Hello, Bernard wrote: <<snip>> >But the problem is not solved (drum roll please). Even first time programmers >know the pitfalls of trying to show the empty list: > > show [] ---> kapow! > >But you ought to be able to print the empty list, >without having to make some bogus type qualification (which >is in general not a solution to the problem of printing arbitrary values).
But how about the difference between show ([] :: [Int] ) == "[]" show ([] :: [Char]) == "\"\"" and Prelude> (putStr.show) ([] :: [Int]) [] Prelude> (putStr.show) ([] :: [Char]) "" You probably want the first, but I want the second in the cases I'm working with strings. This problem is apparently not solved by simply adding a defaulting meganism for Show or Reify or whatever. It's not clear to me how much your proposal differs from extending the default meganism (http://www.haskell.org/onlinereport/decls.html#default-decls) to allow arbitrary classes, rather than only class Num, which would be more consistent with the current Haskell 98. Do Ghc and/or Hugs allow other defaults then Num already? Regards, Rijk-Jan van Haaften _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
