From 00f82f1f9379eb86480ded59da31a37b83b779cc Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Thu, 20 Nov 2014 10:16:06 -0800
Subject: [PATCH] add sugar/cache module

---
 cache.rkt | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 cache.rkt

diff --git a/cache.rkt b/cache.rkt
new file mode 100644
index 0000000..c44f26b
--- /dev/null
+++ b/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 ...))]))
\ No newline at end of file