From abd302a839076d26e5abd516378fb9740973fed8 Mon Sep 17 00:00:00 2001
From: AlexKnauth <alexander@knauth.org>
Date: Thu, 27 Aug 2015 17:54:45 -0400
Subject: [PATCH] split functional-set? predicate into separate module

---
 lens/private/util/functional-set.rkt | 17 +++++++++++++++++
 unstable/lens/set-filterer.rkt       | 12 +-----------
 2 files changed, 18 insertions(+), 11 deletions(-)
 create mode 100644 lens/private/util/functional-set.rkt

diff --git a/lens/private/util/functional-set.rkt b/lens/private/util/functional-set.rkt
new file mode 100644
index 0000000..4fe1613
--- /dev/null
+++ b/lens/private/util/functional-set.rkt
@@ -0,0 +1,17 @@
+#lang sweet-exp racket/base
+
+provide functional-set?
+
+require racket/set
+module+ test
+  require rackunit
+
+(define (functional-set? st)
+  (and (generic-set? st)
+       (set-implements? st 'set-add 'set-remove)
+       (not (set-mutable? st))))
+
+module+ test
+  (check-true (functional-set? (set 1 2 3)))
+  (check-true (functional-set? '(1 2 3)))
+  (check-false (functional-set? (mutable-set 1 2 3)))
diff --git a/unstable/lens/set-filterer.rkt b/unstable/lens/set-filterer.rkt
index d941b01..76940ae 100644
--- a/unstable/lens/set-filterer.rkt
+++ b/unstable/lens/set-filterer.rkt
@@ -7,6 +7,7 @@ provide
     set-filterer-lens (-> predicate/c (lens/c functional-set? functional-set?))
 
 require lens/private/base/main
+        lens/private/util/functional-set
         racket/set
         racket/function
         fancy-app
@@ -51,14 +52,3 @@ module+ test
                 (set 4 5 6 7 'a 'b 'c 'd 'e))
   (check-exn exn:fail:contract?
              (thunk (lens-set (set-filterer-lens number?) (set 1) (set 'a))))
-
-
-(define (functional-set? st)
-  (and (generic-set? st)
-       (set-implements? st 'set-add 'set-remove)
-       (not (set-mutable? st))))
-
-module+ test
-  (check-true (functional-set? (set 1 2 3)))
-  (check-true (functional-set? '(1 2 3)))
-  (check-false (functional-set? (mutable-set 1 2 3)))