Id
Provide utiliites to create identified comparators or hashes for data structures used below.
It create a unique identifer per module of functions so that different data structures with slightly different comparison functions won't mix.
hash
type hash<'a, 'id>
('a, 'id) hash
Its runtime represenation is a hash
function, but signed with a
type parameter, so that different hash functions type mismatch
eq
type eq<'a, 'id>
('a, 'id) eq
Its runtime represenation is an eq
function, but signed with a
type parameter, so that different hash functions type mismatch
cmp
type cmp<'a, 'id>
('a,'id) cmp
Its runtime representation is a cmp
function, but signed with a
type parameter, so that different hash functions type mismatch
comparable
type comparable<'key, 'id> = module(Comparable
with type identity = 'id
with type t = 'key)
('key, 'id) cmparable
is a module of functions, here it only includes cmp
.
Unlike normal functions, when created, it comes with a unique identity (guaranteed by the type system).
It can be created using function comparableU
or comparable
.
The idea of a unique identity when created is that it makes sure two sets would type mismatch if they use different comparison function
comparableU
let comparableU: (
~cmp: ('a, 'a) => int,
) => module(Comparable with type t = 'a)
comparable
let comparable: (
~cmp: ('a, 'a) => int,
) => module(Comparable with type t = 'a)
Examples
RESCRIPTmodule C = (
val Belt.Id.comparable ~cmp:(compare : int -> int -> int)
)
let m = Belt.Set.make(module C)
Note that the name of C can not be ignored
hashable
type hashable<'key, 'id> = module(Hashable
with type identity = 'id
with type t = 'key)
('key, 'id) hashable
is a module of functions, here it only includes hash
, eq
.
Unlike normal functions, when created, it comes with a unique identity (guaranteed by the type system).
It can be created using function hashableU
or hashable
.
The idea of a unique identity when created is that it makes sure two hash sets would type mismatch if they use different comparison function
hashableU
let hashableU: (
~hash: 'a => int,
~eq: ('a, 'a) => bool,
) => module(Hashable with type t = 'a)
hashable
let hashable: (
~hash: 'a => int,
~eq: ('a, 'a) => bool,
) => module(Hashable with type t = 'a)
getHashInternal
let getHashInternal: hash<'a, 'id> => 'a => int
getEqInternal
let getEqInternal: eq<'a, 'id> => ('a, 'a) => bool
getCmpInternal
let getCmpInternal: cmp<'a, 'id> => ('a, 'a) => int