Belt.Map
The top level provides generic immutable map operations.
It also has three specialized inner modules Belt.Map.Int
, Belt.Map.String
and
Belt.Map.Dict
: This module separates data from function which is more verbose but slightly more efficient
A immutable sorted map module which allows customize compare behavior.
The implementation uses balanced binary trees, and therefore searching and insertion take time logarithmic in the size of the map.
For more info on this module's usage of identity, `make` and others, please see the top level documentation of Belt, A special encoding for collection safety.
Example usage:
module PairComparator = Belt.Id.MakeComparable(struct
type t = int * int
let cmp (a0, a1) (b0, b1) =
match Pervasives.compare a0 b0 with
| 0 -> Pervasives.compare a1 b1
| c -> c
end)
let myMap = Belt.Map.make ~id:(module PairComparator)
let myMap2 = Belt.Map.set myMap (1, 2) "myValue"
The API documentation below will assume a predeclared comparator module for integers, IntCmp
module Int : sig ... end
Specalized when key type is int
, more efficient than the generic type, its compare behavior is fixed using the built-in comparison
module String : sig ... end
specalized when key type is string
, more efficient than the generic type, its compare behavior is fixed using the built-in comparison
module Dict : sig ... end
This module seprate identity from data, it is a bit more verboe but slightly more efficient due to the fact that there is no need to pack identity and data back after each operation
('key, 'identity) t
'key
is the field type
'value
is the element type
'identity
the identity of the collection
The identity needed for making an empty map
make ~id
creates a new map by taking in the comparator
let m = Belt.Map.make ~id:(module IntCmp)
val isEmpty : (_, _, _) t -> bool
isEmpty m
checks whether a map m is empty
isEmpty (fromArray [|1,"1"|] ~id:(module IntCmp)) = false
val has : ('k, 'v, 'id) t -> 'k -> bool
has m k
checks whether m has the key k
has (fromArray [|1,"1"|] ~id:(module IntCmp)) 1 = true
val cmpU :
('k, 'v, 'id) t ->
('k, 'v, 'id) t ->
('v -> 'v -> int) Js.Fn.arity2 ->
int
cmp m0 m1 vcmp
Total ordering of map given total ordering of value function.
It will compare size first and each element following the order one by one.
val eqU :
('k, 'v, 'id) t ->
('k, 'v, 'id) t ->
('v -> 'v -> bool) Js.Fn.arity2 ->
bool
eq m1 m2 veq
tests whether the maps m1
and m2
are equal, that is, contain equal keys and associate them with equal data. veq
is the equality predicate used to compare the data associated with the keys.
val findFirstByU :
('k, 'v, 'id) t ->
('k -> 'v -> bool) Js.Fn.arity2 ->
('k * 'v) option
val findFirstBy : ('k, 'v, 'id) t -> ('k -> 'v -> bool) -> ('k * 'v) option
findFirstBy m p
uses funcion f
to find the first key value pair to match predicate p
.
let s0 = fromArray ~id:(module IntCmp) [|4,"4";1,"1";2,"2,"3""|];;
findFirstBy s0 (fun k v -> k = 4 ) = option (4, "4");;
val forEachU : ('k, 'v, 'id) t -> ('k -> 'v -> unit) Js.Fn.arity2 -> unit
val forEach : ('k, 'v, 'id) t -> ('k -> 'v -> unit) -> unit
forEach m f
applies f
to all bindings in map m
. f
receives the 'k as first argument, and the associated value as second argument. The bindings are passed to f
in increasing order with respect to the ordering over the type of the keys.
let s0 = fromArray ~id:(module IntCmp) [|4,"4";1,"1";2,"2,"3""|];;
let acc = ref [] ;;
forEach s0 (fun k v -> acc := (k,v) :: !acc);;
!acc = [4,"4"; 3,"3"; 2,"2"; 1,"1"]
val reduceU :
('k, 'v, 'id) t ->
'acc ->
('acc -> 'k -> 'v -> 'acc) Js.Fn.arity3 ->
'acc
val reduce : ('k, 'v, 'id) t -> 'acc -> ('acc -> 'k -> 'v -> 'acc) -> 'acc
reduce m a f
computes (f kN dN ... (f k1 d1 a)...)
, where k1 ... kN
are the keys of all bindings in m
(in increasing order), and d1 ... dN
are the associated data.
let s0 = fromArray ~id:(module IntCmp) [|4,"4";1,"1";2,"2,"3""|];;
reduce s0 [] (fun acc k v -> (k,v) acc ) = [4,"4";3,"3";2,"2";1,"1"];;
val everyU : ('k, 'v, 'id) t -> ('k -> 'v -> bool) Js.Fn.arity2 -> bool
val every : ('k, 'v, 'id) t -> ('k -> 'v -> bool) -> bool
every m p
checks if all the bindings of the map satisfy the predicate p
. Order unspecified
val someU : ('k, 'v, 'id) t -> ('k -> 'v -> bool) Js.Fn.arity2 -> bool
val some : ('k, 'v, 'id) t -> ('k -> 'v -> bool) -> bool
some m p
checks if at least one binding of the map satisfy the predicate p
. Order unspecified
val size : ('k, 'v, 'id) t -> int
size s
size (fromArray [2,"2"; 2,"1"; 3,"3"] ~id:(module IntCmp)) = 2 ;;
val toArray : ('k, 'v, 'id) t -> ('k * 'v) array
toArray s
toArray (fromArray [2,"2"; 1,"1"; 3,"3"] ~id:(module IntCmp)) = [1,"1";2,"2";3,"3"]
fromArray kvs ~id
toArray (fromArray [2,"2"; 1,"1"; 3,"3"] ~id:(module IntCmp)) = [1,"1";2,"2";3,"3"]
val keysToArray : ('k, 'v, 'id) t -> 'k array
keysToArray s
keysToArray (fromArray [2,"2"; 1,"1"; 3,"3"] ~id:(module IntCmp)) =
[|1;2;3|];;
val valuesToArray : ('k, 'v, 'id) t -> 'v array
valuesToArray s
valuesToArray (fromArray [2,"2"; 1,"1"; 3,"3"] ~id:(module IntCmp)) =
[|"1";"2";"3"|];;
val minKey : ('k, _, _) t -> 'k option
minKey s
val minKeyUndefined : ('k, _, _) t -> 'k Js.undefined
See minKey
val maxKey : ('k, _, _) t -> 'k option
maxKey s
val maxKeyUndefined : ('k, _, _) t -> 'k Js.undefined
See maxKey
val minimum : ('k, 'v, _) t -> ('k * 'v) option
minimum s
val minUndefined : ('k, 'v, _) t -> ('k * 'v) Js.undefined
See minimum
val maximum : ('k, 'v, _) t -> ('k * 'v) option
maximum s
val maxUndefined : ('k, 'v, _) t -> ('k * 'v) Js.undefined
See maximum
val get : ('k, 'v, 'id) t -> 'k -> 'v option
get s k
get (fromArray [2,"2"; 1,"1"; 3,"3"] ~id:(module IntCmp)) 2 =
Some "2";;
get (fromArray [2,"2"; 1,"1"; 3,"3"] ~id:(module IntCmp)) 2 =
None;;
val getUndefined : ('k, 'v, 'id) t -> 'k -> 'v Js.undefined
See get
remove m x
when x
is not in m
, m
is returned reference unchanged.
let s0 = (fromArray [2,"2"; 1,"1"; 3,"3"] ~id:(module IntCmp));;
let s1 = remove s0 1;;
let s2 = remove s1 1;;
s1 == s2 ;;
keysToArray s1 = [|2;3|];;
removeMany s xs
Removing each of xs
to s
, note unlike remove
, the reference of return value might be changed even if none in xs
exists s
set m x y
returns a map containing the same bindings as m
, with a new binding of x
to y
. If x
was already bound in m
, its previous binding disappears.
let s0 = (fromArray [2,"2"; 1,"1"; 3,"3"] ~id:(module IntCmp));;
let s1 = set s0 2 "3";;
valuesToArray s1 = ["1";"3";"3"];;
val updateU :
('k, 'v, 'id) t ->
'k ->
('v option -> 'v option) Js.Fn.arity1 ->
('k, 'v, 'id) t
update m x f
returns a map containing the same bindings as m
, except for the binding of x
. Depending on the value of y
where y
is f (get x m)
, the binding of x
is added, removed or updated. If y
is None
, the binding is removed if it exists; otherwise, if y
is Some z
then x
is associated to z
in the resulting map.
mergeMany s xs
Adding each of xs
to s
, note unlike add
, the reference of return value might be changed even if all values in xs
exist s
val mergeU :
('k, 'v, 'id) t ->
('k, 'v2, 'id) t ->
('k -> 'v option -> 'v2 option -> 'v3 option) Js.Fn.arity3 ->
('k, 'v3, 'id) t
val merge :
('k, 'v, 'id) t ->
('k, 'v2, 'id) t ->
('k -> 'v option -> 'v2 option -> 'v3 option) ->
('k, 'v3, 'id) t
merge m1 m2 f
computes a map whose keys is a subset of keys of m1
and of m2
. The presence of each such binding, and the corresponding value, is determined with the function f
.
val keepU :
('k, 'v, 'id) t ->
('k -> 'v -> bool) Js.Fn.arity2 ->
('k, 'v, 'id) t
keep m p
returns the map with all the bindings in m
that satisfy predicate p
.
val partitionU :
('k, 'v, 'id) t ->
('k -> 'v -> bool) Js.Fn.arity2 ->
('k, 'v, 'id) t * ('k, 'v, 'id) t
partition m p
returns a pair of maps (m1, m2)
, where m1
contains all the bindings of s
that satisfy the predicate p
, and m2
is the map with all the bindings of s
that do not satisfy p
.
split x m
returns a tuple (l r), data
, where l
is the map with all the bindings of m
whose 'k is strictly less than x
; r
is the map with all the bindings of m
whose 'k is strictly greater than x
; data
is None
if m
contains no binding for x
, or Some v
if m
binds v
to x
.
val mapU : ('k, 'v, 'id) t -> ('v -> 'v2) Js.Fn.arity1 -> ('k, 'v2, 'id) t
map m f
returns a map with same domain as m
, where the associated value a
of all bindings of m
has been replaced by the result of the application of f
to a
. The bindings are passed to f
in increasing order with respect to the ordering over the type of the keys.
val mapWithKeyU :
('k, 'v, 'id) t ->
('k -> 'v -> 'v2) Js.Fn.arity2 ->
('k, 'v2, 'id) t
mapWithKey m f
The same as map
except that f
is supplied with one more argument: the key
val getData : ('k, 'v, 'id) t -> ('k, 'v, 'id) Belt__.Belt_MapDict.t
getData s0
Advanced usage only