From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <daniel.buenzli@erratique.ch>
X-Original-To: caml-list@sympa.inria.fr
Delivered-To: caml-list@sympa.inria.fr
Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr [192.134.164.83])
	by sympa.inria.fr (Postfix) with ESMTPS id 969947EEEF
	for <caml-list@sympa.inria.fr>; Mon, 22 Jun 2015 19:04:13 +0200 (CEST)
Received-SPF: None (mail2-smtp-roc.national.inria.fr: no sender
  authenticity information available from domain of
  daniel.buenzli@erratique.ch) identity=pra;
  client-ip=74.55.86.74;
  receiver=mail2-smtp-roc.national.inria.fr;
  envelope-from="daniel.buenzli@erratique.ch";
  x-sender="daniel.buenzli@erratique.ch";
  x-conformance=sidf_compatible
Received-SPF: None (mail2-smtp-roc.national.inria.fr: no sender
  authenticity information available from domain of
  daniel.buenzli@erratique.ch) identity=mailfrom;
  client-ip=74.55.86.74;
  receiver=mail2-smtp-roc.national.inria.fr;
  envelope-from="daniel.buenzli@erratique.ch";
  x-sender="daniel.buenzli@erratique.ch";
  x-conformance=sidf_compatible
Received-SPF: None (mail2-smtp-roc.national.inria.fr: no sender
  authenticity information available from domain of
  postmaster@smtp.webfaction.com) identity=helo;
  client-ip=74.55.86.74;
  receiver=mail2-smtp-roc.national.inria.fr;
  envelope-from="daniel.buenzli@erratique.ch";
  x-sender="postmaster@smtp.webfaction.com";
  x-conformance=sidf_compatible
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: A0AOAQChP4hVm0pWN0pch2HCVQKCBgEBAQEBARIBAQEBAQgJCwkhLoQjAQEEI1YQCxoCJgICRxAGG4gntEaWFgEBCAEBAQEegSGKJIRTMweCaC+BFAWTfZNxD49/hCCDNgEBAQ
X-IPAS-Result: A0AOAQChP4hVm0pWN0pch2HCVQKCBgEBAQEBARIBAQEBAQgJCwkhLoQjAQEEI1YQCxoCJgICRxAGG4gntEaWFgEBCAEBAQEegSGKJIRTMweCaC+BFAWTfZNxD49/hCCDNgEBAQ
X-IronPort-AV: E=Sophos;i="5.13,660,1427752800"; 
   d="scan'208";a="166692549"
Received: from mail6.webfaction.com (HELO smtp.webfaction.com) ([74.55.86.74])
  by mail2-smtp-roc.national.inria.fr with ESMTP; 22 Jun 2015 19:04:12 +0200
Received: from [172.17.24.98] (global-1-18.nat.csx.cam.ac.uk [131.111.184.18])
	by smtp.webfaction.com (Postfix) with ESMTP id 7560520F5035;
	Mon, 22 Jun 2015 17:04:11 +0000 (UTC)
Date: Mon, 22 Jun 2015 18:04:09 +0100
From: =?utf-8?Q?Daniel_B=C3=BCnzli?= <daniel.buenzli@erratique.ch>
To: Alan Schmitt <alan.schmitt@polytechnique.org>
Cc: OCaml Mailing List <caml-list@inria.fr>
Message-ID: <4E69EBE143614C6E89109247275F03DA@erratique.ch>
In-Reply-To: <m2vbefx41k.fsf@charm-ecran.irisa.fr>
References: <m2vbefx41k.fsf@charm-ecran.irisa.fr>
X-Mailer: sparrow 1.6.4 (build 1178)
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
Subject: Re: [Caml-list] use of ";;" when teaching Ocaml

Le lundi, 22 juin 2015 =C3=A0 14:31, Alan Schmitt a =C3=A9crit :
> I am now wondering if this is a good practice. In a nutshell, would you
> rather use
>=20=20
> #+begin_src ocaml
> let x =3D 12;;
> print_endline "Hello World!"
> #+end_src
>=20=20
> or
>=20=20
> #+begin_src ocaml
> let x =3D 12
> let () =3D print_endline "Hello World!"
> #+end_src
>=20=20
> when teaching Ocaml?
=20=20
Leaving the ;; polemic aside (which you can also write in the second form i=
f you want to), I would definitively teach the second form as OCaml's defau=
lt set of warnings don't warn you about potential partial applications on t=
he lines of the first form. This can lead to puzzling "nothing happens" bug=
s, especially for a new commer.

For example:=20=20

output_string stdout;;

compiles without a hitch =E2=80=94 that's also why it should be, as you rig=
htly propose, `let () =3D =E2=80=A6` and not `let _ =3D =E2=80=A6`

Best,

Daniel