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Camlp4. print variable value to target source.
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Date: -- (:)
From: Сергей_ Плаксин <serp@s...>
Subject: Re: [Caml-list] Camlp4. print variable value to target source.
Thanks. It's what I need.

On Thu, 2008-09-11 at 14:56 +0200, Nicolas Pouillard wrote:
> Excerpts from SerP's message of Thu Sep 11 14:15:59 +0200 2008:
> > On Thu, 2008-09-11 at 13:00 +0100, Jeremy Yallop wrote:
> > > Quoting ?????? ??????? <serp@stork.ru>:
> > > > Exitst any way to do such things?
> > > >
> > > > ------
> > > >   let t = <:ctyp<int>> in
> > > >   <:str_item<let t = ?content of t here? >>
> > > 
> > > I think that you're looking for this:
> > > 
> > >      let t = <:expr< <:ctyp<int>> >> in
> > >      <:str_item<let t = $t$ >>
> > > 
> > > although I'm curious as to why.
> > > 
> > > Jeremy.
> > > 
> > 
> > The problem what t variable result of parsing
> > 
> > EXTEND Gram
> >   str_item:
> >     [
> >       [ "mtype" ; n = a_LIDENT ; "=" ; t = ctype ->
> >            <:expr<
> >               let f = <:expr<$t$>>
> >            >>
> >     ]
> > END
> > 
> > And result now is:
> > 
> > let f = t
> > 
> > But i need to:
> > 
> > let f = Ast.TyId (_loc, Ast.IdLid (_loc, "int"))
> 
> You the syntactic meta lifting (as in <:expr< <:ctyp< int >> >>) is not
> sufficient, you need to call the function that do this lifting.
> 
> #load "camlp4of.cma";;
> open Camlp4.PreCast;;
> module M = Ast.Meta.Make(Ast.Meta.MetaGhostLoc);;
> let ghost = Loc.ghost;;
> let t = <:ctyp@ghost< int >>;;
> M.Expr.meta_ctyp ghost t;;
> 
> Best regards,
> 
> PS: Tolevel output :)
> 
> - : Camlp4.PreCast.Ast.expr =
> Camlp4.PreCast.Ast.ExApp (<abstr>,
>      Camlp4.PreCast.Ast.ExApp (<abstr>,
>          Camlp4.PreCast.Ast.ExId (<abstr>,
>               Camlp4.PreCast.Ast.IdAcc (<abstr>,
>                     Camlp4.PreCast.Ast.IdUid (<abstr>, "Ast"),
>                         Camlp4.PreCast.Ast.IdUid (<abstr>, "TyId"))),
>            Camlp4.PreCast.Ast.ExId (<abstr>,
>                 Camlp4.PreCast.Ast.IdAcc (<abstr>,
>                       Camlp4.PreCast.Ast.IdUid (<abstr>, "Loc"),
>                           Camlp4.PreCast.Ast.IdLid (<abstr>, "ghost")))),
>       Camlp4.PreCast.Ast.ExApp (<abstr>,
>           Camlp4.PreCast.Ast.ExApp (<abstr>,
>                Camlp4.PreCast.Ast.ExId (<abstr>,
>                      Camlp4.PreCast.Ast.IdAcc (<abstr>,
>                             Camlp4.PreCast.Ast.IdUid (<abstr>, "Ast"),
>                                  Camlp4.PreCast.Ast.IdUid (<abstr>,
>                                    "IdLid"))),
>                   Camlp4.PreCast.Ast.ExId (<abstr>,
>                         Camlp4.PreCast.Ast.IdAcc (<abstr>,
>                                Camlp4.PreCast.Ast.IdUid (<abstr>, "Loc"),
>                                     Camlp4.PreCast.Ast.IdLid (<abstr>,
>                                       "ghost")))),
>             Camlp4.PreCast.Ast.ExStr (<abstr>, "int")))
>