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Message-ID: <4A22132E.30505@ramenlabs.com>
Date: Sat, 30 May 2009 22:18:38 -0700
From: Dave Benjamin <dave@ramenlabs.com>
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To: Dario Teixeira <darioteixeira@yahoo.com>
Cc: Till Varoquaux <till.varoquaux@gmail.com>,
	caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Width subtyping
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X-Spam: no; 0.00; subtyping:01 escapes:01 ocaml:01 translating:01 syntax:01 camlp:01 syntax:01 translated:01 wrote:01 typing:01 caml-list:01 functions:01 functions:01 oop:01 benjamin:01 

Dario Teixeira wrote:
> Hi,
> 
>> There must be something that escapes me.... This seems to be an
>> example where ocaml objects really shine because of the structural
>> typing (i.e. an object is defined by the its structure):
> 
> You are right.  I was probably too fixated on the OOP way of doing this,
> translating record fields into object fields and the functions acting on
> records into object methods.  Your solution, where record fields become object
> methods and external functions act on objects that match a certain structure,
> does solve the inconveniences I mentioned before.  But objects are still
> a somewhat heavier solution, right?

Heavier in terms of efficiency, or syntax? If you mean the latter, I 
wonder if a camlp4 syntax extension might help ease the burden; perhaps 
something like:

   #{x=5; y=6}

could be translated to:

   object method x = 5 method y = 6 end

and then you could benefit from a lightweight syntax and still get the 
static type checking.

Dave