Re: [Caml-list] use of ";;" when teaching Ocaml

["Daniel Bünzli" <daniel.buenzli@erratique.ch>]

Le lundi, 22 juin 2015 à 14:31, Alan Schmitt a écrit :
> 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?
  
Leaving the ;; polemic aside (which you can also write in the second form if you want to), I would definitively teach the second form as OCaml's default set of warnings don't warn you about potential partial applications on the lines of the first form. This can lead to puzzling "nothing happens" bugs, especially for a new commer.

For example:  

output_string stdout;;

compiles without a hitch — that's also why it should be, as you rightly propose, `let () = …` and not `let _ = …`

Best,

Daniel