On Thu, Aug 19, 2010 at 6:26 AM, Ivan Lazar Miljenovic < ivan.miljenovic@gmail.com> wrote:
I'm trying to update container-classes to duplicate the pre-existing classes defined in the Prelude (Functor, etc.) and am trying to get my approach on how to have functions/classes that work on types of kind * (e.g. Bytestring) as well as kind * -> * (e.g. lists), as my previous approach didn't work.
This is exactly why the iteratee library provides a newtype wrapper around ByteString that adds a phantom type. If I recall correctly, it looks like this (and probably adds some derived instances): newtype WrappedByteString a = WBS ByteString Haskell isn't friendly when it comes to kind polymorphism and I've never really seen a "solution" for it that I like. And the above is actually something that may provide a nice addition to ByteString. You could track the encoding in the phantom type, potentially. Jason