Am Donnerstag, 21. April 2005 12:37 schrieb Mike Richards:
Hi,
I'm working on a version of Simon Thompson's code from "The Craft of Functional
programming" to handle polymorhpic data types.
Heres the question Im working on - Ive tried doing the first part, but i would
really apprecate it if someone could let me know if ive implemented it wrong.
Mike
Could you be a little more precise on what you want to do? Without knowing that, I can say that - so far at least - the only used import is Char (perhaps better import Data.Char?), maybe also the Prelude, that seems no longer to be automatically imported in the new hugs version. Then you could use 'nub' from Data.List instead of list2set, dig2Int is digitToInt from Data.Char and a few more. matchPolyT doesn't work, it will return [] for any finite input, by the way, I couldn't figure out what 'Poly Type Type' is supposed to model. The instance declaration Eq Type is broken (Poly is the culprit) and in varParse you use 'spot' - why did you not adhere to Thompson's names in the first place? - and 'Var' which you didn't define. If I understand your goal, I'd be happy to help. Daniel