Re: Pattern guards vs. case (was, unfortunately :Re: interesting example of laziness/ghc optimisation)

But if you want to be really weird you can write something like (I haven't typed this in):

f x | (Foo _) == x = f x | (Bar _) == x =

no, you can't, e. g. hugs (Feb 2000) says Prelude> let f x | Just 4 == x = 0 in f (Just 4) 0 Prelude> let f x | Just _ == x = 0 in f (Just 4) ERROR: Illegal `_' in expression -- -- Johannes Waldmann ---- http://www.informatik.uni-leipzig.de/~joe/ -- -- joe@informatik.uni-leipzig.de -- phone/fax (+49) 341 9732 204/252 --