What about count_upto or count_up_to This is similar to the ruby method .upto.
On Fri, 4 Dec 2020 at 16:20, Zachary Daniel <zachary.s.dan...@gmail.com> wrote: > `count_while` would imply (to me) that it counts while a predicate returns > true. The only name I can think of that would be expressive and consistent > with other Enum functions would be something like `Enum.count_take` or > `Enum.take_count`, but I think that `Enum.take_until` is a better name. > > On Friday, December 4, 2020 at 10:50:18 AM UTC-5 mario.luis...@gmail.com > wrote: > >> This would be the first function in Enum with "until" in its name. For >> consistency with the other functions in this module, wouldn't it be >> preferable the "while" suffix instead ? >> >> A sexta-feira, 4 de dezembro de 2020 à(s) 07:29:29 UTC, José Valim >> escreveu: >> >>> We can also add Enum.count_until(enumerable, filter, n) and you can use >>> filter = & &1 if you want to force enumeration, like there is for >>> Enum.count/2 today. >>> >>> On Fri, Dec 4, 2020 at 8:28 AM José Valim <jose....@dashbit.co> wrote: >>> >>>> That's a very good point Jayson. I think we should go with "count until >>>> should take advantage of all optimizations and ignore side-effects”. I >>>> believe it is fair to expect that no enumerable that implements count >>>> actually has side-effects, exactly because of the implications of what you >>>> said. >>>> >>>> On Fri, Dec 4, 2020 at 8:08 AM 'Jayson Vantuyl' via elixir-lang-core < >>>> elixir-l...@googlegroups.com> wrote: >>>> >>>>> There are three questions I don’t think we’re considering: >>>>> * What does it mean to “partially count” an Enumerable that implements >>>>> an “efficient” `count/1` function? >>>>> * If such an Enumerable has side-effects for its `reduce/3` function, >>>>> should they be somehow still happen even though the `count/1` doesn’t >>>>> necessarily iterate the elements? >>>>> * If such an Enumerable returns a larger count that asked for, should >>>>> we return the larger “technically correct” value; or the `max + 1` value? >>>>> >>>>> I generally like `count_until/2` because it‘s unopinionated about what >>>>> you’re doing with the count. But the answers to the above question >>>>> probably >>>>> should be addressed and documented. >>>>> >>>>> I really see two ways to address the above question. Either we >>>>> consider “count until implies actively counting” or “count until should >>>>> take advantage of all optimizations and ignore side-effects”. >>>>> >>>>> My feel is that the latter is generally going to be more efficient in >>>>> the common case but the former is less likely to create unexpected >>>>> behavior >>>>> from people who don’t know how their Enumerable is implemented. >>>>> >>>>> I’m inclined to favor the former. It won’t throw away efficiency that >>>>> a custom Enumerable will implement, it’ll generally make naive code >>>>> faster, >>>>> and the rare cases where people expect side-effects is probably less >>>>> important than either of those other benefits. >>>>> >>>>> Sent from my iPhone >>>>> >>>>> On Dec 3, 2020, at 21:18, José Valim <jose....@dashbit.co> wrote: >>>>> >>>>> >>>>> Thanks Allen! I believe that's a good idea. >>>>> >>>>> I think the main insight is that we don't want a predicate function >>>>> (at_least? more_than?). Using compare returns three states - which is >>>>> better than two - but what if we just returned the number? After all, if I >>>>> am interested in knowing if something has less than 10, 10, or more than >>>>> 10, I just need to count until eleven. Returning a number seems to be more >>>>> flexible too. Therefore, what do you think about: count_until(enum, >>>>> value)? >>>>> >>>>> To check if less, eq, or more than 10: >>>>> >>>>> case Enum.count_until(count, 10 + 1) do >>>>> 11 -> :gt >>>>> 10 -> :eq >>>>> _ -> :lt >>>>> end >>>>> >>>>> For at least 10: >>>>> >>>>> Enum.count_until(count, 10) == 10 >>>>> >>>>> For more than 10: >>>>> >>>>> Enum.count_until(count, 10 + 1) > 10 >>>>> >>>>> Thoughts? >>>>> >>>>> >>>>> On Fri, Dec 4, 2020 at 2:14 AM Zach Daniel <zachary....@gmail.com> >>>>> wrote: >>>>> >>>>>> Yep! I really like it :) >>>>>> >>>>>> On Thu, Dec 3, 2020 at 7:52 PM eksperimental <eksper...@autistici.org> >>>>>> wrote: >>>>>> >>>>>>> On Thu, 3 Dec 2020 19:06:18 -0500 >>>>>>> Allen Madsen <allen.c...@gmail.com> wrote: >>>>>>> >>>>>>> > Enum.compare_count([], 1) #=> :lt >>>>>>> > Enum.compare_count([1], 1) #=> :eq >>>>>>> > Enum.compare_count([1, 2], 1) #=> :gt >>>>>>> >>>>>>> This is the way to go, because in one function call we can determine >>>>>>> the >>>>>>> course of the action, such as in >>>>>>> >>>>>>> case Enum.compare_count(list, n) do >>>>>>> :lt -> ... >>>>>>> :eq -> ... >>>>>>> :gt -> ... >>>>>>> end >>>>>>> >>>>>>> when using the predicate functions it would require at least two >>>>>>> function calls. >>>>>>> >>>>>>> > >>>>>>> > Allen Madsen >>>>>>> > http://www.allenmadsen.com >>>>>>> > >>>>>>> > >>>>>>> > On Thu, Dec 3, 2020 at 6:51 PM Zach Daniel >>>>>>> > <zachary....@gmail.com> wrote: >>>>>>> > >>>>>>> > > Well, List.count doesn’t exist yet, but either way it sounds like >>>>>>> > > not a great idea :) I couldn’t find examples in other Lang’s, so >>>>>>> > > maybe I’ll just throw out some other names: >>>>>>> > > >>>>>>> > > Enum.at_least?/2 >>>>>>> > > >>>>>>> > > Enum.at_most?/2 >>>>>>> > > >>>>>>> > > Enum.has_count?/2 >>>>>>> > > >>>>>>> > > On Thu, Dec 3, 2020 at 5:14 PM Michał Muskała <mic...@muskala.eu >>>>>>> > >>>>>>> > > wrote: >>>>>>> > > >>>>>>> > >> Unfortunately this can’t be done automatically since it has >>>>>>> subtle >>>>>>> > >> semantic differences. In particular Enum.count/1 (or length/1) >>>>>>> not >>>>>>> > >> only traverses the list to count its size, but also verifies >>>>>>> it’s >>>>>>> > >> a proper list raising an exception for improper lists. The >>>>>>> > >> difference could be seen for value like: >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> [1, 2, 3 | :invalid] >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> Calling length/1 or Enum.count/1 on this raises. If compiler did >>>>>>> > >> the optimisation you propose, for something like length(list) > >>>>>>> 0, >>>>>>> > >> it wouldn’t fully traverse the list and wouldn’t raise. Thus >>>>>>> such >>>>>>> > >> an optimisation is not possible in the general case. >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> *From: *elixir-l...@googlegroups.com < >>>>>>> > >> elixir-l...@googlegroups.com> >>>>>>> > >> *Date: *Thursday, 3 December 2020 at 22:04 >>>>>>> > >> *To: *elixir-l...@googlegroups.com < >>>>>>> > >> elixir-l...@googlegroups.com> >>>>>>> > >> *Subject: *Re: [elixir-core:9802] Proposal `Enum.more_than?/2` >>>>>>> or >>>>>>> > >> `List.more_than?/2` >>>>>>> > >> >>>>>>> > >> This probably off the table/unreasonable, but it also seems like >>>>>>> > >> something that could be statically solved and people would never >>>>>>> > >> need to know as it is just an optimization. E.g >>>>>>> Enum.count(list) > >>>>>>> > >> n could optimized by the compiler? Probably wouldn’t be good for >>>>>>> > >> all Enums, since counting would be expected to enumerate them, >>>>>>> so >>>>>>> > >> maybe only something like List.count 🤷♂️ >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> On Thu, Dec 3, 2020 at 1:42 PM Zach Daniel >>>>>>> > >> <zachary....@gmail.com> wrote: >>>>>>> > >> >>>>>>> > >> Another benefit to the options list would be supporting it for >>>>>>> > >> count with a predicate, e.g Enum.count(enum, &some_predicate/1, >>>>>>> > >> max: 4) >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> On Thu, Dec 3, 2020 at 1:35 PM Zach Daniel >>>>>>> > >> <zachary....@gmail.com> wrote: >>>>>>> > >> >>>>>>> > >> Nothing is jumping out at me from elsewhere yet, but another >>>>>>> > >> option might be accepting options in `Enum.count`, like >>>>>>> > >> `Enum.count(list, max: 4)`. I’ll keep searching though. >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> On Thu, Dec 3, 2020 at 1:31 PM Zach Daniel >>>>>>> > >> <zachary....@gmail.com> wrote: >>>>>>> > >> >>>>>>> > >> I agree on the name feeling subpar :) I’ll take a look and see >>>>>>> if >>>>>>> > >> I can find other examples. >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> On Thu, Dec 3, 2020 at 12:21 PM José Valim <jose....@dashbit.co >>>>>>> > >>>>>>> > >> wrote: >>>>>>> > >> >>>>>>> > >> Thanks Zach! I like this idea but the proposed name, for some >>>>>>> > >> reason, doesn't sit right with me. Is there any prior art from >>>>>>> > >> other langs we could look at? >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> On Thu, Dec 3, 2020 at 6:15 PM Zachary Daniel >>>>>>> > >> <zachary....@gmail.com> wrote: >>>>>>> > >> >>>>>>> > >> Counting a list, especially a large one, to know if there are >>>>>>> > >> "more than x" or "less than x" items is inefficient. >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> Right now I often see things like `if Enum.count(list) > 4 ...`, >>>>>>> > >> mostly because writing a recursive `more_than?` check is >>>>>>> tedious, >>>>>>> > >> or doing something like `Enum.empty?(Enum.drop(list, 4))` is not >>>>>>> > >> very expressive. >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> >>>>>>> > >> I think it would be nice to have an `Enum.more_than?` that does >>>>>>> > >> that work for you. It could also be `List.more_than?/2` if we >>>>>>> > >> don't want it in Enum. Any thoughts? >>>>>>> > >> >>>>>>> > >> -- >>>>>>> > >> 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-co...@googlegroups.com. >>>>>>> > >> To view this discussion on the web visit >>>>>>> > >> >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/263d7c39-a32b-4294-93d8-40f248c9b3c8n%40googlegroups.com >>>>>>> > >> < >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/263d7c39-a32b-4294-93d8-40f248c9b3c8n%40googlegroups.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-co...@googlegroups.com. >>>>>>> > >> To view this discussion on the web visit >>>>>>> > >> >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4JX4NE1yWH1G5L_DjF18v8zejF0%2BSkb_oz%3DPiUHM8Mz1w%40mail.gmail.com >>>>>>> > >> < >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4JX4NE1yWH1G5L_DjF18v8zejF0%2BSkb_oz%3DPiUHM8Mz1w%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-co...@googlegroups.com. >>>>>>> > >> >>>>>>> > >> To view this discussion on the web visit >>>>>>> > >> >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAK-yb0BBGCrgbZamFs%2BeqLUis6mFQgvUHkKK1htSN5rDDWwMRQ%40mail.gmail.com >>>>>>> > >> < >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAK-yb0BBGCrgbZamFs%2BeqLUis6mFQgvUHkKK1htSN5rDDWwMRQ%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-co...@googlegroups.com. >>>>>>> > >> To view this discussion on the web visit >>>>>>> > >> >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/DB7PR07MB3899C92933992464F17898E1FAF20%40DB7PR07MB3899.eurprd07.prod.outlook.com >>>>>>> > >> < >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/DB7PR07MB3899C92933992464F17898E1FAF20%40DB7PR07MB3899.eurprd07.prod.outlook.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-co...@googlegroups.com. >>>>>>> > > To view this discussion on the web visit >>>>>>> > > >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAK-yb0BO2QESHcaL7-svOoAGqvr6hJi%3D8AHFqi-qNZdoFEMMwA%40mail.gmail.com >>>>>>> > > < >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAK-yb0BO2QESHcaL7-svOoAGqvr6hJi%3D8AHFqi-qNZdoFEMMwA%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-co...@googlegroups.com. >>>>>>> To view this discussion on the web visit >>>>>>> https://groups.google.com/d/msgid/elixir-lang-core/5fc98859.1c69fb81.3cf33.11a4SMTPIN_ADDED_MISSING%40gmr-mx.google.com >>>>>>> . >>>>>>> >>>>>> -- >>>>>> 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-co...@googlegroups.com. >>>>>> To view this discussion on the web visit >>>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAK-yb0AfjLS-vef8u9EWpuQ3tHVaXXfvAF9QMu%2B9hin7WjoNQA%40mail.gmail.com >>>>>> <https://groups.google.com/d/msgid/elixir-lang-core/CAK-yb0AfjLS-vef8u9EWpuQ3tHVaXXfvAF9QMu%2B9hin7WjoNQA%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-co...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4LNUYuR%2BztiJ5p3viSEd-Tj6CbptUvyt9CrGigRtKjTMQ%40mail.gmail.com >>>>> <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4LNUYuR%2BztiJ5p3viSEd-Tj6CbptUvyt9CrGigRtKjTMQ%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-co...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/elixir-lang-core/1B141347-7013-4C56-BCFB-E1A1A4430422%40brex.com >>>>> <https://groups.google.com/d/msgid/elixir-lang-core/1B141347-7013-4C56-BCFB-E1A1A4430422%40brex.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/9938fb50-2325-4239-b3f6-7aa66a236d9dn%40googlegroups.com > <https://groups.google.com/d/msgid/elixir-lang-core/9938fb50-2325-4239-b3f6-7aa66a236d9dn%40googlegroups.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/CADwgC_B%2BO%2BKv8PYunamYuxqpKShKE3_%2BXaEbAPDV-qu6q_u3og%40mail.gmail.com.
