[Haskell-cafe] Why Kleisli composition is not in the Monad signature?
jake.mcarthur at gmail.com
Mon Oct 15 17:39:20 CEST 2012
On Mon, Oct 15, 2012 at 11:33 AM, Jake McArthur <jake.mcarthur at gmail.com> wrote:
> On Mon, Oct 15, 2012 at 7:59 AM, Ertugrul Söylemez <es at ertes.de> wrote:
>> Try to express
>> do x <- getLine
>> y <- getLine
>> print (x, y)
>> using only Kleisli composition (without cheating).
My previous answer didn't do the Kleisli style much justice. It could
look a bit nicer with more Arrow-style combinators:
f &=& g = runKleisli $ Kleisli f &&& Kleisli g
print <=< const getLine &=& const getLine $ ()
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