The conditionally set PLATFORM_PATH_FORMAT is exposed in a fairly poor way to the user making it easy to run into builds that are ironically platform dependent.

If you unknowingly use a function that returns PLATFORM_PATH_FORMAT such as encode :: FilePath -> PLATFORM_PATH_FORMAT, rather than encodeString or fromText, when you compile the same code on a different platform you invariably end up with a broken build, due to an error like: Couldn't match expected type ByteString with Text (or vice versa).

Perhaps hiding the PLATFORM_PATH_FORMAT from the user entirely, or make use of some other abstraction which is independent of the compilation platform.