For statement in OCaml without integers

Question

For learning reasons, I would like to use for loops in OCaml instead of recursion.

I've researched a bit and applied one example of ( https://ocaml.org/learn/tutorials/camlp4_3.10/foreach_tutorial.html ):

let a_list = ["hello"; "world"] in
for s in a_list do
  print_endline s
done

This makes sense. However, when I look at it (on Visual Studio, for instance), it tells me that 's' is an int variable. Therefore, I cannot do stuff like (where 'a', 'b',... are variables of any type):

let a_list = [a;b;c...] in
for s in a_list do
  match s with
    ...
done

Is there not a way to use the for statement like in Python? I mean, to use 's in list' and that s's type will be its type and not 'int'?

There is something I do not see there.

Thanks in advance!

Answer 1

There is no foreach in OCaml. Recursion is the idiomatic style, or if you really want to avoid recursion, you can use while loop. For loop only iterate on integers.

You might be confused on the nature of the tutorial that you are linking: this is a tutorial for implementing a (old style) syntax extension for OCaml, and not a tutorial on using for loop in OCaml.