Module Tag

Tags on runtime boxed values.

include Identifiable.S
type t
module T : Identifiable.Thing with type t = t
include Identifiable.Thing with type t := T.t
include Hashtbl.HashedType with type t := T.t
val equal : T.t -> T.t -> bool

The equality predicate used to compare keys.

val hash : T.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.

The hash value of a key should remain constant as long as the key is in the table. In particular, if the hash function depends on mutable key data, then that data must not be mutated while the key is in the table. Similarly, as the hash function may be called while the table itself is being modified, it should avoid accessing the table as part of its computation.

Examples: suitable (equal, hash) pairs for arbitrary key types include

  • ((=), hash) for comparing objects by structure (provided objects do not contain floats)
  • ((fun x y -> compare x y = 0), hash) for comparing objects by structure and handling Stdlib.nan correctly
  • ((==), hash) for comparing objects by physical equality (e.g. for mutable or cyclic objects).
include Map.OrderedType with type t := T.t
val output : out_channel -> T.t -> unit
val print : Format.formatter -> T.t -> unit
module Set : Identifiable.Set with module T := T
module Map : Identifiable.Map with module T := T
module Tbl : Identifiable.Tbl with module T := T
val create_exn : int -> t
val to_int : t -> int
val zero : t
val object_tag : t
val compare : t -> t -> int