funclang series5: Fixed mathematical evaluations combied with variables.

funclang-taddeus/series5/ass13.ml

@@ -3,27 +3,14 @@
 (* Perform all possible beta-reductions on an expression until the normal form
  * has been reached *)
 let rec eval exp =
-    let get_int_value = function
-          Num i -> i
-        | _ -> raise (Failure "Not an integer")
+    let eval_monop = function
+          (Neg, Num i) -> Num (-i)
+        | (Not, Bool b) -> Bool (not b)
+        | _ -> raise (Failure "Unknown unary operator")
     in
-    let get_bool_value = function
-          Bool b -> b
-        | _ -> raise (Failure "Not a boolean")
-    in
-    let eval_monop op a = match op with
-          Neg -> Num (- (get_int_value a))
-        | Not -> Bool (not (get_bool_value a))
-    in
-    let eval_binop op x y = match op with
-          And | Or ->
-            let a = get_bool_value x in
-            let b = get_bool_value y in
-            Bool (if op = And then a && b else a || b)
-        | _ ->
-            let a = get_int_value x in
-            let b = get_int_value y in
-            (match op with
+    let eval_binop binop = match binop with
+          (op, Num a, Num b) -> (match op with
+            (* Arithmethic or relational operation is possible on numbers *)
               Add -> Num (a + b)
             | Sub -> Num (a - b)
             | Mul -> Num (a * b)
@@ -35,11 +22,16 @@ let rec eval exp =
             | Le -> Bool (a <= b)
             | Gt -> Bool (a > b)
             | Ge -> Bool (a >= b)
-            | _ -> raise (Failure "Unknown operator"))
+            | _ -> raise (Failure "Unknown arithmetic/relational operator"))
+        | (op, Bool a, Bool b) -> (match op with
+            (* Locical operation is possible on booleans *)
+              And | Or -> Bool (if op = And then a && b else a || b)
+            | _ -> raise (Failure "Unknown locical operator"))
+        | (op, e1, e2) -> BinopAp (op, eval e1, eval e2)
     in
     match exp with
-      MonopAp (op, e) -> eval_monop op (eval e)
-    | BinopAp (op, e1, e2) -> eval_binop op (eval e1) (eval e2)
+      MonopAp (op, e) -> eval_monop (op, eval e)
+    | BinopAp (op, e1, e2) -> eval_binop (op, e1, e2)
     | Fun (x, e) -> Fun (x, eval e)
     | FunAp (Fun (x, Var y), a) when y = x -> eval a (* identity function *)
     | FunAp (Fun (y, e), a) -> (* prevent recursion *)

funclang-taddeus/series5/test.ml

@@ -87,3 +87,6 @@ let x = Var "x" in
 let y = Var "y" in
 let z = Var "z" in
 show_eval (app (l "x" (l "y" (l "z" (app (app x y) z)))) y);;
+
+(* c + b *)
+show_eval (Let ("a", Var "c", (BinopAp (Add, Var "a", Var "b"))));;