Crate cons 

cons

Quick and simple hash-consing implementations for a variety of internally mutable HashMaps/HashSets (use the features to select the ones you want).

Traits

CanGC

A trait implemented by values which can be garbage collected

Cons

A trait implemented by sets which can be used for hash-consing values of type C using keys of type Q

Uncons

A trait implemented by sets which can be used to un-cons values of type C