Empty collections behave that way for `set.all { it.test }` to be equivalent to `!set.any { !it.test...

# stdlib

[aimozg]

Empty collections behave that way for set.all { it.test } to be equivalent to !set.any { !it.test } in all cases. Found more information here: https://en.wikipedia.org/wiki/Vacuous_truth and http://math.stackexchange.com/questions/202452/why-is-predicate-all-as-in-allset-true-if-the-set-is-empty

[aimozg]

Though we have to agree that

"".all { it.isDigit() && !it.isDigit() && it === Math.random() }

is true, we won't get

list.map{...}.filter{...}.all{ test }
list.map{...}.filter{...}.none{ !test }

producing different results in runtime when encountering empty collection at the last step after all `map`s and `filter`s