Create HPath.IO module, adding canonicalizePath again

hpath.cabal

@@ -22,6 +22,7 @@ library
   ghc-options:       -Wall -O2
   c-sources:         cbits/dirutils.c
   exposed-modules:   HPath,
+                     HPath.IO,
                      HPath.Internal,
                      System.Posix.Directory.Foreign,
                      System.Posix.Directory.Traversals,

src/HPath/IO.hs

@@ -0,0 +1,28 @@
+-- |
+-- Module      :  HPath.IO
+-- Copyright   :  © 2016 Julian Ospald
+-- License     :  BSD 3 clause
+--
+-- Maintainer  :  Julian Ospald <hasufell@posteo.de>
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- IO operations on HPath.
+
+{-# OPTIONS_HADDOCK ignore-exports #-}
+
+module HPath.IO
+  where
+
+
+import           HPath
+import           HPath.Internal
+import           System.Posix.Directory.Traversals (realpath)
+
+
+
+-- | May fail on `realpath`.
+canonicalizePath :: Path Abs -> IO (Path Abs)
+canonicalizePath (MkPath l) = do
+  nl <- realpath l
+  return $ MkPath nl