diff --git a/schala-lang/src/builtin.rs b/schala-lang/src/builtin.rs
index e78eb7f..00a9d8e 100644
--- a/schala-lang/src/builtin.rs
+++ b/schala-lang/src/builtin.rs
@@ -63,15 +63,15 @@ lazy_static! {
 lazy_static! {
   static ref BINOPS: HashMap<&'static str, (Type, (), i32)> =
     hashmap! {
-      "+" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 10),
-      "-" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 10),
-      "*" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
-      "/" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Float))))), (), 20),
-      "//" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20), //TODO change this to `quot`
-      "%" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
+      "+" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 10),
+      "-" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 10),
+      "*" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "/" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Float))))), (), 20),
+      "//" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20), //TODO change this to `quot`
+      "%" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
       "++" => (Func(bx!(Const(StringT)), bx!(Func(bx!(Const(StringT)), bx!(Const(StringT))))), (), 30),
-      "^" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
-      "&" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
-      "|" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
+      "^" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "&" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "|" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
     };
 }
diff --git a/schala-lang/src/typechecking.rs b/schala-lang/src/typechecking.rs
index ab2a164..07d113a 100644
--- a/schala-lang/src/typechecking.rs
+++ b/schala-lang/src/typechecking.rs
@@ -34,15 +34,33 @@ pub struct Symbol {
 #[derive(Debug, PartialEq, Clone)]
 pub enum Type {
   Const(TConst),
-  Sum(Vec<Type>),
+  Var(TVar),
   Func(Box<Type>, Box<Type>),
   //UVar(String),
   //EVar(u64),
+  Sum(Vec<Type>),
   Void
 }
 
+#[derive(Debug, PartialEq, Clone)]
+pub struct TVar(String);
+
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum TConst {
+  Unit,
+  Nat,
+  Int,
+  Float,
+  StringT,
+  Bool,
+  Custom(String),
+}
+
 impl fmt::Display for Type {
   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    write!(f, "{:?}", self)
+    /*
     use self::Type::*;
     match self {
       &Const(ref c) => write!(f, "{:?}", c),
@@ -61,6 +79,7 @@ impl fmt::Display for Type {
       //&EVar(ref n) => write!(f, "{}_e", n),
       &Void => write!(f, "Void")
     }
+    */
   }
 }
 
@@ -82,17 +101,6 @@ impl UVarGenerator {
 }
 */
 
-#[derive(Debug, PartialEq, Clone)]
-pub enum TConst {
-  Unit,
-  Nat,
-  Int,
-  Float,
-  StringT,
-  Bool,
-  Custom(String),
-}
-
 //TODO get rid of this, just instantiate builtin types to the environment
 impl parsing::TypeName {
   fn to_type(&self) -> TypeResult<Type> {
@@ -274,15 +282,6 @@ impl TypeContext {
         }
         Ok(Sum(types))
       },
-      /*
-  Index {
-    indexee: Box<Expression>,
-    indexers: Vec<Expression>,
-  },
-  IfExpression(Box<Expression>, Vec<Statement>, Option<Vec<Statement>>),
-  MatchExpression(Box<Expression>, Vec<MatchArm>),
-  ForExpression
-      */
       _ => Err(format!("Type not yet implemented"))
     }
   }