Alexander Dunlap wrote:
Hi all,
As we consider what we want to go into the Haskell Platform, I would like to seriously discuss the issue of container polymorphism, ... Thanks for your time in reading this admittedly long message,
Thanks for considering it! I think these are important issues; however, they're difficult ones that have been around for a while, and I don't think we'll be able to solve them quickly just because we're making a Haskell Platform. In some cases issues aren't as bad as they could be. If a library will take Lists of anything, then you can convert your type to a List. If its semantics mean it can only operate on bytes, then it can take lazy-ByteStrings (or Strict if it only operates on small things or if it can't stream data anyway)... Although it may be efficient, bytestrings work badly or not at all for non-byte data. Incidentally, at some point in the future, a decision may depend on what compiler-extensions we're willing to allow into the Platform (I suspect that a nice polymorphic solution [with possibly speed problems] basically requires Type Functions or equivalent..) -Isaac