That is annoying. I remember that there were people arguing that Monad should be used instead of Maybe but I don't remember the reasons. Personaly I feel quite happy with Maybe and I am using it in my own code. There should be a consistent approach in the different libraries or at least in a single package like "containers".
While googling for Zipper I also found this article: http://citeseer.ist.psu.edu/hinze01web.html Is this better alternative to Zipper? Have someone better experience with it? Regards, Krasimir On 5/23/08, Jules Bean <[EMAIL PROTECTED]> wrote: > Krasimir Angelov wrote: > > The monads design is used in Data.Map i.e. > > > > lookup :: (Monad m, Ord k) => k -> Map k a -> m a > > > > which is widely considered a poor design decision and a wart on Data.Map. > > :-) > > Seriously, if you don't return a useful error message, then Maybe is as good > as it gets, why not use it? > > (And there really is only one kind of error possible here, in each case) > > 'fail' only adds information in the case it has a useful error message (in > which case I'd encourage MonadError m =>) > > Jules > _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
