Camlp4 generate more than one (compiled) files?

Camlp4 generate more than one (compiled) files?

[Conglun Yao]

Dear all,

I'm just wondering is it possible to use camlp4 to generate more than
one compiled files.
Normally, camlp4 preprocesses a file and then pass it directly to
compiler (for *.cmo),  or its pretty-printer (for *.ml or other
'plain' file).

In my case, I want to extend the syntax, and write a file, then
preprocess (camlp4) it to generate two different *.cmo files, each one
could be executed separately.

Is it possible?

Thanks,
Conglun

Re: [Caml-list] Camlp4 generate more than one (compiled) files?

[Richard Jones]

On Fri, Oct 17, 2008 at 12:15:08PM +0100, Conglun Yao wrote:
> I'm just wondering is it possible to use camlp4 to generate more than
> one compiled files.
> Normally, camlp4 preprocesses a file and then pass it directly to
> compiler (for *.cmo),  or its pretty-printer (for *.ml or other
> 'plain' file).
> 
> In my case, I want to extend the syntax, and write a file, then
> preprocess (camlp4) it to generate two different *.cmo files, each one
> could be executed separately.
> 
> Is it possible?

Camlp4 extensions can open and write files normally.  However it
doesn't have access to crucial details of the 'OCaml environment' such
as the current search path for libraries, which means that it usually
cannot do anything sensible.

For example, I wanted to load another module/library from a camlp4
extension - but that sort of thing isn't possible as far as I can
tell.

I wrote a bit more about this issue here:

http://camltastic.blogspot.com/2008/05/persistent-matches-in-pabitmatch.html

Rich.

-- 
Richard Jones
Red Hat

Re: [Caml-list] Camlp4 generate more than one (compiled) files?

[Conglun Yao]

Rich,

Thanks for your reply.

What you mentioned in your blog:

In fact saving the AST into the cmo file is relatively simple: we just
turn it into a string (using Marshal) and write out the string as a
camlp4 substitution:
let bitmatch ext2sb = { ... }

becomes: let ext2sb = "<string containing marshalled representation of AST>"

If I understand correctly, the translated ext2sb would be kept in the
same cmo file(where the ext2sb is defined in the extended syntax),
rather than an additional (new) cmo file.

Currently I'm facing the problem that write a single file in extended
syntax, then camlp4 it into two different  cmo files.

e.g.   in extendFile.ml, we define a type t

type myextend t =  * type definition in my extended syntax *

then I want to translate it into:

extendFile.cmo:

   type t =  * standard ocaml type definition *

  module T  and some t-related functions

and another file newFile.cmo :

   some functions which doesn't rely on type t,
   like checking the existence of some files (name mentioned in type
t's definition)

I know it's possible to generate the latter functions and pretty-print
them into newFile.ml, but don't know how to get a compiled cmo file
directly.

Conglun




Conglun

On Fri, Oct 17, 2008 at 12:52 PM, Richard Jones <rich@annexia.org> wrote:

> Camlp4 extensions can open and write files normally.  However it
> doesn't have access to crucial details of the 'OCaml environment' such
> as the current search path for libraries, which means that it usually
> cannot do anything sensible.
>
> For example, I wanted to load another module/library from a camlp4
> extension - but that sort of thing isn't possible as far as I can
> tell.
>
> I wrote a bit more about this issue here:
>
> http://camltastic.blogspot.com/2008/05/persistent-matches-in-pabitmatch.html
>
> Rich.
>
> --
> Richard Jones
> Red Hat
>