Add a unit test for the supercombinators

tests/eval.rkt

@@ -0,0 +1,30 @@
+#lang typed/racket
+(require "../semantics.rkt")
+(require "../ast.rkt")
+(require typed/rackunit)
+
+(: exp->program (-> CoreExpr CoreProgram))
+(define (exp->program i)
+  (list `(define (main) ,i)))
+
+(define-syntax ap-exp
+  (syntax-rules ()
+    [(ap-exp a) a]
+    [(ap-exp a b c ...)
+     (ap-exp (list a b) c ...)]))
+
+(: program-final-node (-> CoreProgram Node))
+(define (program-final-node prog)
+  (let* ([st (last (eval-state (compile-core prog)))]
+         [stack (State-stack st)]
+         [heap (State-heap st)])
+    (if (null? stack)
+        (error "impossible: not a final node")
+        (lookup-node heap (first stack)))))
+
+(: exp-final-node (-> CoreExpr Node))
+(define (exp-final-node e)
+  (program-final-node (exp->program e)))
+
+(check-equal? (exp-final-node (ap-exp 'S 'K 'K 3)) 3)
+(check-equal? (exp-final-node (ap-exp 'K 100 99)) 100)