The type of the hashtable keys.
The equality predicate used to compare keys.
A hashing function on keys. It must be such that if two keys are
equal according to
equal, then they 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,
(
(fun x y -> compare x y = 0),
Hashtbl.hash)
for comparing objects by structure and handling
Pervasives.nan
correctly, and
(
(==),
Hashtbl.hash) for comparing objects by addresses
(e.g. for cyclic keys).