A C to OCaml helper ?

A C to OCaml helper ?

[Fabrice Marchant]

  Hi !

Please does it exist some tool that could do at least the very mechanical first parts of the translation of a C source to OCaml ?

  Thanks,

Fabrice

Re: [Caml-list] A C to OCaml helper ?

[Richard Jones]

On Wed, Mar 12, 2008 at 08:42:17PM +0100, Fabrice Marchant wrote:
> Please does it exist some tool that could do at least the very mechanical first parts of the translation of a C source to OCaml ?

camlidl (http://caml.inria.fr/pub/old_caml_site/camlidl/) is the
obvious choice.  It has a number of shortcomings though which I wrote
about in this posting:

http://tech.groups.yahoo.com/group/ocaml_beginners/message/9487

Rich.

-- 
Richard Jones
Red Hat

Re: [Caml-list] A C to OCaml helper ?

[Basile STARYNKEVITCH]

Fabrice Marchant wrote:
> Please does it exist some tool that could do at least the very mechanical first parts of the translation of a C source to OCaml ?

Why do you want to do that?

You could call most of your C routines from Ocaml.

And most importantly, the main interest of ocaml is the way of thinking 
it. When mastered, it is a language much more expressive & much more 
fun. And no mechanical translation would give you that....

If it is a homework, better to start thinking & coding in Ocaml, than to 
translate blindly C into Ocaml.

And a blind translation won't learn anything about Ocaml or functional 
programming.
-- 
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359
8, rue de la Faiencerie, 92340 Bourg La Reine, France
*** opinions {are only mines, sont seulement les miennes} ***

Re: [Caml-list] A C to OCaml helper ?

[Fabrice Marchant]

On Wed, 12 Mar 2008 22:03:51 +0100
Basile STARYNKEVITCH <basile@starynkevitch.net> wrote:

> Fabrice Marchant wrote:
> > Please does it exist some tool that could do at least the very mechanical first parts of the translation of a C source to OCaml ?
> 
> Why do you want to do that?

Why do I want a tool to do the _very mechanical parts_ of the job ?
  A simple example :
because I would be happy to get the comment brackets automatically translated ( and the C++ like C extension // too.)
  There are several such very automatic things like if( ) -> if then.

> You could call most of your C routines from Ocaml.
  Yes, but in the present case, I'm interesting in a full rewriting. This is precisely because I imagine to be able to rewrite the C ( game ) program a very different and terse way, that I undertake this task.

> And most importantly, the main interest of ocaml is the way of thinking 
> it.
Absolutely : that's the reason why I play to rewrite the C program an OCaml way.

 > When mastered, it is a language much more expressive & much more fun.
  Without daring to brag about 'mastering' the language,
I however declare to perfectly know this.

> And no mechanical translation would give you that....
  Obviously.

> If it is a homework, better to start thinking & coding in Ocaml, than to 
> translate blindly C into Ocaml.
> 
> And a blind translation won't learn anything about Ocaml or functional 
> programming.

  When I play chess, I always think the other player will give the best things and never suppose he has absurd ideas in mind...

  However, I remember you are the man who oriented me to OCaml and I'm very grateful of this, because OCaml programming is a real pleasure 

Best Regards,

Fabrice

http://caml.inria.fr/cgi-bin/hump.en.cgi?contrib=626
http://caml.inria.fr/cgi-bin/hump.en.cgi?contrib=627
http://caml.inria.fr/cgi-bin/hump.en.cgi?contrib=619

Re: [Caml-list] A C to OCaml helper ?

[Christopher L Conway]

You could try writing a CIL visitor that outputs an OCaml
transliteration (http://hal.cs.berkeley.edu/cil/). How well that would
work depends on what your C source code looks like.

Chris

On Wed, Mar 12, 2008 at 3:42 PM, Fabrice Marchant
<fabrice.marchant@orange.fr> wrote:
>   Hi !
>
>  Please does it exist some tool that could do at least the very mechanical first parts of the translation of a C source to OCaml ?
>
>   Thanks,
>
>  Fabrice
>
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>
>

Re: [Caml-list] A C to OCaml helper ?

[Jon Harrop]

On Wednesday 12 March 2008 19:42:17 Fabrice Marchant wrote:
>   Hi !
>
> Please does it exist some tool that could do at least the very mechanical
> first parts of the translation of a C source to OCaml ?

I do not believe such a tool exists but it would be a great educational 
exercise to try and write one. I can't think of any particularly difficult 
aspects. Maybe goto statements but they can be compiled to nested functions 
that call each other.

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com/products/?e

Re: [Caml-list] A C to OCaml helper ?

[Basile STARYNKEVITCH]

Fabrice Marchant wrote:
> On Wed, 12 Mar 2008 22:03:51 +0100
> Basile STARYNKEVITCH <basile@starynkevitch.net> wrote:
> 
>> Fabrice Marchant wrote:
>>> Please does it exist some tool that could do at least the very mechanical first parts of the translation of a C source to OCaml ?
>> Why do you want to do that?
> 
> Why do I want a tool to do the _very mechanical parts_ of the job ?
>   A simple example :
> because I would be happy to get the comment brackets automatically translated ( and the C++ like C extension // too.)
>   There are several such very automatic things like if( ) -> if then.
> 
>> You could call most of your C routines from Ocaml.
>   Yes, but in the present case, I'm interesting in a full rewriting. This is precisely because I imagine to be able to rewrite the C ( game ) program a very different and terse way, that I undertake this task.
> 
>> And most importantly, the main interest of ocaml is the way of thinking 
>> it.
> Absolutely : that's the reason why I play to rewrite the C program an OCaml way.

Then you have to rewrite it manually, because you have to re design your 
program differently (in a functional way). In particular, functional 
values are very common in Ocaml, and do not exist as such in C (a C 
pointer function is *not* a closure, you have to bring it some data); 
and combining both is done manually: callbacks, signal & slots [like in 
QT or GTK], etc...

Also, in Ocaml you frequently have tiny functions : just look at how 
easily you can sort an array of records of person's first & last names 
in Ocaml (it really fits in one or two lines), and how it become harder 
in C.

 >  However, I remember you are the man who oriented me to OCaml and I'm 
 > very grateful of this, because OCaml programming is a real pleasure

So you learnt that Ocaml programming paradigms are different from those 
in C.

I'm really not convinced that any automatic tool could bring you 
something valuable. Because tools do not help to re design (not only 
refactor or translate) programs.

And my advice is even to avoid doing any immediate translation by hand. 
Do not look often at your C code, but redesign your game (and your 
former experience in C game coding would help you). Perhaps this could 
be done incrementally, by keeping some routines in C (and calling them 
from Ocaml).

-- 
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
email: basile<at>starynkevitch<dot>net mobile: +33 6 8501 2359
8, rue de la Faiencerie, 92340 Bourg La Reine, France
*** opinions {are only mines, sont seulement les miennes} ***

Re: [Caml-list] A C to OCaml helper ?

[Kuba Ober]

On Thursday 13 March 2008, Basile STARYNKEVITCH wrote:
> Fabrice Marchant wrote:
> > On Wed, 12 Mar 2008 22:03:51 +0100
> >
> > Basile STARYNKEVITCH <basile@starynkevitch.net> wrote:
> >> Fabrice Marchant wrote:
> >>> Please does it exist some tool that could do at least the very
> >>> mechanical first parts of the translation of a C source to OCaml ?
> >>
> >> Why do you want to do that?
> >
> > Why do I want a tool to do the _very mechanical parts_ of the job ?
> >   A simple example :
> > because I would be happy to get the comment brackets automatically
> > translated ( and the C++ like C extension // too.) There are several such
> > very automatic things like if( ) -> if then.
> >
> >> You could call most of your C routines from Ocaml.
> >
> >   Yes, but in the present case, I'm interesting in a full rewriting. This
> > is precisely because I imagine to be able to rewrite the C ( game )
> > program a very different and terse way, that I undertake this task.
> >
> >> And most importantly, the main interest of ocaml is the way of thinking
> >> it.
> >
> > Absolutely : that's the reason why I play to rewrite the C program an
> > OCaml way.
>
> Then you have to rewrite it manually, because you have to re design your
> program differently (in a functional way). In particular, functional
> values are very common in Ocaml, and do not exist as such in C (a C
> pointer function is *not* a closure, you have to bring it some data);
> and combining both is done manually: callbacks, signal & slots [like in
> QT or GTK], etc...
>
> Also, in Ocaml you frequently have tiny functions : just look at how
> easily you can sort an array of records of person's first & last names
> in Ocaml (it really fits in one or two lines), and how it become harder
> in C.
>
>  >  However, I remember you are the man who oriented me to OCaml and I'm
>  > very grateful of this, because OCaml programming is a real pleasure
>
> So you learnt that Ocaml programming paradigms are different from those
> in C.
>
> I'm really not convinced that any automatic tool could bring you
> something valuable. Because tools do not help to re design (not only
> refactor or translate) programs.
>
> And my advice is even to avoid doing any immediate translation by hand.
> Do not look often at your C code, but redesign your game (and your
> former experience in C game coding would help you). Perhaps this could
> be done incrementally, by keeping some routines in C (and calling them
> from Ocaml).

I disagree somewhat. A good starting point is to have mechanically-translated
code that works, and then work on refactoring it to utilize what OCaml has to
offer.

In fact, C++ may provide much better translation results than C, since, if
properly written, the C++ sources will utilize higher-level primitives that
look better in OCaml. C is a really primitive language, by OCaml's 
standards ;)

Cheers, Kuba

Re: A C to OCaml helper ?

[Sylvain Le Gall]

On 17-03-2008, Kuba Ober <ober.14@osu.edu> wrote:
> On Thursday 13 March 2008, Basile STARYNKEVITCH wrote:
>> Fabrice Marchant wrote:
>> > On Wed, 12 Mar 2008 22:03:51 +0100
>> >
>> > Basile STARYNKEVITCH <basile@starynkevitch.net> wrote:
>> >> Fabrice Marchant wrote:
>> >>> Please does it exist some tool that could do at least the very
>> >>> mechanical first parts of the translation of a C source to OCaml ?
>> >>
>> >> Why do you want to do that?
>> >
> I disagree somewhat. A good starting point is to have mechanically-translated
> code that works, and then work on refactoring it to utilize what OCaml has to
> offer.
>
> In fact, C++ may provide much better translation results than C, since, if
> properly written, the C++ sources will utilize higher-level primitives that
> look better in OCaml. C is a really primitive language, by OCaml's 
> standards ;)
>

In my former work i have been able to see (and to participate) to some
kind of langage rewrite (PLI -> C++ for example). This is interesting,
because it "mechanically work" but it is far from being "humand
readable". 

Just to give you a couple of example:
* integer arithmetic are most of the time not what you think (i.e.
 COBOL/PLI doesn't have the same integer representation, C play with bit
 arithmetic, a lot of people like i++ on pointer...)
* float arithmetic is a nightmare (less than integer because you cannot
 do a lot of tricky stuff with it)
* with 99% of the tools you will find, you will loose your comments
* you will get a lot more lines than the initial program (because most
 of the tools do a local rewrite translating one token in langage SRC to
 many token in langage DST)

Results:
You will get a BIG program without any comments, containing tricky
behavior in one langage translated to buggy source code in OCaml (i let
you think about the pointer/pointer arithmetic problem).

BUT i am not saying this is not possible... It is always possible, you
will just get a pile of junk that works more or less... But don't think
you will be able to dig into a huge amount of code autogenerated without
comments and anything like that.

(just for fun: imagine all C macro expanded everywhere in your program
and then translated to ocaml -- take a look at stdlib.h to see how many
macros it uses ;-)

Conclusion of my former work: it works, but soure need to be near
destination language (e.g. COBOL MVS -> COBOL MicroFocus -- which is
already a nightmare).


IMHO, the real good way: define piece of code that will stay in C,
translate other parts, by hand, into OCaml, link both. When you feel
this or that part can be rewritten, remove the C stub and replace it.
And use the former C part for regression testing against the new OCaml
code.

Regards,
Sylvain Le Gall