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From: Stefan Monnier <monnier@iro.umontreal.ca>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Newbie comment on constructor syntax
Date: Mon, 09 Nov 2015 08:27:02 -0500
Message-ID: <jwvy4e7s41w.fsf-monnier+gmane.comp.lang.caml.inria@gnu.org> (raw)
In-Reply-To: <87y4e7662z.fsf@mid.deneb.enyo.de>

>> 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)

> With multiple constructors per type at least, this has a different
> in-memory representation: two objects (the constructed value and a
> tuple which the value references).

Of course, SML (being the less pragmatic brother) does not have this
"wart" and treats "X of int * int" the same as "X of (int * int)".

But this indeed comes at the cost of a less efficient representation.
You can try to "optimize" this away, but it becomes tricky when you
start using functors where type "t" is a parameter and you have
a constructor "X of t".

IOW, there were good pragmatic reasons to introduce this "wart".
This said I think Haskell shows that using a curried constructor
nicely circumvents the problem (of course it comes at the cost of not
being able to do the equivalent of "X of t", but that doesn't seem to
be much of a problem in practice, especially for Haskell where there
are no functors anyway).


        Stefan


  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 [this message]
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
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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