funclang series5: Added evaluation of conditional expression.

funclang-taddeus/series5/ass13.ml

@@ -40,7 +40,12 @@ let rec eval exp =
     | FunAp (e1, e2) -> (* prevent recursion *)
         let result = FunAp (eval e1, eval e2) in
         if result = exp then result else eval result
-    | Cond (cond, e1, e2) -> Cond (eval cond, eval e1, eval e2)
+    | Cond (cond, e1, e2) ->
+        (* If the condition evaluates to a boolean, choose the corresponding
+         * conditional expression *)
+        (match eval cond with
+          Bool b -> if b then eval e1 else eval e2
+        | c -> Cond (c, eval e1, eval e2))
     | Let (x, e1, e2) -> eval (subs e2 x e1)
     | LetRec (x, e1, e2) -> LetRec (x, eval e1, eval e2)
     | _ -> exp

funclang-taddeus/series5/test.ml

@@ -78,6 +78,8 @@ test_eval "true" (BinopAp (Or, Bool true, Bool false));;
 test_eval "fun u -> fun w -> fun a -> a" ass1a;;
 test_eval "(a (b c))" ass1b;;
 test_eval "c + b" (Let ("a", Var "c", (BinopAp (Add, Var "a", Var "b"))));;
+test_eval "a" (Cond (Bool true, Var "a", Var "b"));;
+test_eval "b" (Cond (Bool false, Var "a", Var "b"));;
 
 let x = Var "x" in
 let y = Var "y" in