> Why? How Enum.drop/2 is related to Enum.filter/2? They are doing completely different things.
My bad, I was referring to Enum.reject/2! Andrea Leopardi an.leopa...@gmail.com On Sat, Aug 17, 2019 at 11:42 PM Roman Smirnov <pom...@gmail.com> wrote: > Why? How Enum.drop/2 is related to Enum.filter/2? They are doing > completely different things. > > четверг, 15 августа 2019 г., 13:37:07 UTC+3 пользователь Andrea Leopardi > написал: >> >> We should also address the fact that if we add Map.filter/2, we also >> likely have to add Map.drop/2 (to mimic Enum and Stream), but that name is >> already taken. >> >> On Thu, 15 Aug 2019 at 12:26, Johanna Larsson <johanna....@gmail.com> >> wrote: >> >>> The stream version is by far the slowest, which isn't surprising since >>> streams bring some overhead. Didn't measure memory usage though >>> https://gist.github.com/joladev/2b51260107078a1fc7f9d4504916fe21 >>> >>> Honestly, I tend to agree it would be nice to add it, for feature >>> completeness, even if it doesn't improve performance hugely. I understand >>> the desire to avoid unnecessary clutter in the core language, but this is a >>> core erlang function that we're explicitly not wrapping, when most of the >>> other ones are wrapped. And most likely just because it wasn't around from >>> the start. It's quite a bit more ergonomic to use `Map.filter` rather than >>> `for` or `map|>Enum.filter(pred)|>Enum.into({})`. Much cleaner. >>> >>> Not too hard to implement your own version of `Map.filter` though, so I >>> don't feel too strongly about it. >>> >>> On Thu, Aug 15, 2019 at 11:12 AM Alexei Sholik <alcos...@gmail.com> >>> wrote: >>> >>>> The simplest alternative is to use :maps.filter(). It's not as easy to >>>> pipe into, but that's a minor concern for me. >>>> >>>> As another alternative, this should be faster and have lower memory >>>> footprint than using Enum, although you'd need to benchmark it as well to >>>> be sure: >>>> >>>> map >>>> |> Stream.filter(predicate) >>>> |> Map.new() >>>> >>>> Personally, I would love to see an extension for Map.new() that would >>>> allow filtering the first argument in addition to the currently supported >>>> transformation. So instead of the current >>>> >>>> Map.new(enumerable, fn thing -> {key, val} end) >>>> >>>> we could have >>>> >>>> Map.new(enumerable, map: fn thing -> {key, val} end, filter: fn {_key, >>>> val} -> predicate(val) end) >>>> >>>> Such an extension is unlikely to be added though because it would be >>>> another way of doing what is already possible with Enum, Stream, and Map. >>>> >>>> On Thu, Aug 15, 2019 at 10:29 AM Roman Smirnov <pom...@gmail.com> >>>> wrote: >>>> >>>>> Since OTP 18 there is a pretty convenient function :maps.filter >>>>> <http://erlang.org/doc/man/maps.html#filter-2>. >>>>> >>>>> I think it would be nice to have Map.filter(map, predicate) in Elixir >>>>> as well instead of doing >>>>> >>>>> >>>>> map|> Enum.filter(predicate)|> Enum.into(%{}) >>>>> >>>>> >>>>> or >>>>> >>>>> for {key, value} <- map, some_filter(key, value), into: %{}, do: {key, >>>>> value} >>>>> >>>>> The first one alternative is slower, b/c of 2-step transformation, and >>>>> the second one consume more memory, could not be piped and has a lack >>>>> of expressiveness (too imperative way to do a simple filtration). >>>>> There were benchmarks and a small discussion in PR: >>>>> https://github.com/elixir-lang/elixir/pull/9292, but the discussion >>>>> should be moved to this mailing list. >>>>> >>>>> >>>>> -- >>>>> 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-l...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/elixir-lang-core/5d403c4a-91f8-4c4d-8dc0-297185a2aed8%40googlegroups.com >>>>> <https://groups.google.com/d/msgid/elixir-lang-core/5d403c4a-91f8-4c4d-8dc0-297185a2aed8%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-l...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/elixir-lang-core/CAAPY6eO5aDifRxHxv7QtD4%3Di_bYbUw1sphxMhq4jEjuR9naPSQ%40mail.gmail.com >>>> <https://groups.google.com/d/msgid/elixir-lang-core/CAAPY6eO5aDifRxHxv7QtD4%3Di_bYbUw1sphxMhq4jEjuR9naPSQ%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-l...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/elixir-lang-core/CAKL9qdTxQWdKDM7B%3D1XLkf7w9PeshpfSyrpsuhM%3DeaEqdZVSDA%40mail.gmail.com >>> <https://groups.google.com/d/msgid/elixir-lang-core/CAKL9qdTxQWdKDM7B%3D1XLkf7w9PeshpfSyrpsuhM%3DeaEqdZVSDA%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> >> Andrea Leopardi >> an.le...@gmail.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-core+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elixir-lang-core/c819a8cc-c3b6-41cc-a056-76a294b79fb6%40googlegroups.com > <https://groups.google.com/d/msgid/elixir-lang-core/c819a8cc-c3b6-41cc-a056-76a294b79fb6%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. 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