It is ambiguous in the sense it now requires context. when I see &2, I will no longer know what it means without also analyzing its surrounding context. It means that every time I scan &2 in a line, I need to think which one of its two uses is being applied.
On Fri, Aug 23, 2024 at 23:53 Ivan Yurov <ivan.your...@gmail.com> wrote: > I agree it's controversial, but it's certainly not too short: here's the > example of how Scala does it > https://docs.scala-lang.org/scala3/book/fun-anonymous-functions.html, if > I remember correctly Haskell has something like that as well, but it might > be powered by currying, so not exactly related to lambda notation. > > Can you give some examples of where it could be ambiguous, please? I agree > that declaring arity explicitly along the introductory & might be > cumbersome (yet if it's optional, then no harm to existing code is done), > but how about zero argument lambdas? I understand that &1 would be > ambiguous, but &(1) wouldn't. Or am I missing something? Perhaps other > special uses of &? > > On Thu, Aug 22, 2024 at 11:16 PM José Valim <jose.va...@dashbit.co> wrote: > >> Thank you for the proposal. >> >> Some would already say the capture syntax is already too concise (and >> they would always prefer fn instead), and the proposal would introduce >> ambiguity to them, given that &2 would have different meanings depending on >> where it is located. One of the big rules in Elixir is that, when we give >> syntax affordances, such as the capture operator, we keep its usage rules >> clear and this extension would violate that (in my opinion). >> >> On Fri, Aug 23, 2024 at 8:06 AM Ivan Yurov <ivan.your...@gmail.com> >> wrote: >> >>> The lambdas I want to be able to create using short notation are in the >>> second block of code in the original posting. They are slightly less >>> obvious than & &1 + 1. >>> As far as I understand, there's no way to compose them using short form, >>> unless I'm missing something. The idea to supply a number of arguments >>> along with introductory & is probably not gonna fly — it would look too >>> similar to argument itself, although there shouldn't be any ambiguity with >>> parsing since nested short form lambdas are not allowed anyways. Maybe &/2 >>> which would be consistent with captures? >>> >>> >>> On Thu, Aug 22, 2024 at 10:19 AM Ben Wilson <benwilson...@gmail.com> >>> wrote: >>> >>>> Hey Ivan, >>>> >>>> You're just missing the introductory & >>>> >>>> iex(1)> & &1 + 1 >>>> #Function<42.105768164/1 in :erl_eval.expr/6> >>>> >>>> On Wednesday, August 21, 2024 at 2:03:24 AM UTC-4 ivan.y...@gmail.com >>>> wrote: >>>> >>>>> I realize it might be controversial, but I truly enjoy short form >>>>> lambdas in any language I touch and Elixir is one of them. Yet I think >>>>> there's a couple of use cases that are uncovered. One is when you need to >>>>> encode a zero argument lambda returning a value and the second one is when >>>>> there are more arguments than actually used: >>>>> >>>>> iex(1)> &(&2 + 1) >>>>> >>>>> error: capture argument &2 cannot be defined without &1 (you cannot >>>>> skip arguments, all arguments must be numbered) >>>>> >>>>> └─ iex:1 >>>>> >>>>> >>>>> ** (CompileError) cannot compile code (errors have been logged) >>>>> >>>>> >>>>> iex(1)> &(1) >>>>> >>>>> error: capture argument &1 must be used within the capture operator & >>>>> >>>>> └─ iex:1 >>>>> >>>>> >>>>> ** (CompileError) cannot compile code (errors have been logged) >>>>> >>>>> I think both of these cases would be handled if we let explicitly >>>>> defining the arity of lambda: &2(&2 + 1) or something like that. Since >>>>> nested lambdas are not allowed anyways, this should work (unless I'm >>>>> missing something). And we'd assume if there's no access to the variables, >>>>> it would be a zero argument function, so &(1) would work too. >>>>> >>>>> This should be fundamentally possible, since I can do this: >>>>> >>>>> iex(9)> fn () -> :ok end >>>>> >>>>> #Function<43.105768164/0 in :erl_eval.expr/6> >>>>> >>>>> iex(10)> fn (_a, b) -> b * 2 end >>>>> >>>>> #Function<41.105768164/2 in :erl_eval.expr/6> >>>>> >>>>> So I assume it boils down to parsing? Either way, I'd love to see that >>>>> in Elixir and I'm willing to contribute some time to get it implemented if >>>>> the community approves it. >>>>> >>>> -- >>>> You received this message because you are subscribed to a topic in the >>>> Google Groups "elixir-lang-core" group. >>>> To unsubscribe from this topic, visit >>>> https://groups.google.com/d/topic/elixir-lang-core/g2tQI1FjcNU/unsubscribe >>>> . >>>> To unsubscribe from this group and all its topics, send an email to >>>> elixir-lang-core+unsubscr...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/elixir-lang-core/11ca2681-4b0e-4875-ac48-455a5e684f6en%40googlegroups.com >>>> <https://groups.google.com/d/msgid/elixir-lang-core/11ca2681-4b0e-4875-ac48-455a5e684f6en%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> >>> >>> -- >>> Kind regards, >>> Ivan Yurov >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "elixir-lang-core" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to elixir-lang-core+unsubscr...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/elixir-lang-core/CAAoaZy4gPokWC7urFA7sjqHzL%3DyVKdkHqGd6PM_Sc5o0MDtVGg%40mail.gmail.com >>> <https://groups.google.com/d/msgid/elixir-lang-core/CAAoaZy4gPokWC7urFA7sjqHzL%3DyVKdkHqGd6PM_Sc5o0MDtVGg%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to a topic in the >> Google Groups "elixir-lang-core" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/elixir-lang-core/g2tQI1FjcNU/unsubscribe >> . >> To unsubscribe from this group and all its topics, send an email to >> elixir-lang-core+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4K9SLYYFOU0dPAQ0uqAc7ms4Dq%2B8gPfX4Y0zY9uHJ4Frg%40mail.gmail.com >> <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4K9SLYYFOU0dPAQ0uqAc7ms4Dq%2B8gPfX4Y0zY9uHJ4Frg%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . > > >> > > -- > Kind regards, > Ivan Yurov > > -- > You received this message because you are subscribed to the Google Groups > "elixir-lang-core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to elixir-lang-core+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elixir-lang-core/CAAoaZy7-w%2BvyWY9t6v03wrfyMfc4XKy1UyEs0K7AtEedEGt5sQ%40mail.gmail.com > <https://groups.google.com/d/msgid/elixir-lang-core/CAAoaZy7-w%2BvyWY9t6v03wrfyMfc4XKy1UyEs0K7AtEedEGt5sQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-core+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4KBLEF9umPV9dQpeQEgFnOoTGmXo%3DM0MfaTFfO4eg-54Q%40mail.gmail.com.
