(*
Copyright (c) 2013, Simon Cruanes
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*)

(** {1 Hash combinators}

Combination of hashes based on the
SDBM simple hash (see for instance
{{:http://www.cse.yorku.ca/~oz/hash.html} this page})
*)

type t = int

type 'a hash_fun = 'a -> t

val combine : t -> t -> t
  (** Combine two hashes. Non-commutative. *)

val (<<>>) : t -> t -> t
  (** Infix version of {!combine} *)

val hash_int : int -> t
val hash_int2 : int -> int -> t
val hash_int3 : int -> int -> int -> t
val hash_int4 : int -> int -> int -> int -> t

val hash_string : string -> t

val hash_list : 'a hash_fun -> t -> 'a list hash_fun
(** Hash a list. Each element is hashed using [f]. *)

val hash_array : 'a hash_fun -> t -> 'a array hash_fun

val hash_pair : 'a hash_fun -> 'b hash_fun -> ('a * 'b) hash_fun
val hash_triple : 'a hash_fun -> 'b hash_fun -> 'c hash_fun -> ('a * 'b * 'c) hash_fun

type 'a sequence = ('a -> unit) -> unit
type 'a gen = unit -> 'a option
type 'a klist = [`Nil | `Cons of 'a * (unit -> 'a klist)]

val hash_seq : 'a hash_fun -> t -> 'a sequence hash_fun
val hash_gen : 'a hash_fun -> t -> 'a gen hash_fun
val hash_klist : 'a hash_fun -> t -> 'a klist hash_fun