Idiosyncratic Ruby: Nothing to Compare

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

Equality Equality

== nil 0 0.0 0i 0r NaN¹ 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

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