Tuples in F#

Tuples are collections where each element can be of different type. If you have a C# or Python background then you must be familiar with tuples. A tuple can be used to return multiple values from a function without having to declare an object for it.

Here’s a tuple with 5 elements:

let addThreeNumbers x y z = x + y + z
let myFirstTuple = (45, "hello world", 5., true, addThreeNumbers)

This tuple has an integer, a string, a float, a boolean and a function in it.

val myFirstTuple : int * string * float * bool * (int -> int -> int -> int) = (45, “hello world”, 5.0, true, )

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For-each loops in F#

For-each loops in F# are declared using the keywords for, in and do.

Here’s how to iterate through a list of integers:

let myList = [1..10]
let loopTester = 
    for i in myList do
        printfn "Current value: %i" i

Executing the function loopTester gives the following output:

Current value: 1
Current value: 2
Current value: 3
Current value: 4
Current value: 5
Current value: 6
Current value: 7
Current value: 8
Current value: 9
Current value: 10

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Records in F#

Records in F# are similar to objects in OOP languages. They can have named fields and other members. However, like many other elements in F#, they are immutable.

Here’s how to declare a record of type Book with a couple of fields and a function:

type Book = {
    title: string;
    numberOfPages:int;
    author: string
} 
with member this.takesLongTimeToRead = this.numberOfPages > 500

Here’s how we can declare a new Book:

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