From 7d76d71dc236eb709c63176609a6c54d207c562d Mon Sep 17 00:00:00 2001
From: Jack Firth <jackhfirth@gmail.com>
Date: Wed, 8 Jul 2015 01:25:32 -0700
Subject: [PATCH] Add contracts to core

---
 lens/base/base.rkt | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/lens/base/base.rkt b/lens/base/base.rkt
index 13b771a..70b3750 100644
--- a/lens/base/base.rkt
+++ b/lens/base/base.rkt
@@ -6,10 +6,13 @@
   (require rackunit))
 
 (provide let-lens
-         make-lens
-         focus-lens
-         use-applicable-lenses!
-         (rename-out [lens-struct? lens?]))
+         (contract-out [make-lens (-> (-> any/c any/c)
+                                      (-> any/c any/c any/c)
+                                      lens?)]
+                       [focus-lens (-> lens? any/c
+                                       (values any/c (-> any/c any/c)))]
+                       [use-applicable-lenses! (-> void?)]
+                       [lens? predicate/c]))
 
 
 (define lenses-applicable? (make-parameter #f))
@@ -28,6 +31,7 @@
   (require rackunit)
   (check-exn exn:fail? (thunk (first-lens '(a b c)))))
 
+(define lens? lens-struct?)
 
 (define (make-lens getter setter)
   (lens-struct getter setter))