Proposal: Addition of `either` and `both` operators

[Daniel Angell]

As an alternative to:

if foo(my_baz) and bar(my_baz) do

  # ...
end

it would be great to have `either` and `both` operators as sugar

if my_baz both foo and bar do

  # ...

end

if my_baz either foo or bar do

  # ...

end

These operators could be equivalent to the following function definitions

def both(_, true, true),      do: true

def both(_, false, _),        do: false

def both(_, _, false),        do: false

def both(value, true, right), do: right.(value)

def both(value, left, true),  do: left.(value)

def both(value, left, right) do

  left.(value) and right.(value)

end

def either(_, true, _),          do: true

def either(_, _, true),          do: true

def either(_, false, false),     do: false

def either(value, left, false),  do: left.(value)

def either(value, false, right), do: right.(value)

def either(value, left, right) do

  left.(value) or right.(value)

end

However, the support for boolean operands might not end up being the most readable.

[Louis Pilfold]

Hi

What would this add to the language that we don't already have? It seems to overlap with &&, ||, and, or, Enum.any, and Enum.all. I would rather we have fewer ways in the standard library to write the same thing, rather than more, so new people coming to this language have less special cases, syntaxes and rules to learn.

This could be implemented today as a macro quite easily. Perhaps make a hex package for this as then people can use this if they wish and we don't have to modify the standard library and wait for another Elixir released.

Cheers,
Louis

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