Specs

pop_lazy(map(), key(), (() -> value())) :: {value(), map()}

Lazily returns and removes the value associated with key in map.

If key is present in map, it returns {value, new_map} where value is the value of the key and new_map is the result of removing key from map. If key is not present in map, {fun_result, map} is returned, where fun_result is the result of applying fun.

This is useful if the default value is very expensive to calculate or generally difficult to setup and teardown again.

Examples

iex> map = %{a: 1}
iex> fun = fn ->
...>   # some expensive operation here
...>   13
...> end
iex> Map.pop_lazy(map, :a, fun)
{1, %{}}
iex> Map.pop_lazy(map, :b, fun)
{13, %{a: 1}}