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From: Alain Frisch <alain.frisch@lexifi.com>
To: Gabriel Scherer <gabriel.scherer@gmail.com>, Andreas Rossberg <rossberg@mpi-sws.org>
Cc: caml users <caml-list@inria.fr>
Subject: Re: [Caml-list] Newbie comment on constructor syntax
Date: Mon, 9 Nov 2015 23:06:53 +0100
Message-ID: <564118FD.5050804@lexifi.com> (raw)
In-Reply-To: <CAPFanBFze3PvO2JTSWByJUOyoYi-heb-pikQeHSsL_jKd3JecA@mail.gmail.com>

On 09/11/2015 22:11, Gabriel Scherer wrote:
> Yes, it is already problematic, and in fact I'm personally not
> completely convinced by this feature -- Alain it "reduces bad
> surprises for beginners", but I suspect that adding more magic in this
> place could not actually help that much -- at least the current
> semantic model is simple.

Just to illustrate that the confusion related to n-ary constructors is real:

http://stackoverflow.com/questions/3940345/defining-exceptions-with-tuple-as-argument
http://stackoverflow.com/questions/10306733/ocaml-constructor-unpacking
http://stackoverflow.com/questions/9774671/using-a-variant-type-constructor-with-just-one-tuple-value
http://stackoverflow.com/questions/14818866/int-int-vs-int-int-in-ocaml-sum-type


Now, it's not completely clear that the current proposal is enough to 
reduce significantly the confusion; one could argue that by hiding the 
difference between n-ary constructors and constructors with tuple 
arguments at the value level, one makes it harder for beginners to get 
the right mental model required to understand type inclusion ("type s = 
int * int;; type t = A of s" vs "type t = A of int * int").


-- Alain

  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
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 [this message]
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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