Why “do…while” does not exist in F#

Question

I cannot find \"do...while...\"

I have to code like this:

let bubbleSort a=
    let n = Array.length a
    let mutable swapped = true
    let mutable i =         


        

Answer 1

I do not know about F# very well, but F# is a functional language. Usually, there is no such thing as "for" or "while" loops in functional programming languages.

Functional languages define functions in a mathematical sense (like f(x) => ...). Writing a program comes down to defining and combining a set of mathematical functions. This means that the only way of coding loops is using recursion.

In Mathematics, there is no way of saying:

f(x) => "do 5 times this"

What you'd do is define f like:

                 count > 0  : f(x, count-1)
f(x, count) => {
                 count <= 0 : ...

And then use this function as in:

y = f(x, 5)

This would be exactly how you implement functions in functional languages. At least, this is true for purely functional languages like Haskell...