diff --git a/semantics.rkt b/semantics.rkt
index 22a3add..5712e5d 100644
--- a/semantics.rkt
+++ b/semantics.rkt
@@ -10,6 +10,14 @@
 (define-type Globals (Immutable-HashTable Name Addr))
 (define-type Stats Nonnegative-Integer)
 
+(: empty-heap Heap)
+(define empty-heap
+  (make-immutable-hash))
+
+(: empty-globals Globals)
+(define empty-globals
+  (make-immutable-hash))
+
 (: new-addr (-> Addr))
 (define (new-addr)
   (gensym))
@@ -23,6 +31,10 @@
 (: incr-stats (-> Stats Stats))
 (define incr-stats add1)
 
+(: update-globals (-> Globals Name Addr Globals))
+(define (update-globals globals name addr)
+  (hash-set globals name addr))
+
 (: update-stats (-> (-> Stats Stats) State State))
 (define (update-stats f mstate)
   (struct-copy State mstate [stats (f (State-stats mstate))]))
@@ -32,12 +44,11 @@
   (let ([addr (new-addr)])
     (values (hash-set heap addr node) addr)))
 
-(: allocate-sc (-> Heap CoreScDefn (Values Heap (Pair Name Addr))))
-(define (allocate-sc heap scdef)
-  (let-values ([(heap addr) (allocate-node heap scdef)])
-    (values heap (cons (scdefn-name scdef) addr))))
-
-
-;; (: initial-heap (-> (Listof CoreScDefn) (Values Heap Globals)))
-;; (define (initial-heap scs)
-;;   (for/fold ([heap ])))
+(: initialize-heap (-> (Listof CoreScDefn) (Values Heap Globals)))
+(define (initialize-heap scs)
+  (for/fold ([heap : Heap empty-heap]
+             [globals : Globals empty-globals])
+            ([sc : CoreScDefn scs])
+    (let-values ([(new-heap addr) (allocate-node heap sc)])
+      (values new-heap
+              (update-globals globals (scdefn-name sc) addr)))))