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From: Hendrik Boom <hendrik@topoi.pooq.com>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Newbie comment on constructor syntax
Date: Mon, 9 Nov 2015 05:00:28 -0500
Message-ID: <20151109100028.GA12879@topoi.pooq.com> (raw)
In-Reply-To: <0F7D3B1B3C4B894D824F5B822E3E5A172CE3E747@IRSMSX102.ger.corp.intel.com>

On Mon, Nov 09, 2015 at 08:09:30AM +0000, Soegtrop, Michael wrote:
> Dear Florian, Norman, 
> 
> > > Curiously, the argument is not really a tuple.  This does not work:
> > >
> > > type x = X of int * int
> > > let c = (1, 2) in X c
> > 
> > However the following works:
> > # type x  = X of (int * int);;
> > type x = X of (int * int)
> > # let c = (1, 2) in X c;;
> > - : x = X (1, 2)
> 
> Exactly this is what is quite confusing (for the beginner): constructors are a rather odd mix of multiple arguments and tuples. The notation looks like tuples, both in definition and use, but it isn't. And it is not a multiple argument function either, since currying doesn't work. That adding parenthesis makes it a real tuple doesn't make it better, since at some other places a*b and (a*b) are the same.
> 
> To me this is quite a scar in the beauty of the language - the kind of thing you can't avoid to look at, if you know what I mean. Of cause it is not really an issue. It is just way disappointing for new users to find this kind of imperfection and it gives a little dent in the enthusiasm. But just a little one ;-)

Parentheses should never be used with a meaning other than indicating 
proper grouping, their original function in high school algebra.
OCaml went partway there by abolishing them as syntax for function 
calls.

-- hendrik

  reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-06  9:33 Soegtrop, Michael
2015-11-06 10:04 ` Nicolas Ojeda Bar
2015-11-06 10:31 ` Francois Berenger
2015-11-06 12:20   ` Soegtrop, Michael
2015-11-06 12:34     ` Gabriel Scherer
2015-11-06 13:09       ` Soegtrop, Michael
2015-11-06 14:10         ` Ashish Agarwal
2015-11-06 15:19           ` Soegtrop, Michael
2015-11-06 15:22             ` Ashish Agarwal
2015-11-21 17:24       ` [Caml-list] Notation for currying Hendrik Boom
2015-11-21 17:42         ` Gabriel Scherer
2015-11-21 18:06         ` David Rajchenbach-Teller
2015-11-21 18:56           ` Gabriel Scherer
2015-11-06 12:29 ` [Caml-list] Newbie comment on constructor syntax Jonas Jensen
2015-11-06 12:46   ` Soegtrop, Michael
2015-11-06 12:55     ` Gabriel Scherer
2015-11-08 21:17 ` Florian Weimer
2015-11-08 22:51   ` Norman Hardy
2015-11-09  6:27     ` Florian Weimer
2015-11-09 13:27       ` Stefan Monnier
2015-11-09  8:10     ` Soegtrop, Michael
2015-11-09 10:00       ` Hendrik Boom [this message]
2015-11-09 10:17       ` Alain Frisch
2015-11-09 10:35         ` Andreas Rossberg
2015-11-09 12:28           ` Alain Frisch
2015-11-09 17:33           ` Alain Frisch
2015-11-09 18:09             ` Gabriel Scherer
2015-11-09 18:16               ` Andreas Rossberg
2015-11-09 21:12                 ` Gabriel Scherer
2015-11-09 22:06                   ` Alain Frisch
2015-11-09 22:27                   ` Andreas Rossberg
2015-11-09 22:57                     ` Jeremy Yallop
2015-11-10  0:11                   ` Hendrik Boom
2015-11-10  8:27                   ` Soegtrop, Michael
2015-11-10 10:26                     ` Romain Bardou
2015-11-10 10:44                       ` Alain Frisch
2015-11-10 10:55                         ` Romain Bardou
2015-11-10 13:17                           ` Alain Frisch
2015-11-10 13:41                             ` Romain Bardou
2015-11-10 14:01                               ` Alain Frisch
2015-11-13 15:36                           ` Romain Bardou
2015-11-10 11:17                         ` Soegtrop, Michael
2015-11-10 14:11                     ` Hendrik Boom
2015-11-10 14:40                       ` immanuel litzroth
2015-11-10 15:30                       ` Soegtrop, Michael
2015-11-10 17:28                         ` Gerd Stolpmann
2015-11-09 20:32               ` Alain Frisch

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