Camlp4 documentation

Camlp4 documentation

[Jon Harrop]

Are the constructions listed here:

  http://caml.inria.fr/pub/docs/manual-camlp4/manual010.html

valid for the new camlp4 as well?

For example, <:expr< ( $list:el$ ) >> to deconstruct a tuple.

If not, is there equivalent up-to-date documentation anywhere?

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

Re : [Caml-list] Camlp4 documentation

[Matthieu Wipliez]

Most of them are.

A tuple is represented as <:expr< ($e$) >> for instance, as can be seen on the Wiki page Abstract Syntax Tree:

    http://brion.inria.fr/gallium/index.php/Abstract_Syntax_Tree


Cheers,

Matthieu



----- Message d'origine ----
> De : Jon Harrop <jon@ffconsultancy.com>
> À : caml-list@inria.fr
> Envoyé le : Samedi, 23 Mai 2009, 14h24mn 45s
> Objet : [Caml-list] Camlp4 documentation
> 
> 
> Are the constructions listed here:
> 
>   http://caml.inria.fr/pub/docs/manual-camlp4/manual010.html
> 
> valid for the new camlp4 as well?
> 
> For example, <:expr< ( $list:el$ ) >> to deconstruct a tuple.
> 
> If not, is there equivalent up-to-date documentation anywhere?
> 
> -- 
> Dr Jon Harrop, Flying Frog Consultancy Ltd.
> http://www.ffconsultancy.com/?e
> 
> _______________________________________________
> Caml-list mailing list. Subscription management:
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Re: Re : [Caml-list] Camlp4 documentation

[Christophe TROESTLER]

On Sat, 23 May 2009 13:13:23 +0000, Matthieu Wipliez wrote:
> 
> A tuple is represented as <:expr< ($e$) >> 

Well, at the moment, the better is to complement the information on
the wiki with personal experiments in the toploop (and occasionally
read the Camlp4 sources).  For example, for the above assertion:

  #directory "+camlp4";;
  #load "dynlink.cma";;  (* OCaml >= 3.11.0 *)
  #load "camlp4of.cma";;
  open Camlp4.PreCast;;
  let _loc = Loc.ghost;;
  
  open Syntax;;

  # let f e = <:expr< ($e$) >>;;
  val f : 'a -> 'a = <fun>

With such a signature, you can imagine that f is just the identity
function and you can confirm it with a few experiments.  To match a
tuple, first look how they are represented:

  let e = <:expr< x,y,z >>;;
  val e : Camlp4.PreCast.Syntax.Ast.expr =
    Camlp4.PreCast.Syntax.Ast.ExTup (<abstr>,
     Camlp4.PreCast.Syntax.Ast.ExCom (<abstr>,
      Camlp4.PreCast.Syntax.Ast.ExId (<abstr>,
       Camlp4.PreCast.Syntax.Ast.IdLid (<abstr>, "x")),
      Camlp4.PreCast.Syntax.Ast.ExCom (<abstr>,
       Camlp4.PreCast.Syntax.Ast.ExId (<abstr>,
        Camlp4.PreCast.Syntax.Ast.IdLid (<abstr>, "y")),
       Camlp4.PreCast.Syntax.Ast.ExId (<abstr>,
        Camlp4.PreCast.Syntax.Ast.IdLid (<abstr>, "z")))))
  
Tuples are thus constructed with "ExTup" which is matched by $tup$ :

  # match e with <:expr< $tup:t$ >> -> t;;
  - : Camlp4.PreCast.Syntax.Ast.expr =
  Camlp4.PreCast.Syntax.Ast.ExCom (<abstr>,
   Camlp4.PreCast.Syntax.Ast.ExId (<abstr>,
    Camlp4.PreCast.Syntax.Ast.IdLid (<abstr>, "x")),
   Camlp4.PreCast.Syntax.Ast.ExCom (<abstr>,
    Camlp4.PreCast.Syntax.Ast.ExId (<abstr>,
     Camlp4.PreCast.Syntax.Ast.IdLid (<abstr>, "y")),
    Camlp4.PreCast.Syntax.Ast.ExId (<abstr>,
     Camlp4.PreCast.Syntax.Ast.IdLid (<abstr>, "z"))))

Then you probably want the individual components that are separated by
comas.  You can easily write your own function but looking at the
Camlp4 sources, you will find that it is already provided :

  # match e with <:expr< $tup:t$ >> -> Ast.list_of_expr t [];;
  - : Camlp4.PreCast.Syntax.Ast.expr list =
  [Camlp4.PreCast.Syntax.Ast.ExId (<abstr>,
    Camlp4.PreCast.Syntax.Ast.IdLid (<abstr>, "x"));
   Camlp4.PreCast.Syntax.Ast.ExId (<abstr>,
    Camlp4.PreCast.Syntax.Ast.IdLid (<abstr>, "y"));
   Camlp4.PreCast.Syntax.Ast.ExId (<abstr>,
    Camlp4.PreCast.Syntax.Ast.IdLid (<abstr>, "z"))]

Hope it helps,
C.

Re: [Caml-list] Camlp4 documentation

[Jon Harrop]

On Saturday 23 May 2009 18:37:21 Christophe TROESTLER wrote:
> Tuples are thus constructed with "ExTup" which is matched by $tup$ :

How did you determine that they are matched with $tup$?

> Hope it helps,

It does, thank you.

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

Re: [Caml-list] Camlp4 documentation

[Christophe TROESTLER]

On Sat, 23 May 2009 20:22:38 +0100, Jon Harrop wrote:
> 
> On Saturday 23 May 2009 18:37:21 Christophe TROESTLER wrote:
> > Tuples are thus constructed with "ExTup" which is matched by $tup$ :
> 
> How did you determine that they are matched with $tup$?

Frankly I can't remember.  Possibly in camlp4 sources or in a
discussion.

Regards,
C.

Re: [Caml-list] Camlp4 documentation

[Alex Cowie]

Alex Baretta wrote:

> Martin Jambon wrote:
>
>> On Thu, 17 Feb 2005, Christian Szegedy wrote:
>>
>>
>>> Feel free to write your CamlP4 extension ;)
>>
>>
>>
>> :-)
>> But there are few things to know/discover before starting.
>>
>> Is anyone interested in a kind of highly practical tutorial on
>> how to extend the syntax of OCaml with Camlp4?
>> I could possibly start writing one if there is enough demand.
>>
>>
>> Martin
>>
>
> Why yes! Yet, it's terribly sad that DdR chose to forcibly impose upon 
> the Camlp4 metaprogrammer to use the revised syntax. This is probably 
> the main obstacle, together with the relative lack of documentation, 
> to the diffusion of Camlp4, IMHO.
>
> Alex
>
For me, the use of revised syntax has been a disincentive to using 
Camlp4 metaprogramming.  I have always wondered whether a traditional 
syntax version of Camlp4 was technically feasible.  Any comments?

Alex Cowie

--
School of Computer and Information Science
University of South Australia

Re: [Caml-list] Camlp4 documentation

[Alex Baretta]

Martin Jambon wrote:
> On Thu, 17 Feb 2005, Christian Szegedy wrote:
> 
> 
>>Feel free to write your CamlP4 extension ;)
> 
> 
> :-)
> But there are few things to know/discover before starting.
> 
> Is anyone interested in a kind of highly practical tutorial on
> how to extend the syntax of OCaml with Camlp4?
> I could possibly start writing one if there is enough demand.
> 
> 
> Martin
> 

Why yes! Yet, it's terribly sad that DdR chose to forcibly impose upon 
the Camlp4 metaprogrammer to use the revised syntax. This is probably 
the main obstacle, together with the relative lack of documentation, to 
the diffusion of Camlp4, IMHO.

Alex

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