I would benchmark to make sure that you're actually gaining something. If you are relying on it to be small, then at that specific size a list might also just be fine, and you won't be relying on behavior that could change in a future release.
On Monday, March 7, 2022 at 11:49:06 AM UTC-5 Max Veytsman wrote: > For what it's worth, I use MapSets for these kinds of autocompletion > suggestion lists in LiveView. It's worth noting that these aren't > guaranteed to preserve insertion order, and I'm relying on a implementation > detail that they will for a small number of keys. > > On Mon, Mar 7, 2022 at 10:51 AM h...@nathanmlong.com <h...@nathanmlong.com> > wrote: > >> Hmm. I can't give too much detail, but the basic context is a LiveView >> form where the user selects some ports and the form provides suggestions as >> they type. Eg, if they type `2` it will suggest `22 - SSH`, `25 - SMTP`, >> etc. >> >> The currently-selected ports are a list of integers. If `22` is already >> selected, the LiveView won't suggest it. So if the LiveView gets a message >> to deselect `22`, it tries to pop it out of the `selections` list. If the >> pop succeeds, the `suggestions` list can be updated to include port `22` >> again. If the pop doesn't succeed, we can ignore the message; we can't >> deselect a port that wasn't selected to start with. >> >> I can't combine `selected` and `suggested` (eg by flagging the >> suggestions which are also selected) because both collections can contain >> elements that the other doesn't contain; the user may select ports that are >> not in the suggestions list. And it's not practical to have a top-level >> list of every possible port and flag each as `selected`, `suggested`, or >> both, because there are are 65,535 possible ports. >> >> So the core of my use case is: I get a user message to remove an item >> from a list, and after attempting to remove it, I want to take a follow-up >> action only if the item was was actually in the list. >> >> On Friday, March 4, 2022 at 11:05:35 AM UTC-5 José Valim wrote: >> >>> Hi Nathan, thanks for the email. Can you please show some examples of >>> where they could be handy with some context around them? Thank you! >>> >>> On Fri, Mar 4, 2022 at 3:45 PM h...@nathanmlong.com < >>> h...@nathanmlong.com> wrote: >>> >>>> This is a modified version of what I proposed in >>>> https://github.com/elixir-lang/elixir/pull/11681 >>>> >>>> Similar to `Map.pop/2` and and `Keyword.pop/2`, I propose adding >>>> `List.pop/2`. >>>> >>>> I also propose adding `List.find_and_pop/2`, which is more generalized >>>> since it takes a function. >>>> >>>> Here are possible implementations. >>>> >>>> ```elixir >>>> @doc """ >>>> Returns and removes the first value matching `item` in the `list`. >>>> >>>> ## Examples >>>> iex> List.pop([1, 2, 2, 3], 2) >>>> {2, [1, 2, 3]} >>>> iex> List.pop([1, 2, 3, 4], 20) >>>> {nil, [1, 2, 3, 4]} >>>> """ >>>> def pop(list, item) do >>>> find_and_pop(list, &(&1 == item)) >>>> end >>>> >>>> @doc """ >>>> Returns and removes the first value matching `fun` in the `list`. >>>> >>>> ## Examples >>>> iex> List.find_and_pop([1, 2, 3, 4], &(&1 > 2)) >>>> {3, [1, 2, 4]} >>>> iex> List.find_and_pop([1, 2, 3, 4], &(&1 > 20)) >>>> {nil, [1, 2, 3, 4]} >>>> """ >>>> def find_and_pop(list, fun) do >>>> case Enum.find_index(list, fun) do >>>> nil -> {nil, list} >>>> i -> pop_at(list, i) >>>> end >>>> end >>>> ``` >>>> >>>> -- >>>> 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/bdc98b8c-fc73-40d7-8287-eb0b5d3ea97en%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/elixir-lang-core/bdc98b8c-fc73-40d7-8287-eb0b5d3ea97en%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/57bc38e4-2596-415c-8dbf-a235330d459an%40googlegroups.com >> >> <https://groups.google.com/d/msgid/elixir-lang-core/57bc38e4-2596-415c-8dbf-a235330d459an%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/fa78cd65-804d-4160-99fb-58d0e0994ddan%40googlegroups.com.
