Another advantage it is the support of dynamic key pattern matching.
If you are supporting function which accept paramete as the keys to filter
the map, so it can be dynamically filtered out.
Example
def get_data(fields) do
get_map_from_state_or_db()
|> Map.take_in(fields) # or take_in (with Access implementation)
end
Le mercredi 2 septembre 2020 à 14:30:36 UTC+2, Samuel Manzanera a écrit :
>
> Hello everybody,
>
> I propose the support of Map.take_in/2 to extract values using nested keys
> (recursively).
>
> I think it may be useful when you only want a part of the map -- mostly
> when its deep nested map (i.e KV stores, DB engines, etc..) to reduce
> memory footprint with copy and message passing.
>
> Example:
>
>
> iex> Map.take_in(%{a: "hello", b: %{c: "hi", d: "hola"}}, [:a, b: [:d]])
>
> %{a: "hello", b: %{d: "hola"}}
>
> As discussed in the #1029
> <https://github.com/elixir-lang/elixir/pull/10296> the feature should be
> extended to Access for both Map and Keyword implementation.
>
> To analyse the efficiency regarding pattern matching.
>
> But it's a way to resolve the duplication from pattern matching as in this
> example.
>
> iex> %{a: a, b: %{d: d}} = %{a: "hello", b: %{c: "hi", d: "hola"}}
> iex> %{a: a, b: %{d: d}}
> %{a: "hello", b: %{d: "hola"}}
>
>
> Thanks :)
>
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