Ocaml library implementing equivalence classes and partial orders

Ocaml library implementing equivalence classes and partial orders

[nari]

Hi,

I was wondering why there has been no Ocaml library implementation
for equivalence and partial order relations (at least over basic types)
just
as we have a 'Set' library over ordered types.

For example,
an equivalence class  module may export functions such as

type t
val create_equiv:  Set.t -> eqrelation.t -> t
val query_eqclass: t -> Set.elt -> Set.t
........

If the user specifies a set of elements and the user defines the
equivalence relation
on those elements, the function should return a datatype that
can be further queried for equivalence classes of individual elements.

Is there any specific reason why such a generic library may be
hard to implement? If not, are there any implementation issues we
need to be concerned about.
Thanx.


--
**************************************************************************
Narayanan Krishnamurthy (Nari)
ASP Advanced Tools and Methodology
Motorola SPS Architecture and Systems Platforms
Motorola Inc. Semiconductor Products Sector
7700 W. Parmer Lane, Austin, TX 78729

Loc/MD: TX32/PL30         _
email : nari@ibmoto.com /   \ email: Narayanan.Krishnamurthy@motorola.com
Ph    : (512) 996-4863  |O O| Fax : (512) 996-7432
************************| I |*********************************************
                        \ o /
                         ---

ocamlc command line suggested features

[thierry BRAVIER]

Dear ocamlers,

I have been trying labltk since ocaml-2.99 first with: labltklink
and now with: ocamlc -I$STDLIB/labltk labltk.cma foo.ml

* First, it made me think that an ocamlc -where option
(similar to that of camlp4) would be useful to get $STDLIB from ocamlc.

This would make it possible to use:
ocamlc -I `ocamlc -where`/labltk foo.ml

Remark 1: currently, I get $STDLIB from: (ocamlc -v  | some scritpt) which is
a pain,
Remark 2: I would rather not hard code STDLIB since I have several versions of
ocaml available.

* Second, since the documentation for labltk is short I often find myself
using the toplevel
just to check the type of say Tk.pack or Scale.configure.

Wouldn't it be nice if we could just say:
ocamlc -sig labltk.cma
to get the same output as with ocamlc -i
or maybe just use option -i itself as in:
ocamlc -i labltk.cma

That way it would not be necessary to ship libraries and .cmi files with
related .mli files

By the way, I am not a specialist of ocamlopt, what about this feature with
.cmxa files ?

Any comment ?

Cheers.

Thierry Bravier

Re: ocamlc command line suggested features

[Sven LUTHER]

On Thu, May 25, 2000 at 09:53:15AM +0200, thierry BRAVIER wrote:
> Dear ocamlers,
> 
> I have been trying labltk since ocaml-2.99 first with: labltklink
> and now with: ocamlc -I$STDLIB/labltk labltk.cma foo.ml
> 
> * First, it made me think that an ocamlc -where option
> (similar to that of camlp4) would be useful to get $STDLIB from ocamlc.
> 
> This would make it possible to use:
> ocamlc -I `ocamlc -where`/labltk foo.ml

you can already do it with this gmake definition :

  OCAMLDIR = $(shell $(CAMLC) -v | grep Standard | sed -e "s/^.*: //")

or by shell script :

  STDLIB=`ocamlc -v | grep Standard | sed -e "s/^.*: //"`

A better solution would be for ocamlc & co to search in the $STDLIB place as
well as in the current dir and absolute path, this way you could just write :

ocamlc -I labltk foo.ml

this would include $STDLIB/labltk.

Friendly,

Sven LUTHER

Re: ocamlc command line suggested features

[Jacques Garrigue]

From: "thierry BRAVIER" <thierry.bravier@dassault-aviation.fr>

> I have been trying labltk since ocaml-2.99 first with: labltklink
> and now with: ocamlc -I$STDLIB/labltk labltk.cma foo.ml
> 
> * First, it made me think that an ocamlc -where option
> (similar to that of camlp4) would be useful to get $STDLIB from ocamlc.
> 
> This would make it possible to use:
> ocamlc -I `ocamlc -where`/labltk foo.ml
> 
> Remark 1: currently, I get $STDLIB from: (ocamlc -v  | some scritpt) which is
> a pain,

Indeed a -where option would be useful, I also have lots of makefiles
using the same script as you, in particular for the install procedure.

But in this precise case, I would prefer the approach suggested by
Sven Luther: to have an abbreviated notation for paths under the
standard library directory.

For instance we could have
        ocamlc -I +labltk

Remark that now that we have the autolink mechanism, package path +
library name is all you need to link in a library.
(findlib is certainly more powerful, but it needs some form of
meta-information, which is better handled outside of the compiler)

> * Second, since the documentation for labltk is short I often find myself
> using the toplevel just to check the type of say Tk.pack or
> Scale.configure.

I should have made more evident in the manual that you _must_ use
ocamlbrowser (if labltk works, it works!). Then looking for function
types is trivial. (Don't forget to configure your path to include
the labltk directory.)

> Wouldn't it be nice if we could just say:
> ocamlc -sig labltk.cma

.cma files do not contain typing information, you have to look inside
.cmi files for that. And this is what ocamlbrowser does.

Cheers,

        Jacques
---------------------------------------------------------------------------
Jacques Garrigue      Kyoto University     garrigue at kurims.kyoto-u.ac.jp
		<A HREF=http://wwwfun.kurims.kyoto-u.ac.jp/~garrigue/>JG</A>