* Stephen Tetley <stephen.tet...@gmail.com> [2013-04-16 19:48:47+0100] > On 16 April 2013 16:12, Alejandro Serrano Mena <trup...@gmail.com> wrote: > > Hi, > > First of all, let me say that this work on matchers is really useful :) > > > > Following Roman advice, I'm trying to find a more principled approach > > that could be useful for this library. It seems that "Match" could > > easily be converted to Either and thus made into Functor, Applicative, > > Alternative and Monad. That would allow to write things like: > > > > > Have you seen Ralf Hinze, Johan Jeuring and Andreas Loeh's paper on > Contracts? > > The found their Contract datatype formed a comonad - at the time this > seemed to be one of the few (non-synthetic) uses of comonads.
Their Contract datatype is contravariant, just like Tom's Matcher. So it cannot be a comonad. It's their "contracted function" type which is a (very simple) comonad — but I'm not sure how it can be useful here. (I only skipped very quickly through the paper, so I may be missing something.) Roman _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
