14 Apr
2009
14 Apr
'09
5:43 a.m.
Unfortunately, this isn't supported at present. --Ben On 14 Apr 2009, at 05:28, Norman Ramsey wrote:
I've got a fairly large GADT for which I wished to use deriving (Show) but I got a mysterious error message:
Exp.hs:13:11: Can't make a derived instance of `Show (Exp a)' (`Exp' has non-Haskell-98 constructor(s)) In the data type declaration for `Exp'
This is from GHC. Does anybody know a compiler option or other trick that will coax the compiler into producing a Show instance. (I know I can write one by hand, but I'd rather not bother.)
Norman _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell