F# For Dummys - Day 11 Collections Tuple

Today we learn Tuple, as the first data structure of Collections
tuple is a simple data structure that combine elements together. These elements can be different types

(1, 2)

// Triple of strings.
("one", "two", "three")

// Tuple of generic types.
(a, b)

// Tuple that has mixed types.
("one", 1, 2.0)

// Tuple of integer expressions.
(a + 1, b + 1)

let's do some practices

• defining a tuple with 2 elements

let person = ("John", 30)
let (name, age) = person   // this is unpack, unpack first element of person to name, second to age

printfn "Name: %s, Age: %d" name age

you can also get the element by fst snd for a tuple with 2 elements like below

let person = ("John", 30)
let name = fst person   // "John"
let age = snd person    // 30

printfn "Name: %s, Age: %d" name age

• defining a tuple with 3 elements

let point = (3, 4, 5)
let (x, y, z) = point

printfn "Point coordinates: x = %d, y = %d, z = %d" x y z

there is no trd to get third element of tuple with 3 elements
there is no empty tuple, () is not empty tuple, it's more like Null

• ignore element of tuple

let point = (3, 4, 5)
let (x, _, z) = point

printfn "Point coordinates: x = %d, z = %d" x z

the second element 4 will be ignored

• return a tuple in function

let getPersonInfo() = ("John", 30)
let (personName, personAge) = getPersonInfo()

printfn "Person Name: %s, Person Age: %d" personName personAge

• access elements of tuple in match

let print tuple1 =
   match tuple1 with
    | (a, b) -> printfn "Pair %A %A" a b // %A can format any type

print (1, 2)
print ("John", 30)

Tuples are particularly useful when you need to return multiple values from a function or when you want to combine several values together