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diff --git a/src/SensibleDir.hs b/src/SensibleDir.hs
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+++ b/src/SensibleDir.hs
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+{-# LANGUAGE CPP #-}
+{-# LANGUAGE TupleSections #-}
+module SensibleDir where
+
+import Paths_testcabaldir
+import System.Directory
+#ifdef VERSION_directory_xdg
+import System.DirectoryXdg
+#endif
+import System.FilePath
+import System.IO
+import System.Info
+import System.Environment
+import Control.Arrow
+import Control.Applicative
+import Data.List
+
+installScenario = NotInstalled
+doit = do
+    ddir <- getDataDir
+    ldir <- getLibDir
+    pname <- getProgName
+    ppath <- getExecutablePath
+    sysconfdir <- getSysconfDir
+    putStrLn ("ddir = " ++ ddir);
+    putStrLn ("ldir = " ++ ldir);
+    putStrLn ("sysconfdir = " ++ sysconfdir);
+    putStrLn ("pname = " ++ pname);
+    putStr "runningInBuildDir = "
+    print =<< runningInBuildDir
+    putStr "detectLikelyInstall = "
+    print =<< detectLikelyInstall
+    putStrLn "---------------------"
+    putStr "sensibleCacheDir = "
+    print =<< sensibleCacheDir pname
+    -- putStr "sensibleConfigDir = "
+    -- print =<< sensibleConfigDir pname
+
+runningInBuildDir :: IO Bool
+runningInBuildDir = any (=="build") . take 2 . reverse . splitDirectories . takeDirectory <$> getExecutablePath
+    
+runningInCabalDir :: IO Bool
+runningInCabalDir = any (==".cabal") . take 2 . reverse . splitDirectories . takeDirectory <$> getExecutablePath
+
+runningInSysBin = do
+    exedir <- splitDirectories . takeDirectory <$> getExecutablePath
+    return $ 
+      case take 3 (drop 1 exedir) of
+        ["bin"]                -> True
+        ["sbin"]               -> True
+        ["usr","bin"]          -> True
+        ["usr","sbin"]         -> True
+        _ -> False
+
+runningInLocalBin = do
+    exedir <- splitDirectories . takeDirectory <$> getExecutablePath
+    putStr "exedir = "
+    print exedir
+    return $ 
+      case take 3 (drop 1 exedir) of
+        ["usr","local","bin"]  -> True
+        ["usr","local","sbin"] -> True
+        _ -> False
+
+-- scenarios
+data InstallScenario = PrefixInstall
+                     -- ^ installed in /opt or some other prefix, or running inside source folder
+                     | SystemInstall
+                     -- ^ installed system wide
+                     | LocalInstall
+                     -- ^ installed in /usr/local/
+                     | UserInstall
+                     -- ^ installed for a given user
+                     | NotInstalled
+                     -- ^ not installed, built by cabal or make, running from dist folder
+    deriving (Show,Enum,Eq)
+
+-- | careful, assumes unix-style FHS
+--   windows aware contributions welcome
+--   Detects the likely install scenario based on the path to the exectuable.
+detectLikelyInstall :: IO InstallScenario
+detectLikelyInstall = do
+    bBuildDir <- fmap (,NotInstalled) runningInBuildDir
+    bCabalDir <- fmap (,UserInstall)  runningInCabalDir
+    bLocalDir <- fmap (,LocalInstall) runningInLocalBin
+    bSysDir   <- fmap (,SystemInstall) runningInSysBin
+    case dropWhile (not . fst) [bBuildDir,bCabalDir,bLocalDir,bSysDir] of
+        (True,scenario):_ -> return scenario
+        _                 -> return PrefixInstall
+
+isUnix os = not $ "mingw" `isPrefixOf` os
+
+-- | Try to get the cache directory appropriate to the install scenario.
+--   On windows it just calls getAppUserDataDirectory and appends "cache". 
+--   (windows behavior subject to change, contributions welcome)
+sensibleCacheDir suffix = do
+    let ifunix x = if isUnix os then x
+                                else PrefixInstall
+    install <- ifunix <$> detectLikelyInstall
+    case install of
+        PrefixInstall -> do
+          if isUnix os
+           then do
+            dir <- splitDirectories . takeDirectory <$> getExecutablePath
+            let rdir = reverse dir
+            case take 1 rdir of
+                ["bin"] -> return $ (foldl1 combine $ reverse (drop 1 rdir)) </> "cache" </> suffix
+                _ -> fmap ((</> suffix) . (</> "cache") . takeDirectory) getExecutablePath
+           else getAppUserDataDirectory ("cache" </> suffix)
+        SystemInstall -> return ("/var/cache" </> suffix)
+        LocalInstall  -> return ("/var/local/cache" </> suffix)
+        UserInstall  -> getXdgDirectory XdgCache suffix
+        NotInstalled -> do
+            dir <- splitDirectories . takeDirectory <$> getExecutablePath
+            let rdir = reverse dir
+            return . foldl1 combine $ reverse ("cache": drop 2 rdir)
+
+-- | like 'sensibleCacheDir', but creates it if needed
+sensibleCacheDirCreateIfMissing suffix = do
+    dir <- sensibleCacheDir suffix
+    createDirectoryIfMissing True dir