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-core+unsubscr...@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/CAD8aQuLR0xs7Od3Vs9_z7a6FM6TbC4yS72Oc2s2jw7VJ4rhYbA%40mail.gmail.com.
