Why not make it a filter that applies it to all matching?
On Thursday, July 28, 2016, Michał Muskała <[email protected]> wrote:
> Hello everybody,
>
> I’d like to propose adding a new accessor function to Access -
> Access.find/1. It works exactly like Access.at/1, but instead of accessing
> an element by index (with Enum.at/1), you can provide an arbitrary function
> that will be used with Enum.find/2 to match the proper value.
> I implemented this function in a project, since I needed it. Maybe it
> would be generally useful? The implementation is rather simple:
>
> def find(fun) when is_function(fun, 1) do
> fn(op, data, next) -> find(op, data, fun, next) end
> end
>
> defp find(:get, data, fun, next) when is_list(data) do
> data |> Enum.find(fun) |> next.()
> end
>
> defp find(:get_and_update, data, fun, next) when is_list(data) do
> case Enum.split_while(data, &(not fun.(&1))) do
> {preceding, []} ->
> {nil, preceding}
> {preceding, [elem | following]} ->
> case next.(elem) do
> {get, update} -> {get, preceding ++ [update] ++ following}
> :pop -> {elem, preceding ++ following}
> end
> end
> end
>
> defp find(_op, data, _fun, _next) do
> raise "Access.find/1 expected a list, got: #{inspect data}"
> end
>
> Michał.
>
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