Iterate over a list while tracking index?

Question

I was just wondering if there was a way to iterate over a list while also keeping track of its index in OCaml? That would be really useful - I'm trying to stagger each element of a list by its index value. Thanks.

Answer 1

There is a function List.iteri that iterates over a list while supplying the index of each element. But if you want to generate a new list, it might be more appropriate to use List.mapi, which supplies the index of each element and builds up a new list (of the same size).

# List.mapi (fun index element -> element + index) [0;1;2;3];;
- : int list = [0; 2; 4; 6]

Documentation on OCaml List iterator functions.