Ivano, You are right; and we have to remind whoever is willing to listen that:
Kleisli category is defined for a monad. This fact can be found in "Categories for the Working Mathematicians", if the voice of reason is not enough. Thanks, -Vlad On Fri, Oct 20, 2017 at 10:40 AM, pagoda_5b <ivano.pag...@gmail.com> wrote: > I don't understand if you're asking how to implement compose as a > primitive on List, or if you're generally asking what opinion we have on > defining compose as one of the building blocks for the other operations... > > Apart from this, the different definitions are equivalent, in the sense > that to be able to define the kleisli composition for the Functor F, there > must be some underlying ability to define for F operations which are > equivalent to unit + join, or unit + flatMap, because that underlying > capability is what makes it possible for the corresponding Kleisli to be a > category and therefore to have a compose function. > > I know it may sounds a bit vague, but the corresponding math is what gives > meaning to the Monad definition and the operations on that. > > I hope it helps, otherwise feel free to elaborate more > > Ivano > > > On Thursday, August 31, 2017 at 7:54:33 PM UTC+2, Philip Schwarz wrote: >> >> >> <https://lh3.googleusercontent.com/-nrhmLl4SP6g/WahMoxJJ4eI/AAAAAAAAAyg/lfvzmXSxjVMNYQZfktc_U2HLCSNhK0sngCLcBGAs/s1600/Screen%2BShot%2B2017-08-28%2Bat%2B09.06.51.png> >> >> >> <https://lh3.googleusercontent.com/-asXR3bIZX34/WahMf_tFBjI/AAAAAAAAAyc/WcG5YNJeSPADZ8X9ahbVq_Oa57aVRpiXgCLcBGAs/s1600/Screen%2BShot%2B2017-08-28%2Bat%2B09.06.42.png> >> >> Hello, >> >> >> I have put together three slides capturing how https://www.manning.com/bo >> oks/functional-programming-in-scala defines a monad in terms of primitive >> combinators unit+flatMap, unit+compose and unit+map+join: https://twitter >> .com/philip_schwarz/status/902083644797399040 >> >> >> <https://lh3.googleusercontent.com/-9pLJ_MRbw3M/WahMKIrqsLI/AAAAAAAAAyY/V5lkL5B_mlA_vbejtUuM_vlRx0YhVkZsACLcBGAs/s1600/Screen%2BShot%2B2017-08-28%2Bat%2B09.06.33.png> >> >> >> >> <https://lh3.googleusercontent.com/-asXR3bIZX34/WahMf_tFBjI/AAAAAAAAAyc/WcG5YNJeSPADZ8X9ahbVq_Oa57aVRpiXgCLcBGAs/s1600/Screen%2BShot%2B2017-08-28%2Bat%2B09.06.42.png> >> >> >> >> <https://lh3.googleusercontent.com/-nrhmLl4SP6g/WahMoxJJ4eI/AAAAAAAAAyg/lfvzmXSxjVMNYQZfktc_U2HLCSNhK0sngCLcBGAs/s1600/Screen%2BShot%2B2017-08-28%2Bat%2B09.06.51.png> >> >> >> >> As you can see on the slide for unit+compose, the implementation of >> compose (Kleisli composition), for the list monad in this case, is left >> unspecified. In the answers to the book's exercises I have found an >> implementation of compose in terms of flatMap https://github.com/fpi >> nscala/fpinscala/blob/master/answerkey/monads/07.answer.scala >> <https://www.linkedin.com/redir/redirect?url=https%3A%2F%2Fgithub%2Ecom%2Ffpinscala%2Ffpinscala%2Fblob%2Fmaster%2Fanswerkey%2Fmonads%2F07%2Eanswer%2Escala&urlhash=Bz31&_t=tracking_anet>, >> but what does composition look like as a primitive? >> >> Any thoughts? >> >> Thanks, >> >> Philip Schwarz >> > -- > You received this message because you are subscribed to the Google Groups > "scala-functional" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to scala-functional+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "scala-functional" group. To unsubscribe from this group and stop receiving emails from it, send an email to scala-functional+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
