Simon Peyton-Jones [EMAIL PROTECTED] writes: > [.. following up to Peter Thiemann's post on the slowness of Read(S) ..]
> I do agree with you that it woud be better for the Read class > to use a Maybe result rather than a list of parses. But I'm not > sure your problem can be solved simply by making the Char > instance of Read better. .... For what it's worth, I played around with changing ReadS to do just that a couple of years ago, i.e., defining it as type ReadS a = String -> Maybe (a,String) The reductions in space&time were decent (at least 2x in some cases, if I remember correctly), but I didn't take the idea any further. It's a simple change - you can enable it by compiling GHC's PrelRead.lhs with the extra option -DNEW_READS_REP -- there's no 'deriving' support for this rep. of ReadS in the compiler itself tho. --sigbjorn _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
