Module Ghash

Hash plugin.

For type declaration type ('a,'b,...) typ = ... it will create a transformation function with type

(GT.H.t -> 'a -> GT.H.t * 'a) -> (GT.H.t -> 'b -> GT.H.t * 'b) -> ... -> GT.H.t -> ('a,'b,...) typ -> GT.H.t * ('a,'b,...) typ

which takes a value and hashtable (possibly on-empty) and returns hash concsed representation of the value with (maybe) update hashtable.