module type HashedType : sig ... end
The input signature of the functor Hashtbl.Make
.
t
is the type of keys.
equal
is the equality predicate used to compare keys.
hash
is a hashing function on keys, returning a non-negative
integer. It must be such that if two keys are equal according
to equal
, then they must have identical hash values as computed
by hash
.
Examples: suitable (equal
, hash
) pairs for arbitrary key
types include
((=)
, Hashtbl.hash
) for comparing objects by structure, and
((==)
, Hashtbl.hash
) for comparing objects by addresses
(e.g. for mutable or cyclic keys).