package reason-standard

  1. Overview
  2. Docs

Module Standard.Tuple

Functions for manipulating pairs of values

type ('a, 'b) t = 'a * 'b

Create

val make : 'a -> 'b -> 'a * 'b

Create a two-tuple with the given values.

The values do not have to be of the same type.

Examples

Tuple.make 3 "Clementine" = (3, "Clementine")
val ofArray : 'a array -> ('a * 'a) option

Create a tuple from the first two elements of an Array.

If the array is longer than two elements, the extra elements are ignored.

If the array is less than two elements, returns None

Examples

Tuple.ofArray [|1; 2|] = Some (1, 2)
Tuple.ofArray [|1|] = None
Tuple.ofArray [|4; 5; 6|] = Some (4, 5)
val ofList : 'a list -> ('a * 'a) option

Create a tuple from the first two elements of a List.

If the list is longer than two elements, the extra elements are ignored.

If the list is less than two elements, returns None

Examples

Tuple.ofList [1; 2] = Some (1, 2)
Tuple.ofList [1] = None
Tuple.ofList [4; 5; 6] = Some (4, 5)
val first : ('a * 'b) -> 'a

Extract the first value from a tuple.

Examples

Tuple.first (3, 4) = 3
Tuple.first ("john", "doe") = "john"
val second : ('a * 'b) -> 'b

Extract the second value from a tuple.

Examples

Tuple.second (3, 4) = 4
Tuple.second ("john", "doe") = "doe"

Transform

val mapFirst : ('a * 'b) -> f:('a -> 'x) -> 'x * 'b

Transform the first value in a tuple.

Examples

Tuple.mapFirst ~f:String.reverse ("stressed", 16) = ("desserts", 16)
Tuple.mapFirst ~f:String.length ("stressed", 16) = (8, 16)
val mapSecond : ('a * 'b) -> f:('b -> 'c) -> 'a * 'c

Transform the second value in a tuple.

Examples

Tuple.mapSecond ~f:Float.squareRoot ("stressed", 16.) = ("stressed", 4.)
Tuple.mapSecond ~f:(~-) ("stressed", 16) = ("stressed", -16)
val mapEach : ('a * 'b) -> f:('a -> 'x) -> g:('b -> 'y) -> 'x * 'y

Transform both values of a tuple, using f for the first value and g for the second.

Examples

Tuple.mapEach ~f:String.reverse ~g:Float.squareRoot ("stressed", 16.) = ("desserts", 4.)
Tuple.mapEach ~f:String.length ~g:(~-) ("stressed", 16) = (8, -16)
val mapAll : ('a * 'a) -> f:('a -> 'b) -> 'b * 'b

Transform both of the values of a tuple using the same function.

mapAll can only be used on tuples which have the same type for each value.

Examples

Tuple.mapAll ~f:(Int.add 1) (3, 4, 5) = (4, 5, 6)
Tuple.mapAll ~f:String.length ("was", "stressed") = (3, 8)
val swap : ('a * 'b) -> 'b * 'a

Switches the first and second values of a tuple.

Examples

Tuple.swap (3, 4) = (4, 3)
Tuple.swap ("stressed", 16) = (16, "stressed")

Convert

val toArray : ('a * 'a) -> 'a array

Turns a tuple into an Array of length two.

This function can only be used on tuples which have the same type for each value.

Examples

Tuple.toArray (3, 4) = [|3; 4|]
Tuple.toArray ("was", "stressed") = [|"was"; "stressed"|]
val toList : ('a * 'a) -> 'a list

Turns a tuple into a list of length two. This function can only be used on tuples which have the same type for each value.

Examples

Tuple.toList (3, 4) = [3; 4]
Tuple.toList ("was", "stressed") = ["was"; "stressed"]

Compare

val equal : ('a -> 'a -> bool) -> ('b -> 'b -> bool) -> ('a, 'b) t -> ('a, 'b) t -> bool

Test two Tuples for equality, using the provided functions to test the first and second components.

Examples

Tuple.equal Int.equal String.equal (1, "Fox") (1, "Fox") = true
Tuple.equal Int.equal String.equal (1, "Fox") (2, "Hen") = false
val compare : ('a -> 'a -> int) -> ('b -> 'b -> int) -> ('a, 'b) t -> ('a, 'b) t -> int

Compare two Tuples, using the provided functions to compare the first components then, if the first components are equal, the second components.

Examples

Tuple.compare Int.compare String.compare (1, "Fox") (1, "Fox") = 0
Tuple.compare Int.compare String.compare (1, "Fox") (1, "Eel") = 1
Tuple.compare Int.compare String.compare (1, "Fox") (2, "Hen") = -1