Support for Type Language (#3593)

* Support for Type Language

* Update Type Language

* Add one more sample for Type Language

* Update Type Language grammar

samples/Type Language/builtin.tl

@@ -0,0 +1,39 @@
+// built-in types
+int#a8509bda ? = Int;
+long ? = Long;
+double ? = Double;
+string ? = String;
+null = Null;
+
+vector {t:Type} # [ t ] = Vector t;
+coupleInt {alpha:Type} int alpha = CoupleInt<alpha>;
+coupleStr {gamma:Type} string gamma = CoupleStr gamma;
+
+/* The name of the type variable is irrelevant: "gamma" could be replaced with "alpha"
+  However, the combinator number will depend on the specific choice. */
+
+intHash {alpha:Type} vector<coupleInt<alpha>> = IntHash<alpha>;
+strHash {alpha:Type} (vector (coupleStr alpha)) = StrHash alpha;
+intSortedHash {alpha:Type} intHash<alpha> = IntSortedHash<alpha>;
+strSortedHash {alpha:Type} (strHash alpha) = StrSortedHash alpha;
+
+// custom types
+pair x:Object y:Object = Pair;
+triple x:Object y:Object z:Object = Triple;
+
+user#d23c81a3 id:int first_name:string last_name:string = User;
+no_user#c67599d1 id:int = User;
+group id:int title:string last_name:string = Group;
+no_group = Group;
+
+---functions---
+
+// Maybe some built-in arithmetic functions; inverse quotes make "identifiers" out of arbitrary non-alphanumeric strings
+`+` Int Int = Int;
+`-` Int Int = Int;
+`+` Double Double = Double;
+// ...
+
+// API functions (aka RPC functions)
+getUser#b0f732d5 int = User;
+getUsers#2d84d5f5 (Vector int) = Vector User;