Fix the bug of not using the get-arg function

semantics.rkt

@@ -76,6 +76,13 @@
     (State (list (lookup-globals globals 'main)) empty-dump heap globals empty-stats)))
 
 
+(: eval-state (-> State (Pairof State (Listof State))))
+(define (eval-state st)
+  (if (final-state? st)
+      (list st)
+      (let ([next-st (update-stats incr-stats (step st))])
+        (cons st (eval-state next-st)))))
+
 (: data-node? (-> Node Boolean))
 (define data-node? integer?)
 
@@ -101,6 +108,12 @@
     [(list 'define (list name args ...) body)
      (step-sc rstack st args body)]))
 
+(: get-arg (-> Heap Addr Addr))
+(define (get-arg heap addr)
+  (match (lookup-node heap addr)
+    [(list _ a) a]
+    [_ (error "Not an application node")]))
+
 (: step-sc (-> Stack State (Listof Name) CoreExpr State))
 (define (step-sc rstack state arg-names body)
   (let ([heap (State-heap state)])
@@ -110,7 +123,7 @@
                             ([arg-name : Name arg-names])
                     (if (null? stack)
                         (error "Not enough arguments to apply the supercombinator")
-                        (values (update-globals globals arg-name (car stack)) (cdr stack))))]
+                        (values (update-globals globals arg-name (get-arg heap (car stack))) (cdr stack))))]
                   [(new-heap addr) (instantiate-body body new-env heap)])
       (let ([new-stack (cons addr new-stack)])
         (struct-copy State state [stack new-stack] [heap new-heap])))))