???

Assignments/01.rkt

@@ -70,7 +70,7 @@
 (test/exn (lookup 'x mt-env) "not bound")
 
 ; Needs to return new environment, with the boxed value containing the function, and a recursive reference to the same environment
-(define (extend-rec [env : Env] [sym : Symbol] [exp : Exp])
+(define (extend-rec env sym exp)
   (local [(define self (extend env sym (funV sym exp env)))]
     (type-case (Optionof (Boxof Value)) (hash-ref self sym)
       [(none) self]
@@ -104,11 +104,11 @@
           (interp b (extend f-env v av))]  ;; changed
          [else (error 'app "not a function")]))]
     [(let1E var val body)
-     (let ([new-env (extend nv
-                            var
-                            (interp val nv))])
+     (let ([new-env (extend nv var (interp val nv))])
        (interp body new-env))]
-    [(recE var val body) ....]))
+    [(recE var val body)
+     (let ([rec-env (extend-rec nv var val)])
+       (interp body rec-env))]))
 
 (run : (S-Exp -> Value))
 (define (run s)