What are the differences between standard equality operators (==, ===, eql?, equal?)?

== checks for structural value equality. === is the case equality operator used in case/when structures. eql? checks both value equality and strict type equality. equal? checks for identical object memory IDs.

== is the generic equality operator, overridden by classes to compare values (e.g., 1 == 1.0 is true). === is commonly called the triple-equals or case operator; it checks if the right side 'belongs to' or is a member of the left-side condition (e.g., Integer === 1 is true). eql? is stricter; it is used by Hash to determine key matching and checks both value and type (1.eql?(1.0) is false). equal? is the absolute strictest, checking pointer identity (a.equal?(b) is true only if a.object_id == b.object_id).