1 (* Copyright (C) 2000, HELM Team.
3 * This file is part of HELM, an Hypertextual, Electronic
4 * Library of Mathematics, developed at the Computer Science
5 * Department, University of Bologna, Italy.
7 * HELM is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2
10 * of the License, or (at your option) any later version.
12 * HELM is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with HELM; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
22 * For details, see the HELM World-Wide-Web page,
23 * http://cs.unibo.it/helm/.
28 exception UnificationFailure of string;;
29 exception Uncertain of string;;
30 exception AssertFailure of string;;
32 let debug_print = prerr_endline
34 let type_of_aux' metasenv subst context term =
36 CicMetaSubst.type_of_aux' metasenv subst context term
38 | CicMetaSubst.MetaSubstFailure msg ->
41 "Type checking error: %s in context\n%s\nand metasenv\n%s.\nException: %s.\nBroken invariant: unification must be invoked only on well typed terms"
42 (CicMetaSubst.ppterm subst term)
43 (CicMetaSubst.ppcontext subst context)
44 (CicMetaSubst.ppmetasenv metasenv subst) msg)))
46 (* NUOVA UNIFICAZIONE *)
47 (* A substitution is a (int * Cic.term) list that associates a
48 metavariable i with its body.
49 A metaenv is a (int * Cic.term) list that associate a metavariable
51 fo_unif_new takes a metasenv, a context, two terms t1 and t2 and gives back
52 a new substitution which is _NOT_ unwinded. It must be unwinded before
55 let rec fo_unif_subst subst context metasenv t1 t2 =
57 let module R = CicMetaSubst in
58 let module S = CicSubstitution in
60 (C.Meta (n,ln), C.Meta (m,lm)) when n=m ->
61 let ok,subst,metasenv =
63 (fun (b,subst,metasenv) t1 t2 ->
64 if b then true,subst,metasenv else
67 | _,None -> true,subst,metasenv
68 | Some t1', Some t2' ->
69 (* First possibility: restriction *)
70 (* Second possibility: unification *)
71 (* Third possibility: convertibility *)
72 if R.are_convertible subst context t1' t2' then
77 fo_unif_subst subst context metasenv t1' t2'
81 Not_found -> false,subst,metasenv)
82 ) (true,subst,metasenv) ln lm
87 raise (UnificationFailure (sprintf
88 "Error trying to unify %s with %s: the algorithm tried to check whether the two substitutions are convertible; if they are not, it tried to unify the two substitutions. No restriction was attempted."
89 (CicPp.ppterm t1) (CicPp.ppterm t2)))
90 | (C.Meta (n,l), C.Meta (m,_)) when n>m ->
91 fo_unif_subst subst context metasenv t2 t1
93 | (t, C.Meta (n,l)) ->
94 let subst'',metasenv' =
96 let oldt = (List.assoc n subst) in
97 let lifted_oldt = S.lift_meta l oldt in
98 fo_unif_subst subst context metasenv lifted_oldt t
100 let t',metasenv',subst' =
102 CicMetaSubst.delift n subst context metasenv l t
104 (CicMetaSubst.MetaSubstFailure msg)-> raise(UnificationFailure msg)
105 | (CicMetaSubst.Uncertain msg) -> raise (Uncertain msg)
107 (n, t')::subst', metasenv'
109 let (_,_,meta_type) = CicUtil.lookup_meta n metasenv' in
112 type_of_aux' metasenv' subst'' context t
114 fo_unif_subst subst'' context metasenv' (S.lift_meta l meta_type) tyt
115 with AssertFailure _ ->
116 (* TODO huge hack!!!!
117 * we keep on unifying/refining in the hope that the problem will be
118 * eventually solved. In the meantime we're breaking a big invariant:
119 * the terms that we are unifying are no longer well typed in the
120 * current context (in the worst case we could even diverge)
123 prerr_endline "********* FROM NOW ON EVERY REASONABLE INVARIANT IS BROKEN.";
124 prerr_endline "********* PROCEED AT YOUR OWN RISK. AND GOOD LUCK." ;
126 (subst'', metasenv'))
127 | (C.Var (uri1,exp_named_subst1),C.Var (uri2,exp_named_subst2))
128 | (C.Const (uri1,exp_named_subst1),C.Const (uri2,exp_named_subst2)) ->
129 if UriManager.eq uri1 uri2 then
130 fo_unif_subst_exp_named_subst subst context metasenv
131 exp_named_subst1 exp_named_subst2
133 raise (UnificationFailure (sprintf
134 "Can't unify %s with %s due to different constants"
135 (CicPp.ppterm t1) (CicPp.ppterm t2)))
136 | C.MutInd (uri1,i1,exp_named_subst1),C.MutInd (uri2,i2,exp_named_subst2) ->
137 if UriManager.eq uri1 uri2 && i1 = i2 then
138 fo_unif_subst_exp_named_subst subst context metasenv
139 exp_named_subst1 exp_named_subst2
141 raise (UnificationFailure (sprintf
142 "Can't unify %s with %s due to different inductive principles"
143 (CicPp.ppterm t1) (CicPp.ppterm t1)))
144 | C.MutConstruct (uri1,i1,j1,exp_named_subst1),
145 C.MutConstruct (uri2,i2,j2,exp_named_subst2) ->
146 if UriManager.eq uri1 uri2 && i1 = i2 && j1 = j2 then
147 fo_unif_subst_exp_named_subst subst context metasenv
148 exp_named_subst1 exp_named_subst2
150 raise (UnificationFailure (sprintf
151 "Can't unify %s with %s due to different inductive constructors"
152 (CicPp.ppterm t1) (CicPp.ppterm t1)))
153 | (C.Implicit _, _) | (_, C.Implicit _) -> assert false
154 | (C.Cast (te,ty), t2) -> fo_unif_subst subst context metasenv te t2
155 | (t1, C.Cast (te,ty)) -> fo_unif_subst subst context metasenv t1 te
156 | (C.Prod (n1,s1,t1), C.Prod (_,s2,t2)) ->
157 let subst',metasenv' = fo_unif_subst subst context metasenv s1 s2 in
158 fo_unif_subst subst' ((Some (n1,(C.Decl s1)))::context) metasenv' t1 t2
159 | (C.Lambda (n1,s1,t1), C.Lambda (_,s2,t2)) ->
160 let subst',metasenv' = fo_unif_subst subst context metasenv s1 s2 in
161 fo_unif_subst subst' ((Some (n1,(C.Decl s1)))::context) metasenv' t1 t2
162 | (C.LetIn (_,s1,t1), t2)
163 | (t2, C.LetIn (_,s1,t1)) ->
164 fo_unif_subst subst context metasenv t2 (S.subst s1 t1)
165 | (C.Appl l1, C.Appl l2) ->
166 let lr1 = List.rev l1 in
167 let lr2 = List.rev l2 in
168 let rec fo_unif_l subst metasenv =
171 | _,[] -> assert false
173 fo_unif_subst subst context metasenv h1 h2
176 fo_unif_subst subst context metasenv h (C.Appl (List.rev l))
177 | ((h1::l1),(h2::l2)) ->
178 let subst', metasenv' =
179 fo_unif_subst subst context metasenv h1 h2
181 fo_unif_l subst' metasenv' (l1,l2)
183 fo_unif_l subst metasenv (lr1, lr2)
184 | (C.MutCase (_,_,outt1,t1,pl1), C.MutCase (_,_,outt2,t2,pl2))->
185 let subst', metasenv' =
186 fo_unif_subst subst context metasenv outt1 outt2 in
187 let subst'',metasenv'' =
188 fo_unif_subst subst' context metasenv' t1 t2 in
190 (function (subst,metasenv) ->
191 fo_unif_subst subst context metasenv
192 ) (subst'',metasenv'') pl1 pl2
193 | (C.Rel _, _) | (_, C.Rel _)
194 | (C.Sort _ ,_) | (_, C.Sort _)
195 | (C.Const _, _) | (_, C.Const _)
196 | (C.MutInd _, _) | (_, C.MutInd _)
197 | (C.MutConstruct _, _) | (_, C.MutConstruct _)
198 | (C.Fix _, _) | (_, C.Fix _)
199 | (C.CoFix _, _) | (_, C.CoFix _) ->
200 if R.are_convertible subst context t1 t2 then
203 raise (UnificationFailure (sprintf
204 "Can't unify %s with %s because they are not convertible"
205 (CicPp.ppterm t1) (CicPp.ppterm t2)))
207 if R.are_convertible subst context t1 t2 then
210 raise (UnificationFailure (sprintf
211 "Can't unify %s with %s because they are not convertible"
212 (CicPp.ppterm t1) (CicPp.ppterm t2)))
214 and fo_unif_subst_exp_named_subst subst context metasenv
215 exp_named_subst1 exp_named_subst2
219 (fun (subst,metasenv) (uri1,t1) (uri2,t2) ->
221 fo_unif_subst subst context metasenv t1 t2
222 ) (subst,metasenv) exp_named_subst1 exp_named_subst2
225 let uri = UriManager.uri_of_string "cic:/dummy.var" in
226 debug_print ("@@@: " ^ CicPp.ppterm (Cic.Var (uri,exp_named_subst1)) ^
227 " <==> " ^ CicPp.ppterm (Cic.Var (uri,exp_named_subst2))) ; raise e
229 (* A substitution is a (int * Cic.term) list that associates a *)
230 (* metavariable i with its body. *)
231 (* metasenv is of type Cic.metasenv *)
232 (* fo_unif takes a metasenv, a context, two terms t1 and t2 and gives back *)
233 (* a new substitution which is already unwinded and ready to be applied and *)
234 (* a new metasenv in which some hypothesis in the contexts of the *)
235 (* metavariables may have been restricted. *)
236 let fo_unif metasenv context t1 t2 = fo_unif_subst [] context metasenv t1 t2 ;;
238 let fo_unif_subst subst context metasenv t1 t2 =
240 sprintf "Unification error unifying %s of type %s with %s of type %s in context\n%s\nand metasenv\n%s\nbecause %s"
241 (CicMetaSubst.ppterm subst t1)
243 CicPp.ppterm (type_of_aux' metasenv subst context t1)
244 with _ -> "MALFORMED")
245 (CicMetaSubst.ppterm subst t2)
247 CicPp.ppterm (type_of_aux' metasenv subst context t2)
248 with _ -> "MALFORMED")
249 (CicMetaSubst.ppcontext subst context)
250 (CicMetaSubst.ppmetasenv metasenv subst) msg
253 fo_unif_subst subst context metasenv t1 t2
255 | AssertFailure msg -> raise (AssertFailure (enrich_msg msg))
256 | UnificationFailure msg -> raise (UnificationFailure (enrich_msg msg))