[erlang-questions] optimal way to append an element in a list inside a map

Caragea Silviu <>
Tue Aug 29 19:34:33 CEST 2017


Hello,

Having a map where the value of each element it's a list :

#{ 1 => [], 2 => [], ... n => []}

and you need to append elements in the list for a specific key, what's the
most optimal way to do this without copying the lists and the map inside
the VM lot of times ?

Anything better than the following solution:

append_element(Key, Value, Map) ->
    case maps:find(Key, Map) of
        {ok, V} ->
            maps:put(Key, [Value | V], Map);
        _ ->
            maps:put(Key, [Value], Map)
    end.

Kind regards,
Silviu
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