On Wed, Jan 13, 2010 at 4:59 AM, Brandon S. Allbery KF8NH <allb...@ece.cmu.edu> wrote: > On Jan 13, 2010, at 05:54 , David Virebayre wrote: >> >> On Wed, Jan 13, 2010 at 12:29 AM, Evan Laforge <qdun...@gmail.com> wrote: >>> >>> Occasionally I have a function with an unused argument, whose type I >>> don't want to restrict. Thus: >>> >>> f :: _unused -> A -> B >>> f _ a = b >> >> I probably misunderstood the problem, why not f:: a -> A -> B > > > He's looking for the self-documentation aspect of "this argument is > completely irrelevant". Neither rolling a random unused type variable nor > "forall"ing it (my first idea) really accomplishes that. >
Isn't that what we have here? a function of type (a -> A -> B) cannot use the first argument in any meaningful way. But once you start throwing in higher ranked types you might have to think a bit to come to that conclusion. Antoine _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe