The current directory is ".", not "" (GHC bug #2034) (patch version 2)    So now         splitFileName "foo" = ("./", "foo")
The current directory is ".", not "" (GHC bug #2034) (patch version 2)
  
So now
        splitFileName "foo" = ("./", "foo")

which gives us the additional property that

> Valid x => isValid (fst (splitFileName x))

This property is important, because it means that we can pass the
result of takeDirectory to any of the functions in System.Directory,
whereas previously we would have to check for the empty case first.

After discussion on the libraries list, I removed the second part of
the original change:

        "." </> x = x

This small bit of normalisation was there to ensure that the property

> Valid x => uncurry </> (splitFileName x) == x

still held.  However, it was arguably inconsistent (see the
discussion).  Now this property has an exception:

> Valid x => uncurry (</>) (splitFileName x) == x || fst (splitFileName x) == "./"

This is a small price to pay to gain the new property above.

thomie/filepath