From e54b15d63848461d1389b8eb143cf6af14b72ecb Mon Sep 17 00:00:00 2001
From: Don Stewart <dons@cse.unsw.edu.au>
Date: Mon, 30 Apr 2007 04:48:13 +0200
Subject: shrink 'swap'

darcs-hash:20070430024813-9c5c1-28d697989294c4c5ce03e44553b75a8d7bc6c03e.gz
---
 StackSet.hs | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

(limited to 'StackSet.hs')

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
 
 --
-- 
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