Camlp4 question

Camlp4 question

[Matt Gushee]

I had occasion today to look through the pa_r.ml, and noticed the
following (line 329 in OCaml 3.08.4):

  | "object"; cspo = OPT class_self_patt; cf = class_structure; "end" ->
      (* <:expr< object $opt:cspo$ $list:cf$ end >> *)
      MLast.ExObj loc cspo cf ]

So a quotation expander was created for objects as ordinary expressions,
but evidently there was something wrong with it. Anyone know what the
problem was?

--
Matt Gushee
Englewood, CO, USA

Re: [Caml-list] Camlp4 question

[Hendrik Tews]

Matt Gushee <matt@gushee.net> writes:

   I had occasion today to look through the pa_r.ml, and noticed the
   following (line 329 in OCaml 3.08.4):
   
     | "object"; cspo = OPT class_self_patt; cf = class_structure; "end" ->
         (* <:expr< object $opt:cspo$ $list:cf$ end >> *)
         MLast.ExObj loc cspo cf ]
   
   So a quotation expander was created for objects as ordinary expressions,
   but evidently there was something wrong with it. Anyone know what the
   problem was?
   
I believe the comment shows what the code should look like if
immediate objects would have been implemented in the quotation
expander q_MLast.ml. However, immediate objects are not yet in
the quotation expander, therefore the real code is what the
quoatation expander would have produced (if immediate objects had
been implemented).

Bye,

Hendrik

PS. Sorry Matt for posting separately to caml-list.

Camlp4 question

[Jacques Le Normand]

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Hello list,
how does one define type parameter syntax with camlp4?
right now I'm using:

  test:
    [[
       "mytype" ; options = OPT parameters  ; ident = a_LIDENT; "=" ; ctyp
-> (ident,atoms)
     ]];

  parameters:
    [
      ["(";params = comma_type_parameter;")" -> params]
    |
    [tp = type_parameter -> tp ]];

Is this the right way to do it or has parameters already been defined
elsewhere?

--Jacques L.

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camlp4 question

[Christophe Raffalli]

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I would like to produce an abbreviated command for

camlp4 mylexer.cmo mypa_o.cmo pa_extend.cmo q_MLast.cmo pr_dump.cmo\
  pa_bindlib.cmo

I tried to mimic the compilation of camlp4o:

ocamlc -I +camlp4 odyl.cma camlp4.cma mylexer.cmo mypa_o.cmo\
 pa_bindlib.cmo pr_dump.cmo odyl.cmo -o camlp4bo

But when I try to use ocamlp4bo, it produces no output ...

What am I doing wrong ?


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camlp4 question

[Christophe Raffalli]

I am writing a tool to facilitate the use of callback of camlfunction 
from C. I have a first prototype running for lablGlut, but I want to 
make it nicer using camlp4 (this extension should produce automatically 
the C wrapper for each callback, the user will only have to compile the 
produced C file).

The pb is that I need to retrieve information given in one module from 
another. The minimum I need to do is to search for the path given to 
ocamlc (the -I options) from camlp4 code, but I would prefer a better 
way, and I do not know how to retrive this PATH anyway.

Here is an example to illustrate what I need (the type 'a callback is a 
type to a C wrapper for a function of type 'a) :

-- file glut.ml, part of the lablGlut library --

...

let visibility_state_of_int = function
     0 ->  NOT_VISIBLE
   | 1 -> VISIBLE
   | _ -> raise (BadEnum "visibility_state")

REGISTER_CONVERSION visibility_state_of_int

external visibilityFunc :
   cb:(state:visibility_state_t->unit) callback->unit
    = "ml_glutVisibilityFunc"

...

-- file test.ml an example using lablGlut --

open Glut

...

let state_changed ~state =
   match value with
     NOT_VISIBLE -> printf "window not visible."; print_newline()
   | VISIBLE -> printf "window not visible."; print_newline()

MAKE_WRAPPER state_changed state_changed_cb
(* here I need to search for the convertion for the type 
visibility_state_of_int which was defined in glut.ml to make the
C wrapper state_changed_cb : (visibility_state_of_int -> unit) callback *)

let _ = Glut.visibilityFunc state_changed_cb

...

Can someone help ?

Re: camlp4 question

[Christophe Raffalli]

Yet another question ....

I was assuming you oculd ask the type of an expression in camlp4 to do 
an induction over it (the type) ....

I do not see that in the manual !

(you can only construct trees with camlp4, but you cannot match them ?)