I'm quickly learning ruby at my new job. Today's POLA (principle of least astonishment) violation is blamed on my expectations of 'if' behavior in Ruby from what I know from Python, C, and other languages.

Non-nil values are considered true:

["0", [], {}, "", 0, true, false, nil].each { |x|
  bool = (x) ? true : false
  puts "#{x.inspect}: #{bool}"
}

"0": true
[]: true
{}: true
"": true
0: true
true: true
false: false
nil: false

I mostly expected every one of the outputs here except for the literal 0 value being true. Noted for future reference.

Additionally confusing, is that Integer() will barf on most non-number inputs, but for some reason "nil" means 0.

irb(main):002:0> Integer(nil)
=> 0

Unexpected.