Increment value in F#

Question

Maybe it\'s too simple thing to do, but I can\'t find any answer in the web
I\'m try to Increment value in F# (like count++ in C#).
I don\'t want to use

Answer 1

If you don't want to use mutable then you can't really do a destructive update like ++ is in C#. You could shadow a variable with a new one with the same name e.g.

let x = 4;
let x = x + 1 in (x+4)  //returns 8

although you couldn't write this as a function.

EDIT: If do want to use mutable variables then you can create a function which modifies a ref:

let increment (ir: int ref) = ir := !ir + 1

You can then use it as

let i = ref 1
increment i
let iv = !i    //iv contains 2

As Tomas points out in his answer, this function already exists and is called incr.