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package containers
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Hash combinators

Definitions

type hash = int

A hash value is a positive integer.

type 'a t = 'a -> hash

A hash function for values of type 'a.

val const : hash -> _ t

const h hashes any value into h. Use with caution!.

val const0 : _ t

Always return 0. Useful for ignoring elements. Example: Hash.(pair string const0) will map pairs ("a", 1) and ("a", 2) to the same hash, but not the same as ("b", 1).

  • since 1.5
val int : int t
val bool : bool t
val char : char t
val int32 : int32 t
val int64 : int64 t
val nativeint : nativeint t
val slice : string -> int -> int t

slice s i len state hashes the slice i, ... i+len-1 of s into state.

val string : string t
val list : 'a t -> 'a list t
val array : 'a t -> 'a array t
val opt : 'a t -> 'a option t
val pair : 'a t -> 'b t -> ('a * 'b) t
val triple : 'a t -> 'b t -> 'c t -> ('a * 'b * 'c) t
val quad : 'a t -> 'b t -> 'c t -> 'd t -> ('a * 'b * 'c * 'd) t
val if_ : bool -> 'a t -> 'a t -> 'a t

Decide which hash function to use depending on the boolean.

val poly : 'a t

The regular polymorphic hash function. poly x is Hashtbl.hash x.

val list_comm : 'a t -> 'a list t

Commutative version of list. Lists that are equal up to permutation will have the same hash.

  • since 1.0
val array_comm : 'a t -> 'a array t

Commutative version of array. Arrays that are equal up to permutation will have the same hash.

  • since 1.0

Base hash combinators

val combine : 'a t -> hash -> 'a -> hash
val combine2 : hash -> hash -> hash
val combine3 : hash -> hash -> hash -> hash
val combine4 : hash -> hash -> hash -> hash -> hash
val combine5 : hash -> hash -> hash -> hash -> hash -> hash
  • since 2.1
val combine6 : hash -> hash -> hash -> hash -> hash -> hash -> hash
  • since 2.1

Iterators

type 'a sequence = ('a -> unit) -> unit
type 'a gen = unit -> 'a option
type 'a klist = unit -> [ `Nil | `Cons of 'a * 'a klist ]
val seq : 'a t -> 'a sequence t
val gen : 'a t -> 'a gen t
val klist : 'a t -> 'a klist t