got type system working

examples/math/main.bl

@@ -1,14 +1,14 @@
 // adds a and b, but also 4 for some reason
-fn add(a: I32, b: I32): I32 {
+fn add(a: I64, b: I64): I64 {
     let foo = 4; // because I feel like it
-    let test_float: F32 = {
+    let test_float: F64 = {
       10.2
     };
     test_float = 5.0;
     a + b + foo
 }
 
-fn subtract(a: I32, b: I32): I32 {
+fn subtract(a: I64, b: I64): I64 {
     a - b
 }
 
@@ -25,10 +25,10 @@ fn i_hate_this(a: F64): F64 {
 }
 
 fn unit_function() {
-  let a: I32 = 4;
+  let a: I64 = 4;
 }
 
-fn main(): I32 {
+fn main(): I64 {
     add(4, subtract(5, 2))
 }
 
@@ -39,28 +39,28 @@ fn returns_user(): User {
     };
 }
 
-fn get_user_id(): U64 {
+fn get_user_id(): I64 {
     let user = returns_user();
     user.id = 5;
     return user.id;
 }
 
-fn use_method(user: User): U64 {
+fn use_method(user: User): I64 {
     return user.get_id();
 }
 
 type User struct {
-    id: U64,
+    id: I64,
 }
 
 impl User {
-    fn new(id: U64): Self {
+    fn new(id: I64): Self {
         return Self{
             id: id,
         };
     }
 
-    fn get_id(self: Self): U64 {
+    fn get_id(self: Self): I64 {
         return self.id;
     }
 }