diff --git a/src/compiler.rs b/src/compiler.rs
index 6f75bf1..b0586ea 100644
--- a/src/compiler.rs
+++ b/src/compiler.rs
@@ -4,6 +4,7 @@ use interpreter::interpret;
 use parser::parse;
 use symtab::SymTab;
 use tokenizer::tokenize;
+use type_checker::type_check;
 
 mod ast;
 mod interpreter;
@@ -11,12 +12,13 @@ mod parser;
 mod symtab;
 mod token;
 mod tokenizer;
-//mod type_checker;
+mod type_checker;
 mod variable;
 
 pub fn compile(code: &str) {
-    let tokens = tokenizer::tokenize(code);
-    parser::parse(&tokens);
+    let tokens = tokenize(code);
+    let ast = parse(&tokens);
+    type_check(&ast, &mut SymTab::new_type_table());
 }
 
 pub fn start_interpreter() {
@@ -27,7 +29,7 @@ pub fn start_interpreter() {
             let tokens = tokenize(&code);
             let ast = parse(&tokens);
 
-            let val = interpret(&ast, &mut SymTab::new());
+            let val = interpret(&ast, &mut SymTab::new_val_table());
             println!("{}", val);
         }
     }
diff --git a/src/compiler/interpreter.rs b/src/compiler/interpreter.rs
index 3db3870..24dcd07 100644
--- a/src/compiler/interpreter.rs
+++ b/src/compiler/interpreter.rs
@@ -4,7 +4,10 @@ use crate::compiler::{
     variable::Value,
 };
 
-pub fn interpret<'source>(ast: &Expression<'source>, symbols: &mut SymTab<'source>) -> Value {
+pub fn interpret<'source>(
+    ast: &Expression<'source>,
+    symbols: &mut SymTab<'source, Value>,
+) -> Value {
     match ast {
         EmptyLiteral(_) => Value::None(),
         IntLiteral(_, val) => Value::Int(*val),
diff --git a/src/compiler/symtab.rs b/src/compiler/symtab.rs
index 7d05ee1..dae6f66 100644
--- a/src/compiler/symtab.rs
+++ b/src/compiler/symtab.rs
@@ -1,13 +1,13 @@
-use crate::compiler::variable::Value;
+use crate::compiler::variable::{Type, Value};
 use std::collections::HashMap;
 
 #[derive(Default)]
-pub struct SymTab<'source> {
-    tables: Vec<HashMap<&'source str, Value>>,
+pub struct SymTab<'source, T> {
+    tables: Vec<HashMap<&'source str, T>>,
 }
 
-impl<'source> SymTab<'source> {
-    pub fn get(&mut self, symbol: &str) -> &mut Value {
+impl<'source, T> SymTab<'source, T> {
+    pub fn get(&mut self, symbol: &str) -> &mut T {
         for i in (0..self.tables.len()).rev() {
             if self.tables[i].contains_key(symbol) {
                 return self.tables[i].get_mut(symbol).unwrap();
@@ -16,28 +16,6 @@ impl<'source> SymTab<'source> {
         panic!("No symbol {} found!", symbol);
     }
 
-    pub fn new() -> SymTab<'source> {
-        let globals = HashMap::from([
-            ("+", Value::Func(Value::add)),
-            ("*", Value::Func(Value::mul)),
-            ("-", Value::Func(Value::sub)),
-            ("/", Value::Func(Value::div)),
-            ("%", Value::Func(Value::rem)),
-            ("==", Value::Func(Value::eq)),
-            ("!=", Value::Func(Value::neq)),
-            ("<", Value::Func(Value::lt)),
-            ("<=", Value::Func(Value::le)),
-            (">", Value::Func(Value::gt)),
-            (">=", Value::Func(Value::ge)),
-            ("not", Value::Func(Value::not)),
-            ("neg", Value::Func(Value::neg)),
-        ]);
-
-        SymTab {
-            tables: vec![globals],
-        }
-    }
-
     pub fn push_level(&mut self) {
         self.tables.push(HashMap::new());
     }
@@ -46,7 +24,7 @@ impl<'source> SymTab<'source> {
         self.tables.pop();
     }
 
-    pub fn insert(&mut self, name: &'source str, val: Value) {
+    pub fn insert(&mut self, name: &'source str, val: T) {
         if self
             .tables
             .last_mut()
@@ -58,3 +36,51 @@ impl<'source> SymTab<'source> {
         }
     }
 }
+
+impl<'source> SymTab<'source, Type> {
+    pub fn new_type_table() -> SymTab<'source, Type> {
+        use Type::*;
+        let globals = HashMap::from([
+            ("+", Func(vec![Int, Int], Box::new(Int))),
+            ("*", Func(vec![Int, Int], Box::new(Int))),
+            ("-", Func(vec![Int, Int], Box::new(Int))),
+            ("/", Func(vec![Int, Int], Box::new(Int))),
+            ("%", Func(vec![Int, Int], Box::new(Int))),
+            ("<", Func(vec![Int, Int], Box::new(Bool))),
+            ("<=", Func(vec![Int, Int], Box::new(Bool))),
+            (">", Func(vec![Int, Int], Box::new(Bool))),
+            (">=", Func(vec![Int, Int], Box::new(Bool))),
+            ("not", Func(vec![Bool], Box::new(Bool))),
+            ("neg", Func(vec![Bool], Box::new(Bool))),
+        ]);
+
+        SymTab {
+            tables: vec![globals],
+        }
+    }
+}
+
+impl<'source> SymTab<'source, Value> {
+    pub fn new_val_table() -> SymTab<'source, Value> {
+        use Value::*;
+        let globals = HashMap::from([
+            ("+", Func(Value::add)),
+            ("*", Func(Value::mul)),
+            ("-", Func(Value::sub)),
+            ("/", Func(Value::div)),
+            ("%", Func(Value::rem)),
+            ("==", Func(Value::eq)),
+            ("!=", Func(Value::neq)),
+            ("<", Func(Value::lt)),
+            ("<=", Func(Value::le)),
+            (">", Func(Value::gt)),
+            (">=", Func(Value::ge)),
+            ("not", Func(Value::not)),
+            ("neg", Func(Value::neg)),
+        ]);
+
+        SymTab {
+            tables: vec![globals],
+        }
+    }
+}
diff --git a/src/compiler/type_checker.rs b/src/compiler/type_checker.rs
new file mode 100644
index 0000000..d3ce620
--- /dev/null
+++ b/src/compiler/type_checker.rs
@@ -0,0 +1,208 @@
+use crate::compiler::{
+    ast::Expression::{self, *},
+    symtab::SymTab,
+    variable::Type,
+};
+
+pub fn type_check<'source>(ast: &Expression<'source>, symbols: &mut SymTab<'source, Type>) -> Type {
+    match ast {
+        EmptyLiteral(_) => Type::Unit,
+        IntLiteral(_, _) => Type::Int,
+        BoolLiteral(_, _) => Type::Bool,
+        Identifier(_, _) => todo!(),
+        UnaryOp(_, _, _) => todo!(),
+        BinaryOp(_, _, _, _) => todo!(),
+        VarDeclaration(_, _, _) => Type::Unit,
+        Conditional(_, _, _, _) => todo!(),
+        While(_, _, _) => todo!(),
+        FunCall(_, _, _) => todo!(),
+        Block(_, _) => todo!(),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::compiler::{parser::parse, tokenizer::tokenize};
+    use Type::*;
+
+    fn get_type(code: &str) -> Type {
+        type_check(&parse(&tokenize(code)), &mut SymTab::new_type_table())
+    }
+
+    #[test]
+    fn test_individual() {
+        let result = get_type("1");
+        assert_eq!(result, Int);
+
+        let result = get_type("true");
+        assert_eq!(result, Bool);
+
+        let result = get_type("var a = true; a");
+        assert_eq!(result, Bool);
+
+        let result = get_type("var a = true;");
+        assert_eq!(result, Unit);
+
+        let result = get_type("+");
+        assert_eq!(result, Func(vec![Int, Int], Box::new(Int)));
+    }
+
+    #[test]
+    fn test_var_untyped() {
+        let result = get_type("var a = 1");
+        assert_eq!(result, Unit);
+
+        let result = get_type("var a = 1; a");
+        assert_eq!(result, Int);
+    }
+
+    #[test]
+    fn test_var_typed() {
+        let result = get_type("var a: Int = 1");
+        assert_eq!(result, Unit);
+
+        let result = get_type("var a = 1; a");
+        assert_eq!(result, Int);
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_var_typed_mismatch() {
+        get_type("var a: Int = true");
+    }
+
+    #[test]
+    fn test_assign() {
+        let result = get_type("var a = 1; a = 2;");
+        assert_eq!(result, Unit);
+
+        let result = get_type("var a = 1; a = 2");
+        assert_eq!(result, Int);
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_assign_mismatch() {
+        get_type("var a = 1; a = true");
+    }
+
+    #[test]
+    fn test_operators() {
+        let result = get_type("true or false");
+        assert_eq!(result, Bool);
+        let result = get_type("true and false");
+        assert_eq!(result, Bool);
+        let result = get_type("true == false");
+        assert_eq!(result, Bool);
+        let result = get_type("1 == 2");
+        assert_eq!(result, Bool);
+        let result = get_type("true != false");
+        assert_eq!(result, Bool);
+        let result = get_type("1 != 2");
+        assert_eq!(result, Bool);
+        let result = get_type("1 < 2");
+        assert_eq!(result, Bool);
+        let result = get_type("1 <= 2");
+        assert_eq!(result, Bool);
+        let result = get_type("1 > 2");
+        assert_eq!(result, Bool);
+        let result = get_type("1 >= 2");
+        assert_eq!(result, Bool);
+        let result = get_type("1 + 2");
+        assert_eq!(result, Int);
+        let result = get_type("1 - 2");
+        assert_eq!(result, Int);
+        let result = get_type("1 * 2");
+        assert_eq!(result, Int);
+        let result = get_type("1 / 2");
+        assert_eq!(result, Int);
+        let result = get_type("1 % 2");
+        assert_eq!(result, Int);
+        let result = get_type("not false");
+        assert_eq!(result, Bool);
+        let result = get_type("-1");
+        assert_eq!(result, Int);
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_operators_mismatch() {
+        get_type("1 == true");
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_operators_wrong_type() {
+        get_type("1 and 2");
+    }
+
+    #[test]
+    fn test_conditional() {
+        let result = get_type("if true then 1");
+        assert_eq!(result, Unit);
+
+        let result = get_type("if true then 1 else 2");
+        assert_eq!(result, Int);
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_conditional_non_bool() {
+        get_type("if 1 then 2");
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_conditional_type_mismatch() {
+        get_type("if true then 2 else false");
+    }
+
+    #[test]
+    fn test_while() {
+        let result = get_type("while true do 1");
+        assert_eq!(result, Unit);
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_while_non_bool() {
+        get_type("while 1 do 2");
+    }
+
+    #[test]
+    fn test_block() {
+        let result = get_type("{1; 2}");
+        assert_eq!(result, Int);
+
+        let result = get_type("{1; 2;}");
+        assert_eq!(result, Unit);
+    }
+
+    #[test]
+    fn test_function() {
+        let mut tokens = tokenize("foo(1)");
+        let mut ast = parse(&tokens);
+        let mut symtab = SymTab::new_type_table();
+        symtab.insert("foo", Func(vec![Int], Box::new(Int)));
+        let result = type_check(&ast, &mut symtab);
+        assert_eq!(result, Int);
+
+        tokens = tokenize("foo(1);");
+        ast = parse(&tokens);
+        symtab = SymTab::new_type_table();
+        symtab.insert("foo", Func(vec![Int], Box::new(Int)));
+        let result = type_check(&ast, &mut symtab);
+        assert_eq!(result, Unit);
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_function_wrong_arg() {
+        let tokens = tokenize("foo(true)");
+        let ast = parse(&tokens);
+        let mut symtab = SymTab::new_type_table();
+        symtab.insert("foo", Func(vec![Int], Box::new(Int)));
+        type_check(&ast, &mut symtab);
+    }
+}
diff --git a/src/compiler/variable.rs b/src/compiler/variable.rs
index e4e8d97..bb4f925 100644
--- a/src/compiler/variable.rs
+++ b/src/compiler/variable.rs
@@ -1,5 +1,13 @@
 use std::fmt;
 
+#[derive(PartialEq, Debug)]
+pub enum Type {
+    Int,
+    Bool,
+    Func(Vec<Type>, Box<Type>),
+    Unit,
+}
+
 #[derive(PartialEq, PartialOrd, Debug, Copy, Clone)]
 pub enum Value {
     Int(i64),