increment-option

Increment optional value

In OCaml you can use values of type option via pattern matching. For example, the following function takes as input a value of type int option and returns 0 or the value within the Some tag:

let f x = match x with
  None -> 0
| Some x -> x;;

f (Some 3);;
f None;;

Write a function of type:

incr_opt : int option -> int option

that takes an int option and returns Some(value + 1) if the input is Some(value). If the input is None, return None.

Examples

incr_opt (Some 5) = Some 6
incr_opt None = None