Am 31.10.2010 16:53, schrieb Vo Minh Thu:
I can't really tell from your description, but maybe this is because of the way Parsec works when it deals with alternatives. When you combine several parsers with e.g. '<|>' or 'choice', an alternative that can consume some input but fails will make the whole combined parser fail too. So you have to either factorize you parsers or use the 'try'. See the documentation for 'try' at http://hackage.haskell.org/packages/archive/parsec/3.1.0/doc/html/Text-Parsec-Prim.html .
This is exactly what gives me headaches. It's hard to tell where you need try/lookAhead and where you don't need them. And I don't really feel comfortable wrapping everything into try blocks...
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
