Parameter Make.2-H2

type t

The type of the hashtable keys.

val equal : t -> t -> bool

The equality predicate used to compare keys.

val hash : t -> int

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 (provided objects do not contain floats)
  • ((fun x y -> compare x y = 0), Hashtbl.hash) for comparing objects by structure and handling Stdlib.nan correctly
  • ((==), Hashtbl.hash) for comparing objects by physical equality (e.g. for mutable or cyclic objects).