A tuple is a grouping of unnamed but ordered values, possibly of different types. Tuples can either be reference types or structs.
The basic syntax of tuples in F# is as follows.
(element, ... , element)
struct(element, ... ,element )
Tuples include pairs, triples, and so on, of the same or different types. The following examples show different types of tuples.
// Tuple of two strings.
let tuple1 = ( "Hello", "World" )
// Triple of double.
let tuple2 = ( 1.1, 2.2, 3.3 )
// Tuple of unknown types.
let a = 2
let b = 4
let tuple3 = ( a, b )
// Tuple that has mixed types.
let tuple4 = ( "F#", 1, 2.0 )
// Tuple of integer expressions.
let tuple5 = ( a * 4, b + 7)
// Struct Tuple of floats
let tuple6 = struct (1.025f, 1.5f)
You can also deconstruct a tuple via pattern matching using let binding.
let (x, y) = (33, 27)
Console.WriteLine("x = {0}, y = {1}", x, y)
// Or as a struct
let struct (c, d) = struct (14, 29)
Console.WriteLine("c = {0}, d = {1}", c, d)
You can copy elements from a reference tuple into a struct tuple as shown below.
// Create a reference tuple
let (a, b) = (31, 52)
// Construct a struct tuple from it
let struct (c, d) = struct (a, b)
If you need only one element of the tuple, the wildcard character (the underscore) can be used to avoid creating a new name for a value that you do not need.
let (name, _) = ("Mark", 25)
The functions fst and snd (reference tuples only) return the first and second elements of a tuple, respectively.
let c = fst (13, 27)
let d = snd (13, 27)