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Date: Wed, 30 Jul 2014 03:32:19 +0400
From: Peter Zotov <whitequark@whitequark.org>
In-Reply-To: <20140729214735.GA24140@delli7.univ-savoie.fr>
References: <20140729214735.GA24140@delli7.univ-savoie.fr>
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Subject: Re: [Caml-list] Writing preprocessor using compiler-libs

On 2014-07-30 01:47, Christophe Raffalli wrote:
> Hello,
> 
> There are a few examples and documentation on how to write syntax
> extensions without camlp4 using -ppx compiler flags.
> 
> However, I could not find an example of writing a preprocessor
> compatible with -pp only using compiler-libs and without camlp4 ?

The input format for -pp is plaintext; you can trivially use Lexer
and Parser from compiler-libs to get an OCaml AST.

The output format for -pp is either plaintext ('-pp cat' works), in
which case you can use Printast or Pprintast; or the same as for -ppx,
distinguished by the magic number, in which case you may use the
code from Ast_mapper[1] as an example.

   [1]: 
https://github.com/ocaml/ocaml/blob/68fe1ebd5a33636afd075419fa0362741f33f878/parsing/ast_mapper.ml#L652-L656

-- 
Peter Zotov