wip:

Add type system and refator for having only epression

examples/test_closure.lox

@@ -1,12 +1,12 @@
 
-closure :: fn() do
+closure :: fn(): Any do
     value := "Closure";
-    internal :: fn() do
+    internal :: fn(): String do
         print value;
         return value;
-    end
+    end;
     return internal;
-end
+end;
 
 internal := closure();
 internal();
@@ -17,9 +17,9 @@ c := b;
 c = b = a;
 d := c = b = a;
 do
-    showA :: fn() do
+    showA :: fn(): Nil do
         print a;
-    end
+    end;
 
     showA();
     a := "Local";