock,
-        expr: &SpanValue<Box<Expression>>,
+        expr: &Expression,
         variables: &mut HashMap<String, BasicValueEnum<'ctx>>,
     ) -> Result<Option<BasicValueEnum<'ctx>>> {
-        Ok(match &*expr.value {
-            Expression::Literal(term) => Some(self.compile_term(&term, variables)?),
-            Expression::Call(func_id, args) => self.compile_call(block, func_id, args, variables)?,
-            Expression::BinaryOp(lhs, op, rhs) => Some(self.compile_op(block, lhs, op, rhs, variables)?),
+        Ok(match expr {
+            Expression::Variable(term) => Some(self.compile_variable(term, variables)?),
+            Expression::Literal(term) => Some(self.compile_literal(term)?),
+            Expression::Call { function, args } => {
+                self.compile_call(block, function, args, variables)?
+            }
+            Expression::BinaryOp(lhs, op, rhs) => {
+                Some(self.compile_binary_op(block, lhs, op, rhs, variables)?)
+            }
         })
     }
 
     pub fn compile_call(
         &self,
         block: &BasicBlock,
-        func_id: &Identifier,
-        args: &[SpanValue<Box<Expression>>],
+        func_name: &str,
+        args: &[Box<Expression>],
         variables: &mut HashMap<String, BasicValueEnum<'ctx>>,
     ) -> Result<Option<BasicValueEnum<'ctx>>> {
-        let func_name = &func_id.0.value;
         let function = self.module.get_function(func_name).expect("should exist");
 
         let mut value_args: Vec<BasicMetadataValueEnum> = Vec::with_capacity(args.len());
@@ -239,12 +236,12 @@ impl<'ctx> CodeGen<'ctx> {
         })
     }
 
-    pub fn compile_op(
+    pub fn compile_binary_op(
         &self,
         block: &BasicBlock,
-        lhs: &SpanValue<Box<Expression>>,
+        lhs: &Expression,
         op: &OpCode,
-        rhs: &SpanValue<Box<Expression>>,
+        rhs: &Expression,
         variables: &mut HashMap<String, BasicValueEnum<'ctx>>,
     ) -> Result<BasicValueEnum<'ctx>> {
         let lhs = self
@@ -267,21 +264,33 @@ impl<'ctx> CodeGen<'ctx> {
         Ok(result.as_basic_value_enum())
     }
 
-    pub fn compile_term(
-        &self,
-        term: &LiteralValue,
-        variables: &mut HashMap<String, BasicValueEnum<'ctx>>,
-    ) -> Result<BasicValueEnum<'ctx>> {
+    pub fn compile_literal(&self, term: &LiteralValue) -> Result<BasicValueEnum<'ctx>> {
         let value = match term {
-            Term::Identifier(ident) => *variables.get(&ident.0.value).expect("value"),
-            Term::Number(num) => self
-                .context
-                .i64_type()
-                .const_int(num.0.value.try_into()?, true)
-                .as_basic_value_enum(),
+            LiteralValue::String => todo!(),
+            LiteralValue::Integer {
+                bits,
+                signed: _,
+                value,
+            } => {
+                // todo: type resolution for bit size?
+                let bits = bits.unwrap_or(32);
+
+                self.context
+                    .custom_width_int_type(bits)
+                    .const_int(value.parse().unwrap(), false)
+                    .as_basic_value_enum()
+            }
         };
 
         Ok(value)
     }
+
+    pub fn compile_variable(
+        &self,
+        variable: &str,
+        variables: &mut HashMap<String, BasicValueEnum<'ctx>>,
+    ) -> Result<BasicValueEnum<'ctx>> {
+        let var = *variables.get(variable).expect("value");
+        Ok(var)
+    }
 }
- */
diff --git a/src/grammar.lalrpop b/src/grammar.lalrpop
index 8c9c125ce..7bd230317 100644
--- a/src/grammar.lalrpop
+++ b/src/grammar.lalrpop
@@ -1,8 +1,40 @@
 use std::str::FromStr;
-use crate::ast::*;
+use crate::{
+    ast,
+    tokens::Token,
+    lexer::LexicalError,
+};
 
 grammar;
 
+extern {
+    type Location = usize;
+    type Error = LexicalError;
+
+    enum Token {
+      "let" => Token::KeywordLet,
+      "print" => Token::KeywordPrint,
+      "identifier" => Token::Identifier(<String>),
+      "int" => Token::Integer(<String>),
+      "return" => Token::KeywordReturn,
+      "fn" => Token::KeywordFn,
+      "(" => Token::LeftParen,
+      ")" => Token::RightParen,
+      "{" => Token::LeftBracket,
+      "}" => Token::RightBracket,
+      "=" => Token::Assign,
+      ";" => Token::Semicolon,
+      ":" => Token::Colon,
+      "->" => Token::Arrow,
+      "," => Token::Coma,
+      "+" => Token::OperatorAdd,
+      "-" => Token::OperatorSub,
+      "*" => Token::OperatorMul,
+      "/" => Token::OperatorDiv,
+      "%" => Token::OperatorRem,
+    }
+}
+
 Comma<T>: Vec<T> = {
     <mut v:(<T> ",")*> <e:T?> => match e {
         None => v,
@@ -13,67 +45,11 @@ Comma<T>: Vec<T> = {
     }
 };
 
-ExprOp: OpCode = {
-    "+" => OpCode::Add,
-    "-" => OpCode::Sub,
-};
-
-FactorOp: OpCode = {
-    "*" => OpCode::Mul,
-    "/" => OpCode::Div,
-    "%" => OpCode::Rem,
+pub Program: ast::Program = {
+    Statements => ast::Program::new(<>)
 }
 
-Tier<Op,NextTier>: Box<Expression> = {
-    <t:Tier<Op,NextTier>> <o:Op> <n:NextTier> => Box::new(Expression::BinaryOp(t, o, n)),
-    NextTier
-};
-
-Expr = Tier<ExprOp, Factor>;
-Factor = Tier<FactorOp, Term>;
-
-// Terms: variables, literals, calls
-Term: Box<Expression> = {
-    <i:Identifier> => Box::new(Expression::Variable(i)),
-    <n:Num> => Box::new(Expression::Literal(n)),
-    <i:Identifier> "(" <values:Comma<Term>> ")" => Box::new(Expression::Call { function: i, args: values}),
-    "(" <Term> ")"
-};
-
-Identifier: String = {
-    <i:r"[a-zA-Z][\w]*"> => i.to_string(),
-};
-
-Num: LiteralValue = <n:r"[0-9]+"> => LiteralValue::Integer { bits: 32, signed: true, value: n.to_string()};
-
-// Function handling
-Param: Parameter = {
-    <Identifier> ":" <Identifier> => Parameter::new(<>)
-};
-
-Params = Comma<Param>;
-
-FunctionReturn: String = {
-    "->" <i:Identifier> => i.to_string(),
-}
-
-Function: Function = {
-    "fn" <i:Identifier> "(" <a:Params> ")" <r:FunctionReturn?> "{" <s:Statements> "}" => Function::new(i, a, s, r)
-}
-
-// statements not including function definitions
-BasicStatement: Statement = {
-    "let" <i:Identifier> "=" <e:Expr> ";" => Statement::Variable { name: i, value: e},
-    <i:Identifier> "=" <e:Expr> ";" => Statement::Variable { name: i, value: e},
-    "return" <e:Expr?> ";" => Statement::Return(e),
-};
-
-Statement: Statement = {
-    BasicStatement,
-    <f:Function> => Statement::Function(f),
-};
-
-Statements: Vec<Statement> = {
+Statements: Vec<ast::Statement> = {
     Statement => vec![<>],
     <mut s:Statements> <n:Statement> => {
         s.push(n);
@@ -81,6 +57,58 @@ Statements: Vec<Statement> = {
     },
 };
 
-pub Program: Program = {
-    Statements => Program::new(<>)
+Statement: ast::Statement = {
+    BasicStatement,
+    <f:Function> => ast::Statement::Function(f),
+};
+
+// statements not including function definitions
+BasicStatement: ast::Statement = {
+    "let" <i:"identifier"> "=" <e:Expr> ";" => ast::Statement::Variable { name: i, value: e},
+    <i:"identifier"> "=" <e:Expr> ";" => ast::Statement::Variable { name: i, value: e},
+    "return" <e:Expr?> ";" => ast::Statement::Return(e),
+};
+
+ExprOp: ast::OpCode = {
+    "+" => ast::OpCode::Add,
+    "-" => ast::OpCode::Sub,
+};
+
+FactorOp: ast::OpCode = {
+    "*" => ast::OpCode::Mul,
+    "/" => ast::OpCode::Div,
+    "%" => ast::OpCode::Rem,
+}
+
+Tier<Op,NextTier>: Box<ast::Expression> = {
+    <t:Tier<Op,NextTier>> <o:Op> <n:NextTier> => Box::new(ast::Expression::BinaryOp(t, o, n)),
+    NextTier
+};
+
+Expr = Tier<ExprOp, Factor>;
+Factor = Tier<FactorOp, Term>;
+
+// Terms: variables, literals, calls
+Term: Box<ast::Expression> = {
+    <i:"identifier"> => Box::new(ast::Expression::Variable(i)),
+    <n:Num> => Box::new(ast::Expression::Literal(n)),
+    <i:"identifier"> "(" <values:Comma<Term>> ")" => Box::new(ast::Expression::Call { function: i, args: values}),
+    "(" <Term> ")"
+};
+
+Num: ast::LiteralValue = <n:"int"> => ast::LiteralValue::Integer { bits: None, signed: true, value: n.to_string()};
+
+// Function handling
+Param: ast::Parameter = {
+    <"identifier"> ":" <"identifier"> => ast::Parameter::new(<>)
+};
+
+Params = Comma<Param>;
+
+FunctionReturn: String = {
+    "->" <i:"identifier"> => i.to_string(),
+}
+
+Function: ast::Function = {
+    "fn" <i:"identifier"> "(" <a:Params> ")" <r:FunctionReturn?> "{" <s:Statements> "}" => ast::Function::new(i, a, s, r)
 }
diff --git a/src/lexer.rs b/src/lexer.rs
index cbdb0ef0f..f56a76772 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -4,6 +4,7 @@ use crate::tokens::Token;
 
 pub type Spanned<Tok, Loc, Error> = Result<(Loc, Tok, Loc), Error>;
 
+#[derive(Debug, Clone, Copy)]
 pub enum LexicalError {
     InvalidToken,
 }
diff --git a/src/main.rs b/src/main.rs
index 8ceee9275..bc19dcbfd 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,11 +1,14 @@
 #![allow(clippy::too_many_arguments)]
 
 use clap::{Parser, Subcommand};
+use codegen::ProgramData;
 use color_eyre::Result;
 use inkwell::{context::Context, execution_engine::JitFunction, OptimizationLevel};
 use lalrpop_util::lalrpop_mod;
 use std::{fs, path::PathBuf, println};
 
+use crate::{ast::Program, lexer::Lexer};
+
 pub mod ast;
 pub mod check;
 pub mod codegen;
@@ -90,12 +93,12 @@ fn main() -> Result<()> {
 
     match args.command {
         Commands::Check { input } => {
-            let code = fs::read_to_string(&input)?;
-
+            let code = fs::read_to_string(input)?;
+            let lexer = Lexer::new(code.as_str());
             let parser = grammar::ProgramParser::new();
-            let ast = parser.parse(&code).unwrap();
+            let ast = parser.parse(lexer).unwrap();
 
-            let str_path = input.to_string_lossy();
+            //let str_path = input.to_string_lossy();
             //let program = ProgramData::new(&str_path, &code);
             //check_program(&program, &ast);
         }
@@ -106,21 +109,17 @@ fn main() -> Result<()> {
             optimize: _,
         } => {
             let code = fs::read_to_string(&input)?;
-
+            let lexer = Lexer::new(code.as_str());
             let parser = grammar::ProgramParser::new();
-            let ast = parser.parse(&code).unwrap();
+            let ast: Program = parser.parse(lexer).unwrap();
 
-            println!("{:#?}", ast);
-
-            /*
-            let str_path = input.to_string_lossy();
-            let program = ProgramData::new(&str_path, &code);
+            let program = ProgramData::new(&input, &code);
 
             let file_name = input.file_name().unwrap().to_string_lossy();
 
-            if !check_program(&program, &ast) {
-                return Ok(());
-            }
+            //if !check_program(&program, &ast) {
+            //    return Ok(());
+            //}
 
             let context = Context::create();
             let codegen = codegen::CodeGen::new(&context, &file_name, program, ast)?;
@@ -132,16 +131,14 @@ fn main() -> Result<()> {
             } else {
                 println!("{generated_llvm_ir}");
             }
-            */
         }
         Commands::Run { input } => {
             let code = fs::read_to_string(&input)?;
-
+            let lexer = Lexer::new(&code[..]);
             let parser = grammar::ProgramParser::new();
-            let ast = parser.parse(&code).unwrap();
-            /*
-            let str_path = input.to_string_lossy();
-            let program = ProgramData::new(&str_path, &code);
+            let ast = parser.parse(lexer).unwrap();
+
+            let program = ProgramData::new(&input, &code);
 
             let file_name = input.file_name().unwrap().to_string_lossy();
 
@@ -158,7 +155,6 @@ fn main() -> Result<()> {
                     execution_engine.get_function("main")?;
                 main.call();
             };
-            */
         }
     }
 
diff --git a/src/tokens.rs b/src/tokens.rs
index 0663293bc..ac8a7ab44 100644
--- a/src/tokens.rs
+++ b/src/tokens.rs
@@ -1,27 +1,42 @@
 use logos::Logos;
 use std::fmt;
 
-#[derive(Logos, Debug, PartialEq)]
+// todo: https://github.com/maciejhirsz/logos/issues/133#issuecomment-619444615
+#[derive(Logos, Debug, PartialEq, Clone)]
 #[logos(skip r"[ \t\n\f]+", skip r"#.*\n?")]
 pub enum Token {
-    #[token("var")]
-    KeywordVar,
+    #[token("let")]
+    KeywordLet,
     #[token("print")]
     KeywordPrint,
+    #[token("fn")]
+    KeywordFn,
+    #[token("return")]
+    KeywordReturn,
 
-    #[regex("[_a-zA-Z][_0-9a-zA-Z]*", |lex| lex.slice().parse().ok())]
+    #[regex(r"_?\p{XID_Start}\p{XID_Continue}*", |lex| lex.slice().parse().ok())]
     Identifier(String),
     #[regex(r"\d+", |lex| lex.slice().parse().ok())]
-    Integer(i64),
+    Integer(String),
 
     #[token("(")]
-    LParen,
+    LeftParen,
     #[token(")")]
-    RParen,
+    RightParen,
+    #[token("{")]
+    LeftBracket,
+    #[token("}")]
+    RightBracket,
     #[token("=")]
     Assign,
     #[token(";")]
     Semicolon,
+    #[token(":")]
+    Colon,
+    #[token("->")]
+    Arrow,
+    #[token(",")]
+    Coma,
 
     #[token("+")]
     OperatorAdd,