how to to do the "noop but return unit" in OCaml

Question

I want to print a list of strings after going through a pattern matching just to get into this powerful functionality.

How can I express the "do-nothing-but-return-unit" operation ?

What I mean is:

let print_nodes nodes =
  match nodes with
      []     -> (* here i want to noop *)
    | s :: t -> print_string s; print_nodes t

(I know that I can use the iter function but i was just curious) — Jack, Jun 14 '10 at 13:17

score 26 · Accepted Answer · answered Jun 14 '10 at 13:22

26

You can simply write ().

See Variant values in the manual: () is how you build the unit value.

answered Jun 14 '10 at 13:22

tonio

Ok, just searched for it and got it! Sorry for this dumb/simple question but haven't found the () empty unit until now :/ – Jack Jun 14 '10 at 13:23
1

@Jack Well, it is not used that often :) If you write in a purely functional style (without side-effects) you never have to use it at all... – Pascal Cuoq Jun 15 '10 at 03:34

1 Answers1