[Proposal] Enum.max/2, Enum.min/2, Enum.min_max/2

[Myron Marston]

When using Enum’s min/max/min_max functions, I frequently have to provide special case logic to deal with an empty collection, such as this:

def date_range_from(all_time_slices) do
  case all_time_slices do
    [] -> {nil, nil}
    [_ | _] -> Enum.min_max(all_time_slices)
  end
end

It would be nice if there was a 2-arity version of these functions that you could pass to determine what to do with an empty collection. For this case, I’m imagining:

def date_range_from(all_time_slices) do
  Enum.min_max(all_time_slices, {nil, nil})
end

This aligns with functions like Map.get/3 that allow you to pass a default. Alternately, I could see an argument for requiring the 2nd argument to be a function:

def date_range_from(all_time_slices) do
  Enum.min_max(all_time_slices, fn -> {nil, nil} end)
end

Then the 1-arity version of these functions could just call the 2-arity version with a function that raises an Enum.EmptyError. That said, I think I prefer the version that allows you to pass a default return value w/ no need to wrap it in a function.

Thoughts?
Myron

​

[José Valim]

I am +1 for the function based function because we can argue that the default function raises Enum.EmptyError. So we keep backwards compatibility and get a feature out of it. :)

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D

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[José Valim]

Btw, if you don't have time to send a PR, please open up an issue and someone will certainly grab it. :)

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D

[Myron Marston]

Thanks, José.  I plan to open a PR soon.

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