Hi Benedikt, So what you are pointing out is the "is a" vs. "has a" dichotomy? To an extent, I see your point. I could argue that the semantics of the word "implements" perhaps leaves a bit of so-called wiggle room on the is a/has a subject. This could devolve into a long discussion of the most semantically correct place to use "implements Arity*" vs. "extends Arity*" throughout the API, but the final result, IMO, is that the intent of any given concrete class is clear enough, and Arity|Nullary|Unary|Binary|ad infinitum seems more convenient than e.g. "SomethingThatHasArity", etc.
Does that make sense? Matt On Tue, Feb 12, 2013 at 7:29 AM, Benedikt Ritter <brit...@apache.org> wrote: > Hi Guys, > > I've had a look at the github repo and let me say at first that I'm no > expert in functional programming. So maybe what I'm talking is complete > nonsense :) > > From what I learned about the concept of arity at wikipedia it seems that > an arity is a property of a functor. > One could say: "A binary functor has an arity of two" (right?!) > > In the github repo you introduced an inheritance relationship between > functors and arity. > This maybe a good thing to do from a pracmatic POV because all functors > share the fact that say have an arity. > > From an object oriented POV inheritance is more then pure reuse. When > defining an inheritance relationship between concept Super and concept Sub > we basically say "Every instance of Sub is also an instance of Super" or > short "Every Sub is also a Super" > > Now coming back to functors you have introduced a relationship that says > "Every BinaryFunction is a Binary and every Binary is an Arity". > Keeping in mind that arity is only a property of a functor (rather than a > superset) this seems strange (from an OO POV). > But as I'm no expert on functional programming this maybe the right thing > to do... :) > > just my 2 cents :) > Benedikt > > > > 2013/2/11 Bruno P. Kinoshita <ki...@apache.org> > > > Hi Matt! > > > > Great! I'll commit these changes tomorrow if there are no objections. > > > > Thanks! > > > > Bruno P. Kinoshita > > http://kinoshita.eti.br > > http://tupilabs.com > > > > > > ----- Original Message ----- > > > From: Matt Benson <gudnabr...@gmail.com> > > > To: Commons Developers List <dev@commons.apache.org> > > > Cc: > > > Sent: Monday, February 11, 2013 8:39 PM > > > Subject: Re: [functor] Change default arity of Function, Predicate and > > Procedure > > > > > > Hi Bruno, > > > No objections here about the Arity interfaces. I see that your > master > > > branch also contains changes to migrate Unary* to * and * to Nullary*. > > > Personally I am satisfied to align with lambda/guava if noone else > > objects. > > > > > > Thanks, > > > Matt > > > > > > > > > On Mon, Feb 11, 2013 at 4:25 PM, Bruno P. Kinoshita < > > > brunodepau...@yahoo.com.br> wrote: > > > > > >> Hi Matt, all, > > >> > > >> I'm messing with [functor] in my GitHub mirror [1]. You can find the > > >> commits in the master branch [2]. > > >> > > >> The Arity->Unary/Binary/Nullary interfaces look good. If there are no > > >> objections I would like to commit this change to the trunk in SVN. > > >> > > >> There are other changes that I'll omit in this commit, but will start > > > new > > >> threads here in the mailing list :o) > > >> > > >> Thank you in advance! > > >> > > >> [1] https://github.com/kinow/functor > > >> [2] https://github.com/kinow/functor/commits/master > > >> > > >> Bruno P. Kinoshita > > >> http://kinoshita.eti.br > > >> http://tupilabs.com > > >> > > >> > > >> >________________________________ > > >> > From: Bruno P. Kinoshita <ki...@apache.org> > > >> >To: Commons Developers List <dev@commons.apache.org>; " > > >> gudnabr...@gmail.com" <gudnabr...@gmail.com> > > >> >Sent: Wednesday, January 30, 2013 3:58 PM > > >> >Subject: Re: [functor] Change default arity of Function, Predicate > and > > >> Procedure > > >> > > > >> >I think it makes sense and is clear what is does. > > >> > > > >> >I thought in using {arity}Operation, but in Java 8 there are > > interfaces > > >> like BinaryOperator, and BinaryOperator extends BiFunction, so it > > would be > > >> confusing to users having something like interface BinaryFunction > > extends > > >> BinaryOperation in [functor]. > > >> > > > >> >Bruno P. Kinoshita > > >> >http://kinoshita.eti.br > > >> >http://tupilabs.com > > >> > > > >> > > > >> >----- Original Message ----- > > >> >> From: Matt Benson <gudnabr...@gmail.com> > > >> >> To: Bruno P. Kinoshita <brunodepau...@yahoo.com.br> > > >> >> Cc: Commons Developers List <dev@commons.apache.org> > > >> >> Sent: Wednesday, January 30, 2013 1:29 PM > > >> >> Subject: Re: [functor] Change default arity of Function, Predicate > > > and > > >> Procedure > > >> >> > > >> >> What about: > > >> >> > > >> >> Arity (Marker) > > >> >> |_Nullary extends Arity > > >> >> |_Unary<A> extends Arity > > >> >> |_Binary<L, R> extends Arity > > >> >> > > >> >> ? > > >> >> > > >> >> Matt > > >> >> > > >> >> > > >> >> On Tue, Jan 29, 2013 at 6:09 PM, Bruno P. Kinoshita < > > >> >> brunodepau...@yahoo.com.br> wrote: > > >> >> > > >> >>> In Haskell you define your functions and its arity. > > >> >>> > > >> >>> // nullary function > > >> >>> a :: () => () -> String > > >> >>> a = "Hello World" > > >> >>> > > >> >>> // unary function > > >> >>> b :: (Integral c) => c -: String > > >> >>> b x = "Hello Integral" > > >> >>> > > >> >>> I think in Clojure and Scala you can define the arity of the > > > function > > >> too. > > >> >>> > > >> >>> For the users of [functor] I think it would be easier to > > > migrate their > > >> >>> code to Java 8, or use it with Java 8, if both [functor] and > > > Java 8 > > >> >>> Function classes had similar behaviour. That would be > > > interesting > > >> >>> especially if the lambda project provided a backport jar. > > >> >>> > > >> >>> [functor] and lambda project provide 1 and 2 arities by > > > default, but > > >> >>> lambda doesn't provide nullary interfaces (or at least I > > > couldn't > > >> >> find them > > >> >>> in java.util.functions). > > >> >>> > > >> >>> Cheers > > >> >>> > > >> >>> Bruno P. Kinoshita > > >> >>> http://kinoshita.eti.br > > >> >>> http://tupilabs.com > > >> >>> > > >> >>> > > >> >>> ----- Original Message ----- > > >> >>> > From: Matt Benson <gudnabr...@gmail.com> > > >> >>> > To: Commons Developers List > > > <dev@commons.apache.org>; Bruno P. > > >> >>> Kinoshita <brunodepau...@yahoo.com.br> > > >> >>> > Cc: > > >> >>> > Sent: Tuesday, January 29, 2013 8:57 PM > > >> >>> > Subject: Re: [functor] Change default arity of Function, > > > Predicate > > >> and > > >> >>> Procedure > > >> >>> > > > >> >>> > What about in pure functional languages e.g. Haskell? > > >> >>> > > > >> >>> > Matt > > >> >>> > > > >> >>> > > > >> >>> > On Tue, Jan 29, 2013 at 4:55 PM, Bruno P. Kinoshita < > > >> >>> > brunodepau...@yahoo.com.br> wrote: > > >> >>> > > > >> >>> >> Hi all, > > >> >>> >> > > >> >>> >> In Java 8 and Guava the default arity of a Function > > > is 1, but in > > >> >>> [functor] > > >> >>> >> it is 0, IOW, in Java 8 and Guava a Function is by > > > default a > > >> >>> UnaryFunction, > > >> >>> >> while in [functor] it is a NullaryFunction. > > >> >>> >> > > >> >>> >> What do you guys think of changing the default > > > arity of Function, > > >> >>> >> Procedure and Predicate in [functor] to 1, rather > > > than 0? > > >> >>> >> > > >> >>> >> Cheers > > >> >>> >> > > >> >>> >> Bruno P. Kinoshita > > >> >>> >> http://kinoshita.eti.br > > >> >>> >> http://tupilabs.com > > >> >>> >> > > >> >>> >> > > >> >> > > > --------------------------------------------------------------------- > > >> >>> >> To unsubscribe, e-mail: > > > dev-unsubscr...@commons.apache.org > > >> >>> >> For additional commands, e-mail: > > > dev-h...@commons.apache.org > > >> >>> >> > > >> >>> >> > > >> >>> > > > >> >>> > > >> >> > > >> > > > >> > >--------------------------------------------------------------------- > > >> >To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > > >> >For additional commands, e-mail: dev-h...@commons.apache.org > > >> > > > >> > > > >> > > > >> > > > >> > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > > For additional commands, e-mail: dev-h...@commons.apache.org > > > > > > > -- > http://people.apache.org/~britter/ > http://www.systemoutprintln.de/ > http://twitter.com/BenediktRitter > http://github.com/britter >
