From a07f0778add6d27fd1e89ca33dcc5b8a65a4ec41 Mon Sep 17 00:00:00 2001
From: Don Stewart <dons@cse.unsw.edu.au>
Date: Mon, 30 Apr 2007 02:48:13 +0000
Subject: [PATCH] shrink 'swap'

---
 StackSet.hs | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/StackSet.hs b/StackSet.hs
index 73c3bfb..a480792 100644
--- a/StackSet.hs
+++ b/StackSet.hs
@@ -202,14 +202,11 @@ promote w = maybe w id $ do
 -- > swap a b . swap a b == id
 --
 swap :: Eq a => a -> a -> [a] -> [a]
-swap a b xs
-    | a == b                    = xs    -- do nothing
-    | Just ai <- L.elemIndex a xs
-    , Just bi <- L.elemIndex b xs = insertAt bi a (insertAt ai b xs)
- where
-    insertAt n x ys = as ++ x : tail bs
-        where (as,bs) = splitAt n ys
-
+swap a b xs | a == b  = xs    -- do nothing
+            | Just ai <- L.elemIndex a xs
+            , Just bi <- L.elemIndex b xs = insertAt bi a (insertAt ai b xs)
+  where insertAt n x ys = as ++ x : tail bs
+            where (as,bs) = splitAt n ys
 swap _ _ xs = xs -- do nothing
 
 --