Hi, It sounds like your "use of `ioctl'' at topIO.hs:21:35-60" is passing an "Int" as the 3rd argument to "ioctl", when your instance declaration states that this argument should be a "C'winsize". -Iavor
On Wed, Nov 24, 2010 at 11:27 PM, Magicloud Magiclouds <magicloud.magiclo...@gmail.com> wrote: > Hi, > In System.Posix.IOCtl, there is such a class: > class Storable d => IOControl req d | req -> d where > ioctlReqSource :: req -> CInt > How to instance it? I do it as: > data TIOCGWINSZ = TIOCGWINSZ > > #starttype struct winsize > #field ws_row , CUShort > #field ws_col , CUShort > #field ws_xpixel , CUShort > #field ws_ypixel , CUShort > #stoptype > > instance IOControl TIOCGWINSZ C'winsize where > ioctlReq _ = #const TIOCGWINSZ > > Then I got: > topIO.hs:19:0: > Couldn't match expected type `C'winsize' > against inferred type `Int' > When using functional dependencies to combine > IOControl > (Foreign.C.Types.CUShort > -> Foreign.C.Types.CUShort > -> Foreign.C.Types.CUShort > -> Foreign.C.Types.CUShort > -> C'winsize) > Int, > arising from a use of `ioctl'' at topIO.hs:21:35-60 > IOControl > (Foreign.C.Types.CUShort > -> Foreign.C.Types.CUShort > -> Foreign.C.Types.CUShort > -> Foreign.C.Types.CUShort > -> C'winsize) > C'winsize, > arising from a use of `ioctl'' at topIO.hs:20:12-37 > When generalising the type(s) for `main' > -- > 竹密岂妨流水过 > 山高哪阻野云飞 > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
