On Sat, Jul 9, 2011 at 7:58 AM, Henning Thielemann <lemm...@henning-thielemann.de> wrote: > My stream processors are not Arrows, because 'first' cannot be implemented. > However, 'arr' and '.' can be implemented. ... > Since I have no Arrow instance I even have to write my own combinators that > are counterparts to (&&&) and friends.
If you have arr, (.) and (&&&), then you have first as well: f **** g = (arr fst >>> f) &&& (arr snd >>> g) first' f = f **** arr id Am I missing something here? =) Cheers, -- Felipe. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
