On Jan 10, 2007, at 7:27 AM, Bulat Ziganshin wrote:
Hello David,
Wednesday, January 10, 2007, 5:35:03 AM, you wrote:
class List l e, l -> e where
(But I don't like functional dependencies, because they confuse me, and hope that associated types end up making it into Haskell'...)
well, it is pretty studied design space, you can look the chapter about fundeps in ghc 6.6 manual which describes various solutions for containers class problem
generally, we need either FD (which is not a part of Haskell') or AT (which is supported only by GHC HEAD)
about existing implementations:
1) Stringable class in fps-soc project. it is aimed to generalize interface of String and ButeString
2) numerous classes in Collections [2] and Edison [3] libraries
[1] http://darcs.haskell.org/SoC/fps-soc [2] http://darcs.haskell.org/packages/collections [3] http://www.eecs.tufts.edu/~rdocki01/projects/edison-1.2rc4- source.tar.gz
FYI, this is not the latest release of Edison. The latest release is available from: http://www.eecs.tufts.edu/~rdocki01/edison.html
-- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com
Rob Dockins Speak softly and drive a Sherman tank. Laugh hard; it's a long way to the bank. -- TMBG