[Caml-list] Genlex - and which parser?

[Caml-list] Genlex - and which parser?

[Oliver Bandel]

Hello,

I recently (today) experimented with the Genlex-module.
It seems to be very very easy to lex code.

(But some things are predefined, what has advantages and
 disadvantages, I think, but doesn't matter here.)

Which parser can be used together with Genlex?
Is it ocamlyacc? Or others?

Or do I have to write most code for parsing by my own?

Are there any examples in using the Genlex-module?

Seems to be the easiest lexer I found.
If there would be a Genpare-module, this would be
the easiest way for writing little-language's parsers.

So, any hints are welcome.


Ciao,
   Oliver


-- 
           IT nach Hause telefonieren...

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Re: [Caml-list] Genlex - and which parser?

[Remi VANICAT]

Oliver Bandel <oliver@first.in-berlin.de> writes:

> Hello,
>
> I recently (today) experimented with the Genlex-module.
> It seems to be very very easy to lex code.
>
> (But some things are predefined, what has advantages and
>  disadvantages, I think, but doesn't matter here.)
>
> Which parser can be used together with Genlex?
> Is it ocamlyacc? Or others?

ocamlyacc goes with ocamllex. parser that goes with Genlex are stream
parser, describe in chapter 2 of the Camlp4 reference manual and
chapter 2 of the Camlp4 tutorial

-- 
Rémi Vanicat
vanicat@labri.u-bordeaux.fr
http://dept-info.labri.u-bordeaux.fr/~vanicat
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Re: [Caml-list] Genlex - and which parser?

[Oliver Bandel]

Hello Rémi,


On Mon, 2 Sep 2002, Remi VANICAT wrote:

> Oliver Bandel <oliver@first.in-berlin.de> writes:
[...]
> > Which parser can be used together with Genlex?
> > Is it ocamlyacc? Or others?
> 
> ocamlyacc goes with ocamllex. parser that goes with Genlex are stream
> parser, describe in chapter 2 of the Camlp4 reference manual and
> chapter 2 of the Camlp4 tutorial

Hmhhh in the campl4-tutorial/-reference they explain an other
Lexer (Plexer). I think it's similar.
Will Genlex not be used? Or is Plexer based on Genlex?

Any way, thanks for your hint.



Some additional words:

In the camlp4-tutorial there is an example for programming a
simple calculator.
I didn't expect to get a working solution/example on page 9
of the tutorial.
That's great!

I have looked for such tools for many years and now I have found it. :)

Again, as I said about OCaml, I can say about Camlp4, that
it's a great piece of work, what the developpers/researchers
have done in providing such a great language and tools.

If I think about how to write such stuff with lex/yacc
in C, and then look at the power of Ocaml wow, then I more
and more see that writing C (and it's followers) are the middle-
ages of programming.

Ciao,
   Oliver

P.S.: I think it's now time to write DSLs. :)


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Re: [Caml-list] Genlex - and which parser?

[Daniel de Rauglaudre]

Hi,

On Mon, Sep 02, 2002 at 02:35:32PM +0200, Oliver Bandel wrote:

> Hmhhh in the campl4-tutorial/-reference they explain an other
> Lexer (Plexer). I think it's similar.
> Will Genlex not be used? Or is Plexer based on Genlex?

No: the lexer Plexer of Camlp4 does not use Genlex. Genlex is for
simple lexers and does not suit for lexing OCaml and the extensions
that Camlp4 need (e.g. quotations).

-- 
Daniel de RAUGLAUDRE
daniel.de_rauglaudre@inria.fr
http://cristal.inria.fr/~ddr/
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Re: [Caml-list] Genlex - and which parser?

[Remi VANICAT]

Oliver Bandel <oliver@first.in-berlin.de> writes:

> Hello Rémi,
>
>
> On Mon, 2 Sep 2002, Remi VANICAT wrote:
>
>> Oliver Bandel <oliver@first.in-berlin.de> writes:
> [...]
>> > Which parser can be used together with Genlex?
>> > Is it ocamlyacc? Or others?
>> 
>> ocamlyacc goes with ocamllex. parser that goes with Genlex are stream
>> parser, describe in chapter 2 of the Camlp4 reference manual and
>> chapter 2 of the Camlp4 tutorial
>
> Hmhhh in the campl4-tutorial/-reference they explain an other
> Lexer (Plexer). I think it's similar.
> Will Genlex not be used? Or is Plexer based on Genlex?
>
> Any way, thanks for your hint.

Well, there is to type of parser that you can read about in the camlp4
documentation :
those of the chapter 2 (Streams and parsers) which correspond to the
Genlex lexer, and those of the Camlp4 Grammar module, which use
Plexer. 

Here an example of the Stream parser :

open Genlex;;

let lexer = make_lexer ["+"; "-"; "("; ")"];;

let rec simple_calc = parser
   | [< v = simple_value ; rest >] -> 
          simple_calc_rest v rest
and simple_value = parser
   | [< 'Int i >] -> i
   | [< 'Kwd "("; v = simple_calc; 'Kwd ")" >] -> v
and simple_calc_rest v1 = parser
   | [< 'Kwd "+"; v2 = simple_calc >] -> v1 + v2
   | [< 'Kwd "-"; v2 = simple_calc >] -> v1 - v2
   | [< >] -> v1;;

let make_calc () =
  let l = read_line () in
  let st = Stream.of_string l in
  let le = lexer st in
  simple_calc le;;

(notice that this parser is buggy : it evaluated 3 - 1 + 3 as -1 when
it should answer 5).

-- 
Rémi Vanicat
vanicat@labri.u-bordeaux.fr
http://dept-info.labri.u-bordeaux.fr/~vanicat
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