To my experience, this is a bad practice, that produces lots of confusion
to students.
They should clearly understand difference between writing code in a
toplevel and normal programming. A difference between
definition on a module level, and an expression. I usually say that `;;` is
not a part of a language, but just a part of a toplevel
command syntax (as well as toplevel directives), and strictly require not
to put `;;` in code.

On Mon, Jun 22, 2015 at 9:31 AM, Alan Schmitt <
alan.schmitt@polytechnique.org> wrote:

> Hello,
>
> In my Ocaml class, I tend to promote the use of ";;" to separate phrases
> (I'm basically following
>
> http://ocaml.org/learn/tutorials/structure_of_ocaml_programs.html#Usingandomittingand
> although I was not aware of this page when I created the course). My
> motivation is to minimize the difference between using the top-level and
> writing files.
>
> I am now wondering if this is a good practice. In a nutshell, would you
> rather use
>
> #+begin_src ocaml
> let x = 12;;
> print_endline "Hello World!"
> #+end_src
>
> or
>
> #+begin_src ocaml
> let x = 12
> let () = print_endline "Hello World!"
> #+end_src
>
> when teaching Ocaml?
>
> Thanks,
>
> Alan
>
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