🤩 Better defaults with Enum.find/3
Notes
You’re familiar with Enum.find/2. It returns the value for which the fun is
true:
Enum.find([1, 2, 3, 4], fn i -> i == 3 end)
# => 3
But when a value can’t be found, it returns nil.
Enum.find([1, 2, 3, 4], fn i -> i == 5 end)
# => nil
Of course, that’s not always desirable, since nil values have a way of
propagating through our systems. 😞
So, sometimes it’s nicer to have a more clear value returned when nothing is found:
Enum.find([1, 2, 3, 4], :not_found, fn i -> i == 3 end)
# => :not_found
That’s much better!
And that’s especially helpful if Enum.find/3 is just an implementation detail
of a larger function in your domain:
@spec get_user(String.t()) :: User.t() | :not_found
def get_user(id) do
all_users()
|> Enum.find(:not_found, fn user ->
user.id == id
end)
end