On Mon, Jun 25, 2012 at 6:53 AM, Greg Weber
system-filepath looks slightly odd to be because I would have expected the representation internally to be platform-specific (e.g. either ByteString or Text for Unix or Windows respectively), but it just uses String.
I am kind of suprised to see an internal representation using strings also. I imagine that is because paths are usually used with system-fileio which needs strings for the existing Haskell APIs. system-fileio calls encodeString, which is OS specific, and that the internal code base is easier to maintain with 1 type. The encode/decode functions do return a platform specific type.
Having a single internal representation lets me avoid having to write all the path manipulation primitives twice. FilePaths use String so they can use the GHC 7.4 path encoding, which supports round-tripping for Unix and Windows paths. It has used other encodings (tried both Text and ByteString) in the past, but String+7.4 works well and is easier to use.