Objective Label 2.04

Objective Label 2.04

[Jacques Garrigue]

This is my pleasure to announce

        The Objective Label Trilogy, version 2.04


As always the trilogy includes the Objective Label language, extending
Objective Caml with labeled and optional arguments, polymorphic
variants, and polymorphic methods; the LablTk GUI library; the
LablBrowser library browser.

There only few changes in this release:
  * the generation of olablc.opt and olablopt.opt for faster compilation
  * several bug fixes in the match compiler

You can obtain the trilogy from

        http://wwwfun.kurims.kyoto-u.ac.jp/soft/olabl/
        ftp://ftp.kurims.kyoto-u.ac.jp/pub/lang/olabl/

Notice that this is probably the last release of Objective Label,
since most of its functionality will be directly included in future
releases of Objective Caml.

However this release concerns very much people who:
   * have an important olabl code base. OCaml, even including most
     features, will not be fully compatible with the existing OLabl.
   * are using polymorphic methods. For technical reasons, this
     feature will probably not be included soon in OCaml.

------------------------------------------------------
Jacques Garrigue, visiting INRIA from Kyoto University
		          Jacques.Garrigue at inria.fr

Re: Objective Label 2.04

[Brian Rogoff]

On Thu, 2 Dec 1999, Jacques Garrigue wrote:
> By the way, I do not think that polymorphic methods are the _best_
> part of olabl. As its name goes, I believe that really labels are the
> nice part... But anybody may choose its pet feature.

Speaking of pet features, I noticed that the overloaded record label
feature of OLabl didn't make the cut. Can we expect that it will be  
included in a future OCaml, or is there a reason why we shouldn't?

-- Brian

Re: Objective Label 2.04

[Jacques Garrigue]

From: Juergen Pfitzenmaier <pfitzen@informatik.uni-tuebingen.de>

> Jacques Garrigue wrote:
> >    * are using polymorphic methods. For technical reasons, this
> >     feature will probably not be included soon in OCaml.
> 
> Why ? Polymorphic methods are the best part of OLabl. It should'nt
> be too hard to move code from OLabl to the OCaml distribution ?

The reason is that there was a major efficiency problem in olabl
typechecking, due to these methods. It can also produce huge .cmi
files. As long as these problems are not solved, it seems difficult to
include them in the production ocaml compiler.

Also, my experience with using them is contrasted. It is certainly a
nice feature, but not so easy to use: you have to give explicitly the
type when creating a method, and you need to know the type of the
object when using it.
They are not strictly needed, in that you can almost always write a
non-polymorphic method and a polymorphic function which calls it.

For all these reasons, inclusion of polymorphic methods into the
standard ocaml compiler is postponed until a more sarisfactory
solution is found.

As an intermediate solution, I may write a patch adding polymorphic
methods to the new ocaml compiler, as an experimental feature.

By the way, I do not think that polymorphic methods are the _best_
part of olabl. As its name goes, I believe that really labels are the
nice part... But anybody may choose its pet feature.

Regards,

Jacques Garrigue
------------------------------------------------------
Jacques Garrigue, visiting INRIA from Kyoto University
		          Jacques.Garrigue at inria.fr

Re: Objective Label 2.04

[Juergen Pfitzenmaier]

Jacques Garrigue wrote:
>    * are using polymorphic methods. For technical reasons, this
>     feature will probably not be included soon in OCaml.

Why ? Polymorphic methods are the best part of OLabl. It should'nt
be too hard to move code from OLabl to the OCaml distribution ?

pfitzen