1 files changed, 43 insertions, 0 deletions
diff --git a/src/lib/Xmobar/Plugins/Utils.hs b/src/lib/Xmobar/Plugins/Utils.hs
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+++ b/src/lib/Xmobar/Plugins/Utils.hs
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+------------------------------------------------------------------------------
+-- |
+-- Module: Plugins.Utils
+-- Copyright: (c) 2010 Jose Antonio Ortega Ruiz
+-- License: BSD3-style (see LICENSE)
+--
+-- Maintainer: Jose A Ortega Ruiz <jao@gnu.org>
+-- Stability: unstable
+-- Portability: unportable
+-- Created: Sat Dec 11, 2010 20:55
+--
+--
+-- Miscellaneous utility functions
+--
+------------------------------------------------------------------------------
+
+
+module Xmobar.Plugins.Utils (expandHome, changeLoop, safeHead) where
+
+import Control.Monad
+import Control.Concurrent.STM
+
+import System.Environment
+import System.FilePath
+
+
+expandHome :: FilePath -> IO FilePath
+expandHome ('~':'/':path) = fmap (</> path) (getEnv "HOME")
+expandHome p              = return p
+
+changeLoop :: Eq a => STM a -> (a -> IO ()) -> IO ()
+changeLoop s f = atomically s >>= go
+ where
+    go old = do
+        f old
+        go =<< atomically (do
+            new <- s
+            guard (new /= old)
+            return new)
+
+safeHead :: [a] -> Maybe a
+safeHead    [] = Nothing
+safeHead (x:_) = Just x