Map.get_lazy
You're seeing just the function
get_lazy
, go back to Map module for more information.
Specs
Gets the value for a specific key
in map
.
If key
is present in map
then its value value
is
returned. Otherwise, fun
is evaluated and its result is returned.
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.get_lazy(map, :a, fun)
1
iex> Map.get_lazy(map, :b, fun)
13