any? and empty? are not antonyms

What I Learned

[nil].any? # => false

Because my expectation was it to be true. My conception of Enumerable#any? was that it returns true if it has any record. Not only that, my metal shortcut it was that was an antonym to Array#empty?.

And why exactly is this interesting?

1. Ruby has many methods which mean and do the same thing. Like Array#size and Array#length and, to some extent, Enumerable#count.
2. Ruby has many methods which mean and do opposite things. Like Enumerable#all? and Enumerable#none?
3. Knowing what empty? does and of 1. and 2., I believed that any? would do its opposite.

Enlightenment came about during code review where I was suggesting to remove the unnecessary if conditional

if collection.any?
  collection.map do |i|
…

After discussing the problem and poking the code we were able to remove the if by preventing nil from getting into collection.