TL;DR - pull request is welcome.
My initial take was that the performance benefits are not significant but
then, after carefully checking the Enum API, I realized that my
slippery-slope argument does not hold: there aren't any other functions, as
far as I can tell, that would make sense to be
Of course some numbers would be great to look at here - here is a benchmark
for an implementation of Map.split_with/2 comparing the results agains a
few implementations using the current standard library
Code
```elixir
defmodule SplitWith do
def test do
map = Map.new(0..1000, fn n -> {n,
