From b30fe4409e50f05f90d050da8dc372e23c60edde Mon Sep 17 00:00:00 2001
From: Jason Creighton <jcreigh@gmail.com>
Date: Sun, 18 Mar 2007 00:49:04 +0100
Subject: basic xinerama support (depends on Graphics.X11.Xinerama in
 X11-extras)

darcs-hash:20070317234904-b9aa7-ef29cf597970298a24d770ec789f83638390d22a.gz
---
 StackSet.hs | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'StackSet.hs')

diff --git a/StackSet.hs b/StackSet.hs
index 15788bc..1453c97 100644
--- a/StackSet.hs
+++ b/StackSet.hs
@@ -61,6 +61,10 @@ empty n = StackSet { current = 0
 member :: Ord a => a -> StackSet a -> Bool
 member a w = M.member a (cache w)
 
+-- | /O(log n)/. Looks up the stack that x is in, if it is in the StackSet
+lookup :: (Monad m, Ord a) => a -> StackSet a -> m Int
+lookup x w = M.lookup x (cache w)
+
 -- | /O(n)/. Number of stacks
 size :: StackSet a -> Int
 size = M.size . stacks
-- 
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