Parsing

- Typage renforcé dans les grammaires (distinction des vars et des metavars)
- Disparition de SLAM au profit de ABSTRACT
- Paths primitifs dans les quotations (syntaxe concrète à base de .)
- Mise en place de identifier dès le type ast
- Protection de identifier contre les effets de bord via un String.copy
- Utilisation de module_ident (= identifier) dans les dir_path (au
  lieu de string)

Table des noms qualifiés

- Remplacement de la table de visibilité par une table qui ne cache
  plus les noms de modules et sections mais seulement les noms des
  constantes (e.g. Require A. ne cachera plus le contenu d'un éventuel
  module A déjà existant : seuls les noms de constructions de l'ancien
  A qui existent aussi dans le nouveau A seront cachés)
- Renoncement à la possibilité d'accéder les formes non déchargées des
  constantes définies à l'intérieur de sections et simplification
  connexes (suppression de END-SECTION, une seule table de noms qui ne
  survit pas au discharge)
- Utilisation de noms longs pour les modules, de noms qualifiés pour
  Require and co, tests de cohérence; pour être cohérent avec la non
  survie des tables de noms à la sortie des section, les require à
  l'intérieur d'une section eux aussi sont refaits à la fermeture de la
  section


git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@1889 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 597 insertions, 0 deletions

diff --git a/parsing/pretty.ml b/parsing/pretty.ml
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+++ b/parsing/pretty.ml
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+(***********************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team    *)
+(* <O___,, *        INRIA-Rocquencourt  &  LRI-CNRS-Orsay              *)
+(*   \VV/  *************************************************************)
+(*    //   *      This file is distributed under the terms of the      *)
+(*         *       GNU Lesser General Public License Version 2.1       *)
+(***********************************************************************)
+
+(* $Id$ *)
+
+open Pp
+open Util
+open Names
+open Term
+open Declarations
+open Inductive
+open Sign
+open Reduction
+open Environ
+open Instantiate
+open Library
+open Declare
+open Impargs
+open Libobject
+open Printer
+open Nametab
+
+let print_basename sp = pr_global (ConstRef sp)
+
+let print_closed_sections = ref false
+
+let print_typed_value_in_env env (trm,typ) =
+  [< prterm_env env trm ; 'fNL ;
+     'sTR "     : "; prtype_env env typ ; 'fNL >]
+
+let print_typed_value x = print_typed_value_in_env (Global.env ()) x
+
+let pkprinters = function
+  | FW -> (fprterm,fprterm_env)
+  | CCI -> (prterm,prterm_env)
+  | _ -> anomaly "pkprinters"
+			  		  
+let print_impl_args = function
+  | []  -> [<>]
+  | [i] -> [< 'sTR"Position ["; 'iNT i; 'sTR"] is implicit" >]
+  | l   -> 
+      [< 'sTR"Positions ["; 
+         prlist_with_sep (fun () -> [< 'sTR";" >]) (fun i -> [< 'iNT i >]) l;
+         'sTR"] are implicit" >]
+
+(* To be improved; the type should be used to provide the types in the
+   abstractions. This should be done recursively inside prterm, so that
+   the pretty-print of a proposition (P:(nat->nat)->Prop)(P [u]u)
+   synthesizes the type nat of the abstraction on u *)
+
+let print_named_def name body typ =
+  let pbody = prterm body in
+  let ptyp = prtype typ in
+  [< 'sTR "*** ["; 'sTR name ; 'sTR " ";
+     hOV 0 [< 'sTR ":="; 'bRK (1,2); pbody; 'sPC;
+	      'sTR ":"; 'bRK (1,2); ptyp >];
+	   'sTR "]"; 'fNL >]
+
+let print_named_assum name typ =
+  [< 'sTR "*** [" ; 'sTR name ; 'sTR " : "; prtype typ; 'sTR "]"; 'fNL >]
+
+let print_named_decl (id,c,typ) =
+  let s = string_of_id id in
+  match c with
+    | Some body -> print_named_def s body typ
+    | None -> print_named_assum s typ
+
+let assumptions_for_print lna =
+  List.fold_right (fun na env -> add_name na env) lna empty_names_context
+
+let implicit_args_id id l = 
+  if l = [] then 
+    [<>]
+  else 
+    [< 'sTR"For "; pr_id id; 'sTR": "; print_impl_args l ; 'fNL >]
+
+let implicit_args_msg sp mipv = 
+  [< prvecti
+       (fun i mip -> 
+	  let imps = inductive_implicits_list (sp,i) in
+          [< (implicit_args_id mip.mind_typename imps);
+             prvecti 
+	       (fun j idc ->
+		  let imps = constructor_implicits_list ((sp,i),succ j) in
+                  (implicit_args_id idc imps))
+               mip.mind_consnames 
+          >])
+       mipv >]
+
+let print_params env params =
+  if List.length params = 0 then 
+    [<>] 
+  else
+    [< 'sTR "["; pr_rel_context env params; 'sTR "]"; 'bRK(1,2) >]
+
+let print_constructors envpar names types =
+  let pc =
+    [< prvect_with_sep (fun () -> [<'bRK(1,0); 'sTR "| " >])
+         (fun (id,c) -> [< pr_id id; 'sTR " : "; prterm_env envpar c >])
+	 (array_map2 (fun n t -> (n,t)) names types) >]
+  in hV 0 [< 'sTR "  "; pc >] 
+
+let build_inductive sp tyi =
+  let ctxt = context_of_global_reference (IndRef (sp,tyi)) in
+  let ctxt = Array.of_list (instance_from_section_context ctxt) in
+  let mis = Global.lookup_mind_specif ((sp,tyi),ctxt) in
+  let params = mis_params_ctxt mis in
+  let args = extended_rel_list 0 params in
+  let indf = make_ind_family (mis,args) in
+  let arity = get_arity_type indf in
+  let cstrtypes = get_constructors_types indf in
+  let cstrnames = mis_consnames mis in
+  (IndRef (sp,tyi), params, arity, cstrnames, cstrtypes)
+
+let print_one_inductive sp tyi =
+  let (ref, params, arity, cstrnames, cstrtypes) = build_inductive sp tyi in
+  let env = Global.env () in
+  let envpar = push_rels params env in
+  (hOV 0
+     [< (hOV 0
+	   [< pr_global (IndRef (sp,tyi)) ; 'bRK(1,2); print_params env params;
+	      'sTR ": "; prterm_env envpar arity; 'sTR " :=" >]);
+	'bRK(1,2); print_constructors envpar cstrnames cstrtypes >]) 
+
+let print_mutual sp =
+  let mipv = (Global.lookup_mind sp).mind_packets in
+  if Array.length mipv = 1 then
+    let (ref, params, arity, cstrnames, cstrtypes) = build_inductive sp 0 in
+    let sfinite =
+      if mipv.(0).mind_finite then "Inductive " else "CoInductive " in
+    let env = Global.env () in
+    let envpar = push_rels params env in
+    (hOV 0 [< 
+       'sTR sfinite ; 
+      pr_global (IndRef (sp,0)); 'bRK(1,2);
+       print_params env params; 'bRK(1,5);
+       'sTR": "; prterm_env envpar arity; 'sTR" :=";
+       'bRK(0,4); print_constructors envpar cstrnames cstrtypes; 'fNL;
+       implicit_args_msg sp mipv  >] )
+  (* Mutual [co]inductive definitions *)
+  else
+    let _,(mipli,miplc) =
+      Array.fold_right
+        (fun mi (n,(li,lc)) ->
+           if mi.mind_finite then (n+1,(n::li,lc)) else (n+1,(li,n::lc)))
+        mipv (0,([],[])) 
+    in 
+    let strind =
+      if mipli = [] then [<>] 
+      else [< 'sTR "Inductive"; 'bRK(1,4);
+              (prlist_with_sep
+                 (fun () -> [< 'fNL; 'sTR"  with"; 'bRK(1,4) >])
+                 (print_one_inductive sp) mipli); 'fNL >]
+    and strcoind =
+      if miplc = [] then [<>] 
+      else [< 'sTR "CoInductive"; 'bRK(1,4);
+              (prlist_with_sep
+                 (fun () -> [<'fNL; 'sTR "  with"; 'bRK(1,4) >]) 
+                 (print_one_inductive sp) miplc); 'fNL >] 
+    in
+    (hV 0 [< 'sTR"Mutual " ; 
+             if mipv.(0).mind_finite then 
+	       [< strind; strcoind >] 
+             else 
+	       [<strcoind; strind>];
+             implicit_args_msg sp mipv >])
+
+(*
+  let env = Global.env () in
+  let evd = Evd.empty in
+  let {mind_packets=mipv} = mib in 
+  (* On suppose que tous les inductifs ont les même paramètres *)
+  let nparams = mipv.(0).mind_nparams in
+  let (lpars,_) = decomp_n_prod env evd nparams
+		    (body_of_type (mind_user_arity mipv.(0))) in
+  let arities = Array.map (fun mip -> (Name mip.mind_typename, None, mip.mind_nf_arity)) mipv in
+  let env_ar = push_rels lpars env in
+  let pr_constructor (id,c) =
+    [< pr_id id; 'sTR " : "; prterm_env env_ar c >] in
+  let print_constructors mis =
+    let (_,lC) = mis_type_mconstructs mis in
+    let lidC =
+      array_map2 (fun id c -> (id, snd (decomp_n_prod env evd nparams c)))
+	(mis_consnames mis) lC in
+    let plidC =
+      prvect_with_sep (fun () -> [<'bRK(0,0); 'sTR "| " >])
+        pr_constructor
+	lidC
+    in
+    hV 0 [< 'sTR "  "; plidC >] 
+  in
+  let params =
+    if nparams = 0 then 
+      [<>] 
+    else
+      [< 'sTR "["; pr_rel_context env lpars; 'sTR "]"; 'bRK(1,2) >] in
+  let print_oneind tyi =
+    let mis =
+      build_mis
+	((sp,tyi),
+	 Array.of_list (instance_from_section_context mib.mind_hyps))
+	mib in
+    let (_,arity) = decomp_n_prod env evd nparams
+		      (body_of_type (mis_user_arity mis)) in
+      (hOV 0
+         [< (hOV 0
+	       [< pr_global (IndRef (sp,tyi)) ; 'bRK(1,2); params;
+	          'sTR ": "; prterm_env env_ar arity; 'sTR " :=" >]);
+            'bRK(1,2); print_constructors mis >]) 
+  in 
+  let mis0 =
+    build_mis
+      ((sp,0),Array.of_list (instance_from_section_context mib.mind_hyps))
+      mib in
+  (* Case one [co]inductive *)
+  if Array.length mipv = 1 then
+    let (_,arity) = decomp_n_prod env evd nparams
+		      (body_of_type (mis_user_arity mis0)) in 
+    let sfinite = if mis_finite mis0 then "Inductive " else "CoInductive " in
+    (hOV 0 [< 'sTR sfinite ; pr_global (IndRef (sp,0));
+              if nparams = 0 then 
+		[<>] 
+              else 
+		[< 'sTR" ["; pr_rel_context env lpars; 'sTR "]">];
+              'bRK(1,5); 'sTR": "; prterm_env env_ar arity; 'sTR" :=";
+              'bRK(0,4); print_constructors mis0; 'fNL;
+              implicit_args_msg sp mipv  >] )
+  (* Mutual [co]inductive definitions *)
+  else
+    let _,(mipli,miplc) =
+      List.fold_left 
+        (fun (n,(li,lc)) mi ->
+           if mi.mind_finite then (n+1,(n::li,lc)) else (n+1,(li,n::lc)))
+        (0,([],[])) (Array.to_list mipv) 
+    in 
+    let strind =
+      if mipli = [] then [<>] 
+      else [< 'sTR "Inductive"; 'bRK(1,4);
+              (prlist_with_sep
+                 (fun () -> [< 'fNL; 'sTR"  with"; 'bRK(1,4) >])
+                 print_oneind
+                 (List.rev mipli)); 'fNL >]
+    and strcoind =
+      if miplc = [] then [<>] 
+      else [< 'sTR "CoInductive"; 'bRK(1,4);
+              (prlist_with_sep
+                 (fun () -> [<'fNL; 'sTR "  with"; 'bRK(1,4) >]) 
+                 print_oneind (List.rev miplc)); 'fNL >] 
+    in
+    (hV 0 [< 'sTR"Mutual " ; 
+             if mis_finite mis0 then 
+	       [< strind; strcoind >] 
+             else 
+	       [<strcoind; strind>];
+             implicit_args_msg sp mipv >])
+*)
+let print_section_variable sp =
+  let (d,_,_) = get_variable sp in
+  let l = implicits_of_var sp in
+  [< print_named_decl d; print_impl_args l; 'fNL >]
+
+let print_body = function
+  | Some c  -> prterm c
+  | None -> [< 'sTR"<no body>" >]
+
+let print_typed_body (val_0,typ) =
+  [< print_body val_0; 'fNL; 'sTR "     : "; prtype typ; 'fNL >]
+
+let print_constant with_values sep sp =
+  let cb = Global.lookup_constant sp in
+  if kind_of_path sp = CCI then
+    let val_0 = cb.const_body in
+    let typ = cb.const_type in
+    let impls = constant_implicits_list sp in
+    hOV 0 [< (match val_0 with 
+		| None -> 
+		    [< 'sTR"*** [ "; 
+		       print_basename sp;  
+		       'sTR " : "; 'cUT ; prtype typ ; 'sTR" ]"; 'fNL >]
+		| _ -> 
+		    [< print_basename sp; 
+		       'sTR sep; 'cUT ;
+		       if with_values then 
+			 print_typed_body (val_0,typ) 
+		       else 
+			 [< prtype typ ; 'fNL >] >]); 
+	     print_impl_args impls; 'fNL >]
+  else
+    hOV 0 [< 'sTR"Fw constant " ; 
+	     print_basename sp ; 'fNL>]
+
+let print_inductive sp =
+  if kind_of_path sp = CCI then
+    [< print_mutual sp; 'fNL >]
+  else
+    hOV 0 [< 'sTR"Fw inductive definition "; 
+	     print_basename sp; 'fNL >]
+
+let print_syntactic_def sep sp =
+  let id = basename sp in
+  let c = Syntax_def.search_syntactic_definition sp in 
+  [< 'sTR" Syntactif Definition "; pr_id id ; 'sTR sep; pr_rawterm c; 'fNL >]
+
+let print_leaf_entry with_values sep (sp,lobj) =
+  let tag = object_tag lobj in
+  match (sp,tag) with
+    | (_,"VARIABLE") ->
+	print_section_variable sp
+    | (_,("CONSTANT"|"PARAMETER")) ->
+	print_constant with_values sep sp
+    | (_,"INDUCTIVE") ->
+	print_inductive sp
+    | (_,"AUTOHINT") -> 
+	[< 'sTR" Hint Marker"; 'fNL >]
+    | (_,"GRAMMAR") -> 
+	[< 'sTR" Grammar Marker"; 'fNL >]
+    | (_,"SYNTAXCONSTANT") -> 
+	print_syntactic_def sep sp
+    | (_,"PPSYNTAX") -> 
+	[< 'sTR" Syntax Marker"; 'fNL >]
+    | (_,"TOKEN") -> 
+	[< 'sTR" Token Marker"; 'fNL >]
+    | (_,"CLASS") -> 
+	[< 'sTR" Class Marker"; 'fNL >]
+    | (_,"COERCION") -> 
+	[< 'sTR" Coercion Marker"; 'fNL >]
+    | (_,"REQUIRE") -> 
+	[< 'sTR" Require Marker"; 'fNL >]
+    | (_,"END-SECTION") -> [< >]
+    | (_,s) -> 
+	[< 'sTR(string_of_path sp); 'sTR" : ";
+           'sTR"Unrecognized object "; 'sTR s; 'fNL >]
+
+let rec print_library_entry with_values ent = 
+  let sep = if with_values then " = " else " : " in 
+  match ent with
+    | (sp,Lib.Leaf lobj) -> 
+	[< print_leaf_entry with_values sep (sp,lobj) >]
+    | (_,Lib.OpenedSection (str,_)) -> 
+        [< 'sTR(" >>>>>>> Section "^(string_of_id str)); 'fNL >]
+    | (sp,Lib.ClosedSection _) -> 
+        [< 'sTR" >>>>>>> Closed Section "; pr_id (basename sp);
+	   'fNL >]
+    | (_,Lib.Module dir) ->
+	[< 'sTR(" >>>>>>> Module " ^ (string_of_dirpath dir)); 'fNL >]
+    | (_,Lib.FrozenState _) ->
+	[< >]
+	
+and print_context with_values = 
+  let rec prec = function
+    | h::rest -> [< prec rest ; print_library_entry with_values h >]
+    | [] -> [< >]
+  in 
+  prec
+
+let print_full_context () = print_context true (Lib.contents_after None)
+
+let print_full_context_typ () = print_context false (Lib.contents_after None)
+
+(* For printing an inductive definition with
+   its constructors and elimination,
+   assume that the declaration of constructors and eliminations
+   follows the definition of the inductive type *)
+
+let list_filter_vec f vec = 
+  let rec frec n lf = 
+    if n < 0 then lf 
+    else if f vec.(n) then 
+      frec (n-1) (vec.(n)::lf)
+    else 
+      frec (n-1) lf
+  in 
+  frec (Array.length vec -1) []
+
+let read_sec_context qid =
+  let dir = Nametab.locate_section qid in
+  let rec get_cxt in_cxt = function
+    | ((sp,Lib.OpenedSection (_,_)) as hd)::rest ->
+	let dir' = make_dirpath (wd_of_sp sp) in
+        if dir = dir' then (hd::in_cxt) else get_cxt (hd::in_cxt) rest
+    | [] -> []
+    | hd::rest -> get_cxt (hd::in_cxt) rest 
+  in
+  let cxt = (Lib.contents_after None) in
+  List.rev (get_cxt [] cxt)
+
+let print_sec_context sec = print_context true (read_sec_context sec)
+
+let print_sec_context_typ sec = print_context false (read_sec_context sec)
+
+let print_judgment env {uj_val=trm;uj_type=typ} =
+  print_typed_value_in_env env (trm, typ)
+    
+let print_safe_judgment env j =
+  let trm = Safe_typing.j_val j in
+  let typ = Safe_typing.j_type j in
+  print_typed_value_in_env env (trm, typ)
+    
+let print_eval red_fun env {uj_val=trm;uj_type=typ} =
+  let ntrm = red_fun env Evd.empty trm in
+  [< 'sTR "     = "; print_judgment env {uj_val = ntrm; uj_type = typ} >]
+
+let print_name qid = 
+  try 
+    let sp = Nametab.locate_obj qid in
+    let (sp,lobj) = 
+      let (sp,entry) =
+	List.find (fun en -> (fst en) = sp) (Lib.contents_after None)
+      in
+      match entry with
+	| Lib.Leaf obj -> (sp,obj)
+	| _ -> raise Not_found
+    in
+    print_leaf_entry true " = " (sp,lobj)
+  with Not_found -> 
+  try 
+    match Nametab.locate qid with
+      | ConstRef sp -> print_constant true " = " sp
+      | IndRef (sp,_) -> print_inductive sp
+      | ConstructRef ((sp,_),_) -> print_inductive sp
+      | VarRef sp -> print_section_variable sp
+  with Not_found -> 
+  try  (* Var locale de but, pas var de section... donc pas d'implicits *)
+    let dir,str = repr_qualid qid in 
+    if dir <> [] then raise Not_found;
+    let (c,typ) = Global.lookup_named str in 
+    [< print_named_decl (str,c,typ) >]
+  with Not_found ->
+  try
+    let sp = Syntax_def.locate_syntactic_definition qid in
+    print_syntactic_def " = " sp
+  with Not_found ->
+    errorlabstrm "print_name"
+      [< pr_qualid qid; 'sPC; 'sTR "not a defined object" >]
+
+let print_opaque_name qid = 
+  let sigma = Evd.empty in
+  let env = Global.env () in
+  let sign = Global.named_context () in
+  try 
+    let x = global_qualified_reference qid in
+    match kind_of_term x with
+      | IsConst (sp,_ as cst) ->
+	  let cb = Global.lookup_constant sp in
+          if is_defined cb then
+	    print_constant true " = " sp
+          else 
+	    error "not a defined constant"
+      | IsMutInd ((sp,_),_) ->
+          print_mutual sp
+      | IsMutConstruct cstr -> 
+	  let ty = Typeops.type_of_constructor env sigma cstr in
+	  print_typed_value (x, ty)
+      | IsVar id ->
+          let (c,ty) = lookup_named id env in 
+	  print_named_decl (id,c,ty)
+      | _ -> 
+	  assert false
+  with Not_found -> 
+    errorlabstrm "print_opaque" [< pr_qualid qid; 'sPC; 'sTR "not declared" >]
+
+let print_local_context () =
+  let env = Lib.contents_after None in
+  let rec print_var_rec = function 
+    | [] -> [< >]
+    | (sp,Lib.Leaf lobj)::rest ->
+	if "VARIABLE" = object_tag lobj then
+          let (d,_,_) = get_variable sp in 
+	  [< print_var_rec rest;
+             print_named_decl d >]
+	else 
+	  print_var_rec rest
+    | _::rest -> print_var_rec rest
+
+  and print_last_const = function
+    | (sp,Lib.Leaf lobj)::rest -> 
+        (match object_tag lobj with
+           | "CONSTANT" | "PARAMETER" -> 
+               let {const_body=val_0;const_type=typ} = 
+		 Global.lookup_constant sp in
+               [< print_last_const rest;
+                  print_basename sp ;'sTR" = ";
+                  print_typed_body (val_0,typ) >]
+           | "INDUCTIVE" -> 
+               [< print_last_const rest;print_mutual sp; 'fNL >]
+           | "VARIABLE" ->  [< >]
+           | _          ->  print_last_const rest)
+    | _ -> [< >]
+  in 
+  [< print_var_rec env;  print_last_const env >]
+
+let fprint_var name typ =
+  [< 'sTR ("*** [" ^ name ^ " :"); fprtype typ; 'sTR "]"; 'fNL >]
+
+let fprint_judge {uj_val=trm;uj_type=typ} = 
+  [< fprterm trm; 'sTR" : " ; fprterm (body_of_type typ) >]
+
+let unfold_head_fconst = 
+  let rec unfrec k = match kind_of_term k with
+    | IsConst cst -> constant_value (Global.env ()) cst 
+    | IsLambda (na,t,b) -> mkLambda (na,t,unfrec b)
+    | IsApp (f,v) -> appvect (unfrec f,v)
+    | _ -> k
+  in 
+  unfrec
+
+(* for debug *)
+let inspect depth = 
+  let rec inspectrec n res env = 
+    if n=0 or env=[] then 
+      res
+    else 
+      inspectrec (n-1) (List.hd env::res) (List.tl env)
+  in 
+  let items = List.rev (inspectrec depth [] (Lib.contents_after None)) in
+  print_context false items
+
+
+(*************************************************************************)
+(* Pretty-printing functions coming from classops.ml                     *)
+
+open Classops
+
+let string_of_strength = function
+  | NotDeclare -> "(temp)"
+  | NeverDischarge -> "(global)"
+  | DischargeAt sp -> "(disch@"^(string_of_dirpath sp)
+
+let print_coercion_value v = prterm (get_coercion_value v)
+
+let print_index_coercion c = 
+  let _,v = coercion_info_from_index c in
+  print_coercion_value v
+
+let print_class i =
+  let cl,_ = class_info_from_index i in
+  [< 'sTR (string_of_class cl) >]
+  
+let print_path ((i,j),p) = 
+  [< 'sTR"["; 
+     prlist_with_sep (fun () -> [< 'sTR"; " >])
+       (fun c ->  print_index_coercion c) p;
+     'sTR"] : "; print_class i; 'sTR" >-> ";
+     print_class j >]
+
+let _ = Classops.install_path_printer print_path
+
+let print_graph () = 
+  [< prlist_with_sep pr_fnl print_path (inheritance_graph()) >]
+
+let print_classes () = 
+  [< prlist_with_sep pr_spc
+       (fun (_,(cl,x)) -> 
+          [< 'sTR (string_of_class cl)
+	       (*; 'sTR(string_of_strength x.cl_strength) *) >]) 
+       (classes()) >]
+
+let print_coercions () = 
+  [< prlist_with_sep pr_spc
+       (fun (_,(_,v)) -> [< print_coercion_value v >]) (coercions()) >]
+  
+let cl_of_id id = 
+  match string_of_id id with
+    | "FUNCLASS" -> CL_FUN
+    | "SORTCLASS" -> CL_SORT
+    | _ -> let v = Declare.global_reference CCI id in
+	   let cl,_ = constructor_at_head v in 
+	   cl
+
+let index_cl_of_id id =
+  try 
+    let cl = cl_of_id id in
+    let i,_ = class_info cl in 
+    i
+  with _ -> 
+    errorlabstrm "index_cl_of_id"
+      [< 'sTR(string_of_id id); 'sTR" is not a defined class" >]
+
+let print_path_between ids idt = 
+  let i = (index_cl_of_id ids) in
+  let j = (index_cl_of_id idt) in
+  let p = 
+    try 
+      lookup_path_between (i,j) 
+    with _ -> 
+      errorlabstrm "index_cl_of_id"
+        [< 'sTR"No path between ";'sTR(string_of_id ids); 
+	   'sTR" and ";'sTR(string_of_id ids) >]
+  in
+  print_path ((i,j),p)
+
+(*************************************************************************)