Finish 2.rkt

Final/2.rkt

@@ -8,6 +8,7 @@
   [errorE (msg : String)] ;; New
   [if0E (test : Exp) (then : Exp) (else : Exp)]
   [minus1E (n : Exp)]
+  [timesE (lhs : Exp) (rhs : Exp)]
   )
 
 (define-type Value
@@ -45,6 +46,11 @@
   [doMinusK (v1 : Value)
             (k : Continuation)]
   [doMinus1K (k : Continuation)]
+  [timesSecondK (r : Exp)
+                (env : Env)
+                (k : Continuation)]
+  [doTimesK (v1 : Value)
+            (k : Continuation)]
   [appArgK (arg-expr : Exp)
            (env : Env)
            (k : Continuation)]
@@ -85,6 +91,7 @@
        (case (s-exp->symbol (sx-ref sx 0))
          [(+) (plusE (px 1) (px 2))]
          [(-) (minusE (px 1) (px 2))]
+         [(*) (timesE (px 1) (px 2))]
          [(if0) (if0E (px 1) (px 2) (px 3))]
          [else (parse-error sx)])]
       [else (parse-error sx)])))
@@ -116,6 +123,7 @@
     [(if0E test-expr then-expr else-expr)
      (interp test-expr env (doIfK then-expr else-expr env k))]
     [(minus1E n) (interp n env (doMinus1K k))]
+    [(timesE l r) (interp l env (timesSecondK r env k))]
     ))
 
 (define (continue [k : Continuation] [v : Value]) : Value
@@ -131,6 +139,10 @@
      (continue next-k (arith-op - v1 v))]
     [(doMinus1K next-k)
      (continue next-k (arith-op - v (numV 1)))]
+    [(timesSecondK r env next-k)
+     (interp r env (doTimesK v next-k))]
+    [(doTimesK v1 next-k)
+     (continue next-k (arith-op * v1 v))]
     [(appArgK arg-expr env next-k)
      (interp arg-expr env (doAppK v next-k))]
     [(doAppK fun-val next-k)