Ah (replying to both Brandon and JJ since their replies crossed): So `--> Mu` is not a sufficient and/or correct return constraint for things like AT-POS because why, then? On Thu, Oct 4, 2018 at 14:56 Brandon Allbery <allber...@gmail.com> wrote:
> I think they meant more like my AT-POS example: the point is the return > value, but you can't say ahead of time what type it will have. > > On Thu, Oct 4, 2018 at 2:48 PM Trey Harris <t...@lopsa.org> wrote: > >> >> >> On Thu, Oct 4, 2018 at 02:13 JJ Merelo <jjmer...@gmail.com> wrote: >> >>> >>> >>> El jue., 4 oct. 2018 a las 3:36, Trey Harris (<t...@lopsa.org>) >>> escribió: >>> >>>> _All_ routines in Perl 6 return _something._ A lack of a "-->" simply >>>> indicates stylistically that the return is not useful because it's whatever >>>> "falls off the end". (There's a bit of variance here as I'm not sure it's a >>>> convention everyone has followed.) It's equivalent to "--> Mu" because >>>> anything that could "fall of the end" is Mu. >>>> >>> >>> No, it means that it's not constrained to a type. It can still return >>> something, but it can be anything. >>> >> >> >> I get all that, except for the "No" at the front. ;-) >> >> Or were you talking about the "not useful" bit? Yes, of course in any >> given codebase, the lack of a return value has no more or less meaning than >> a lack of any constraint. The programmer may not like using constraints at >> all and treats Perl 6 like Perl 5 in the respect of wanting arbitrarily >> mungible values. >> >> But the word "stylistically" was important, as I was responding to Todd's >> question about the docs—I think a lack of a return value in the docs (at >> least, the ones I could come up with in a grep pattern on my checkout of >> docs) does tend to indicate that the return is not useful, that the routine >> is a "procedure" run for its side effects rather than for evaluation. >> >> Is that what you meant? >> >> If you were saying in "it can still return something, but can be >> anything", that "anything ⊃ (is a strict superset of) `Mu`", then I >> don't understand, because I thought all values conformed to Mu. >> >> > > -- > brandon s allbery kf8nh > allber...@gmail.com >
