diff --git a/Makefile.in b/Makefile.in
index 90d87c2a2f2f792ce5f851c2e71f6f4192ebb6be..f73926661a1c667d2537ae8c810040fb707f458c 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -177,7 +177,7 @@ LIB_DRIVER = prove_client call_provers driver_ast driver_parser driver_lexer dri
              parse_smtv2_model_parser parse_smtv2_model_lexer parse_smtv2_model
 
 LIB_MLW = ity expr dexpr pdecl eval_match vc pmodule \
-          pinterp pdriver
+          pinterp pdriver cprinter
 
 LIB_PARSER = ptree glob typing parser lexer
 
diff --git a/drivers/c.drv b/drivers/c.drv
new file mode 100644
index 0000000000000000000000000000000000000000..477e925b8597ddd1f69618266d8472b520bde91c
--- /dev/null
+++ b/drivers/c.drv
@@ -0,0 +1,3 @@
+
+
+printer "c"
diff --git a/src/mlw/cprinter.ml b/src/mlw/cprinter.ml
new file mode 100644
index 0000000000000000000000000000000000000000..ba932dfa0b82c3afab585bf5cfdb48774754603c
--- /dev/null
+++ b/src/mlw/cprinter.ml
@@ -0,0 +1,24 @@
+
+
+
+let fg ?fname m =
+  let n = m.Pmodule.mod_theory.Theory.th_name.Ident.id_string in
+  match fname with
+  | None -> n ^ ".c"
+  | Some f -> f ^ "__" ^ n ^ ".c"
+
+open Format
+
+let pr args ?old fmt m =
+  ignore(args);
+  ignore(old);
+  ignore(m);
+  fprintf fmt "#include <stdio.h>\n\
+\n\
+int main() {\n\
+  printf \"Extraction from WhyML to C not yet implemented\\n\";\n\
+  return 1;\n\
+}\n\
+"
+
+let () = Pdriver.register_printer "c" ~desc:"printer for C code" fg pr
diff --git a/src/mlw/pdriver.ml b/src/mlw/pdriver.ml
index 9bdeb6827bda001c0612c5ef560ffef76bfb386e..46b154555be4775a3d3750d02ad197ff801634e9 100644
--- a/src/mlw/pdriver.ml
+++ b/src/mlw/pdriver.ml
@@ -218,9 +218,11 @@ let load_driver env file extra_files =
 
 open Stdlib
 
+type filename_generator = ?fname:string -> Pmodule.pmodule -> string
+
 type printer = printer_args -> ?old:in_channel -> Pmodule.pmodule Pp.pp
 
-type reg_printer = Pp.formatted * printer
+type reg_printer = Pp.formatted * filename_generator * printer
 
 let printers : reg_printer Hstr.t = Hstr.create 17
 
@@ -228,18 +230,11 @@ exception KnownPrinter of string
 exception UnknownPrinter of string
 exception NoPrinter
 
-let register_printer ~desc s p =
+let register_printer ~desc s fg p =
   if Hstr.mem printers s then raise (KnownPrinter s);
-  Hstr.replace printers s (desc, p)
-
-let lookup_printer s =
-  try snd (Hstr.find printers s)
-  with Not_found -> raise (UnknownPrinter s)
-
-let list_printers () =
-  Hstr.fold (fun k (desc,_) acc -> (k,desc)::acc) printers []
+  Hstr.replace printers s (desc, fg, p)
 
-let extract_module ?old drv fmt m =
+let lookup_printer drv =
   let p = match drv.drv_printer with
     | None -> raise NoPrinter
     | Some p -> p
@@ -251,10 +246,20 @@ let extract_module ?old drv fmt m =
       blacklist   = drv.drv_blacklist;
       syntax      = drv.drv_syntax;
       converter   = drv.drv_converter;
-    } in
+    }
+  in
+  try
+    let (_,fg,p) = Hstr.find printers p in (fg,printer_args,p)
+  with Not_found -> raise (UnknownPrinter p)
+
+let list_printers () =
+  Hstr.fold (fun k (desc,_,_) acc -> (k,desc)::acc) printers []
+
+(*
+let extract_module ?old drv fmt m =
   let printer = lookup_printer p printer_args in
   Format.fprintf fmt "@[%a@]@?" (printer ?old) m
-
+ *)
 
 (* exception report *)
 
diff --git a/src/mlw/pdriver.mli b/src/mlw/pdriver.mli
index ba3c0fcf115b9e2e56f5f31b56970ba433bfe07d..bfe30858a5f970ef9cd585c9481402d29ae0c823 100644
--- a/src/mlw/pdriver.mli
+++ b/src/mlw/pdriver.mli
@@ -39,11 +39,15 @@ val load_driver : Env.env -> string -> string list -> driver
 
 type printer = printer_args -> ?old:in_channel -> Pmodule.pmodule Pp.pp
 
-val register_printer : desc:Pp.formatted -> string -> printer -> unit
+type filename_generator = ?fname:string -> Pmodule.pmodule -> string
 
-val lookup_printer : string -> printer
+val register_printer : desc:Pp.formatted -> string -> filename_generator -> printer -> unit
+
+val lookup_printer : driver -> filename_generator * printer_args * printer
 
 val list_printers : unit -> (string * Pp.formatted) list
 
+(*
 val extract_module : ?old:in_channel ->
    driver -> Format.formatter -> Pmodule.pmodule -> unit
+ *)
diff --git a/src/tools/why3extract.ml b/src/tools/why3extract.ml
index 2a6cdc1af7dd1e5d0b28633275f3fdaf17c2d23d..276a8d54e584fad510391912b5df568cc12e42d2 100644
--- a/src/tools/why3extract.ml
+++ b/src/tools/why3extract.ml
@@ -12,7 +12,7 @@
 open Format
 open Why3
 open Stdlib
-open Theory
+open Pmodule
 
 let usage_msg = sprintf
   "Usage: %s [options] -D <driver> -o <dir> [[file|-] [-T <theory>]...]..."
@@ -27,6 +27,7 @@ let add_opt_file x =
   Queue.push (Some x, tlist) opt_queue;
   opt_input := Some tlist
 
+(* TODO : rename theory into module, -T into -M *)
 let add_opt_theory x =
   let l = Strings.split '.' x in
   let p, t = match List.rev l with
@@ -99,8 +100,9 @@ let opt_driver =
     eprintf "%a@." Exn_printer.exn_printer e;
     exit 1
 
-let extract_to ?fname:string m =
-  let file = Filename.concat opt_output (assert false (*Mlw_ocaml.extract_filename ?fname th *)) in
+let extract_to ?fname m =
+  let (fg,pargs,pr) = Pdriver.lookup_printer opt_driver in
+  let file = Filename.concat opt_output (fg ?fname m) in
   let old =
     if Sys.file_exists file then begin
       let backup = file ^ ".bak" in
@@ -109,41 +111,36 @@ let extract_to ?fname:string m =
     end else None in
   let cout = open_out file in
   let fmt = formatter_of_out_channel cout in
-  let tname = m.Pmodule.mod_theory.th_name.Ident.id_string in
+  let tname = m.mod_theory.Theory.th_name.Ident.id_string in
   Debug.dprintf Pdriver.debug "extract module %s to file %s@." tname file;
-  Pdriver.extract_module ?old opt_driver fmt m;
+  pr ?old pargs fmt m;
   close_out cout
 
 let extract_to =
   let visited = Ident.Hid.create 17 in
   fun ?fname m ->
-    let name = m.Pmodule.mod_theory.Theory.th_name in
+    let name = m.mod_theory.Theory.th_name in
     if not (Ident.Hid.mem visited name) then begin
       Ident.Hid.add visited name ();
       extract_to ?fname m
     end
 
-let use_iter f th =
-  List.iter (fun d -> match d.td_node with Use t -> f t | _ -> ()) th.th_decls
+let rec use_iter f l =
+  List.iter (function Uuse t -> f t | Uscope (_,_,l) -> use_iter f l | _ -> ()) l
 
-let (* rec *) do_extract_module ?fname m =
-  extract_to ?fname m;
-  assert false
-(* TODO: extract also used modules ? Or let each extraction function decide what "used" parts should be extracted ?
-
-  let extract_use th' =
-    let fname = if th'.th_path = [] then fname else None in
-    match
-      try Some (Mlw_module.restore_module th') with Not_found -> None
-    with
-      | Some m' -> do_extract_module ?fname m'
-      | None    -> do_extract_theory ?fname th' in
-  use_iter extract_use m.Mlw_module.mod_theory
- *)
+let rec do_extract_module ?fname m =
+  let extract_use m' =
+    let fname =
+      if m'.mod_theory.Theory.th_path = [] then fname else None
+    in
+    do_extract_module ?fname m'
+  in
+  use_iter extract_use m.mod_units;
+  extract_to ?fname m
 
 let do_global_extract (_,p,t) =
   let env = opt_driver.Pdriver.drv_env in
-  let m = Pmodule.read_module env p t in
+  let m = read_module env p t in
   do_extract_module m
 
 
@@ -158,7 +155,7 @@ let do_local_extract fname cin tlist =
   let env = opt_driver.Pdriver.drv_env in
   let format = !opt_parser in
   let mm =
-    Env.read_channel ?format Pmodule.mlw_language env fname cin in
+    Env.read_channel ?format mlw_language env fname cin in
   if Queue.is_empty tlist then
     let do_m _ m = do_extract_module ~fname m in
     Mstr.iter do_m mm