add sugar/cache module

cache.rkt

@@ -0,0 +1,15 @@
+#lang racket/base
+(require (for-syntax racket/base))
+(provide (all-defined-out))
+
+(define (make-caching-proc base-proc) 
+  (let ([cache (make-hash)])
+    (λ args
+      (hash-ref! cache args (λ () (apply base-proc args))))))
+
+(define-syntax (define/caching stx)
+  (syntax-case stx ()
+    [(_ (name arg ... . rest-arg) body ...)
+     #'(define/caching name (λ(arg ... . rest-arg) body ...))]
+    [(_ name body ...)
+     #'(define name (make-caching-proc body ...))]))