Nothing to Compare

How does nothing (as in nil, null, or nan) compare to nothing?

Equality Equality

==	`nil`	`0`	`0.0`	`0i`	`0r`	`NaN`¹
`nil`	true	false	false	false	false	false
`0`	false	true	true	true	true	false
`0.0`	false	true	true	true	true	false
`0i`	false	true	true	true	true	false
`0r`	false	true	true	true	true	false
`NaN`	false	false	false	false	false	false

¹ Get a reference to NaN via Float::NAN or by executing 0.0/0

Take Aways

0 == 0.0 == 0i == 0r
NaN != NaN

Fancy Equality

===	`nil`	`0`	`0.0`	`0i`	`0r`	`NaN`
`nil`	true	false	false	false	false	false
`0`	false	true	true	true	true	false
`0.0`	false	true	true	true	true	false
`0i`	false	true	true	true	true	false
`0r`	false	true	true	true	true	false
`NaN`	false	false	false	false	false	false

Take Away

Same as == for null values

Hash Key Equality

.eql?	`nil`	`0`	`0.0`	`0i`	`0r`	`NaN`
`nil`	true	false	false	false	false	false
`0`	false	true	false	false	false	false
`0.0`	false	false	true	false	false	false
`0i`	false	false	false	true	false	false
`0r`	false	false	false	false	true	false
`NaN`	false	false	false	false	false	false

Take Away

Different types of 0s do not .eql?

Object Identity

.equal?	`nil`	`0`	`0.0`	`0i`	`0r`	`NaN`
`nil`	true	false	false	false	false	false
`0`	false	true	false	false	false	false
`0.0`	false	false	true	false	false	false
`0i`	false	false	false	true	false	false
`0r`	false	false	false	false	true	false
`NaN`	false	false	false	false	false	true

Take Away

NaN is the same Object as NaN

Also See

Episode 55: Struggling Four Equality

More Idiosyncratic Ruby