added len to interp_Ctup and type_check_Ctup

Author: jsiek

interp_Ctup.py

@@ -20,6 +20,9 @@ def interp_exp(self, e, env):
         return self.interp_exp(e, env)
       case GlobalValue(name):
         return 0 # bogus
+      case Call(Name('len'), [tup]):
+        t = self.interp_exp(tup, env)
+        return len(t)
       case _:
         return super().interp_exp(e, env)
 

type_check_Ctup.py

@@ -20,6 +20,15 @@ def type_check_exp(self, e, env):
               return Bottom()
             case _:
               raise Exception('error, expected a tuple, not ' + repr(tup_t))
+        case Call(Name('len'), [tup]):
+          tup_t = self.type_check_atm(tup, env)
+          match tup_t:
+            case TupleType(ts):
+              return int
+            case Bottom():
+              return Bottom()
+            case _:
+              raise Exception('error, expected a tuple, not ' + repr(tup_t))
         case _:
           return super().type_check_exp(e, env)