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From Matt Benson <gudnabr...@gmail.com>
Subject Re: [functor] Change default arity of Function, Predicate and Procedure
Date Thu, 14 Feb 2013 15:51:48 GMT
I would say that certainly one would often want to create an API like
you've described.  What I am reluctant not to support is:

class Foo {
  static void add(Argumented<Binary<? extends CharSequence, ? extends
CharSequence>> functor);
}

Foo.add(new BinaryFunction<String, String, String>() {});
Foo.add(new BinaryProcedure<String, StringBuffer>() {});
Foo.add(new BinaryPredicate<String, StringBuilder>() {});

The arguments are alike in their "argumentedness" while having different
functional interfaces.  Convince me this can never be useful, and we can
drop the whole thing ;P

Matt


On Thu, Feb 14, 2013 at 8:55 AM, Jörg Schaible
<Joerg.Schaible@scalaris.com>wrote:

> Hi Matt,
>
> Matt Benson wrote:
>
> > Once again, an enum wouldn't readily be able to contribute to your
> > functor's being able to participate in some method by type signature;
> > i.e., I want to support the use case of:
> >
> > add(Argumented<Binary> somethingThatTakesTwoArguments);
> >
> > Maybe this isn't a worthwhile goal, but so far I don't see anything else
> > that accomplishes this.
>
> In any case, I wonder if we really want to support type safety for the
> argument *types* themselves.
>
> [snip]
>
> >> >>>
> >> >>> interface Arity {
> >> >>> }
> >> >>>
> >> >>> interface Argumented<A extends Arity> {
> >> >>> }
> >> >>>
> >> >>> interface Unary<A> extends Arity {
> >> >>> }
> >> >>>
> >> >>> interface UnaryFunction<A, T> extends Argumented<Unary<A>>
{
> >> >>> }
> >> >>>
> >> >>>
> >> >> This is more complicated then having the functors extend Arity, but
> it
> >> >> makes better use of inheritance from an OO POV I think.
> >> >>
> >> >> Just to make sure I understand correctly: If I had an UnaryFunction
> >> >> that take a Boolean argument and return an Integer I would model this
> >> >> as: class MyFunction implements UnaryFunction<Boolean, Integer>,
> >> >> right?
>
>  class Foo {
>  static CharSequence add(UnaryFunction<? extends CharSequence, ? extends
> CharSequence> f);
>  }
>
>  Foo.add(new UnaryFunction<String, String>(){});
>  Foo.add(new UnaryFunction<StringBuilder, String>(){});
>  Foo.add(new UnaryFunction<StringBuilder, StringBuilder>(){});
>
>
> This could get really nasty to use.
>
> - Jörg
>
>
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