Can't you just: instance Foo [a] where type Bar [_a] = Int
(At least I think I did that somewhere...) On Jan 16, 2016 9:24 PM, "Edward Kmett" <ekm...@gmail.com> wrote: > As a data point I now get thousands of occurrences of this warning across > my packages. > > It is quite annoying. > > class Foo a where > type Bar a > > instance Foo [a] where > type Bar [a] = Int > > is enough to trigger it. > > And you can't turn it off by using _ as > > instance Foo [_] where > type Bar [_] = Int > > isn't legal. > > I've been avoiding it for now by using > > if impl(ghc >= 8) > > ghc-options: -fno-warn-unused-matches > > but this is a pretty awful addition to this warning as it stands. > -Edward > > On Mon, Jan 11, 2016 at 2:12 PM, Henning Thielemann < > lemm...@henning-thielemann.de> wrote: > >> >> On Mon, 11 Jan 2016, Richard Eisenberg wrote: >> >> On Jan 9, 2016, at 6:44 PM, Henning Thielemann < >>> lemm...@henning-thielemann.de> wrote: >>> >>>> >>>> instance (Natural n) => Num.Integer (Un n) where >>>> type Repr (Un _n) = Unary >>>> >>>> >>>> GHC-7.6.3 and GHC-7.4.2 complain: >>>> Type indexes must match class instance head >>>> Found `Un _n' but expected `Un n' >>>> In the type synonym instance declaration for `Num.Repr' >>>> In the instance declaration for `Num.Integer (Un n)' >>>> >>>> >>>> GHC-7.8.4, GHC-7.10.3 and GHC-8.0 are happy with the difference. >>>> >>> >>> I'm surprised this is accepted at all. Looks like hogwash to me. I think >>> you should post a bug report. >>> >> >> Ok, but then GHC must not warn about the unused argument of Repr. >> >> _______________________________________________ >> Glasgow-haskell-users mailing list >> Glasgow-haskell-users@haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users >> > > > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users > >
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