>> Remember that constructors are functions, except that you can't >> pattern match against them. > > .. > >> The downside is that you can't pattern-match against these functions. > > The thing is that I need pattern matching, just functions won't do.
It's "only" a preprocessor, but Conor's "she" allows pattern synonyms: http://personal.cis.strath.ac.uk/~conor/pub/she > Anyway, a new question arose. If I have already declared a type, can I add > new constructors to it from other modules? Again, not within Haskell itself. "she" also has a feature that allows something like this. There are various other techniques or proposals. For example: http://www.cs.ru.nl/~wouters/Publications/DataTypesALaCarte.pdf http://people.cs.uu.nl/andres/OpenDatatypes.html Cheers, Andres _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
