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.\nException: %s.\nBroken invariant: unification must be invoked only on well typed terms"
42 (CicMetaSubst.ppterm subst term)
43 (CicMetaSubst.ppcontext subst context) msg)))
45 (* NUOVA UNIFICAZIONE *)
46 (* A substitution is a (int * Cic.term) list that associates a
47 metavariable i with its body.
48 A metaenv is a (int * Cic.term) list that associate a metavariable
50 fo_unif_new takes a metasenv, a context, two terms t1 and t2 and gives back
51 a new substitution which is _NOT_ unwinded. It must be unwinded before
54 let rec fo_unif_subst subst context metasenv t1 t2 =
56 let module R = CicMetaSubst in
57 let module S = CicSubstitution in
59 (C.Meta (n,ln), C.Meta (m,lm)) when n=m ->
60 let ok,subst,metasenv =
62 (fun (b,subst,metasenv) t1 t2 ->
63 if b then true,subst,metasenv else
66 | _,None -> true,subst,metasenv
67 | Some t1', Some t2' ->
68 (* First possibility: restriction *)
69 (* Second possibility: unification *)
70 (* Third possibility: convertibility *)
71 if R.are_convertible subst context t1' t2' then
76 fo_unif_subst subst context metasenv t1' t2'
80 Not_found -> false,subst,metasenv)
81 ) (true,subst,metasenv) ln lm
86 raise (UnificationFailure (sprintf
87 "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."
88 (CicPp.ppterm t1) (CicPp.ppterm t2)))
89 | (C.Meta (n,l), C.Meta (m,_)) when n>m ->
90 fo_unif_subst subst context metasenv t2 t1
92 | (t, C.Meta (n,l)) ->
93 let subst'',metasenv' =
95 let oldt = (List.assoc n subst) in
96 let lifted_oldt = S.lift_meta l oldt in
97 fo_unif_subst subst context metasenv lifted_oldt t
99 let t',metasenv',subst' =
101 CicMetaSubst.delift n subst context metasenv l t
103 (CicMetaSubst.MetaSubstFailure msg)-> raise(UnificationFailure msg)
104 | (CicMetaSubst.Uncertain msg) -> raise (Uncertain msg)
106 (n, t')::subst', metasenv'
108 let (_,_,meta_type) = CicUtil.lookup_meta n metasenv' in
111 type_of_aux' metasenv' subst'' context t
113 fo_unif_subst subst'' context metasenv' (S.lift_meta l meta_type) tyt
114 with AssertFailure _ ->
115 (* TODO huge hack!!!!
116 * we keep on unifying/refining in the hope that the problem will be
117 * eventually solved. In the meantime we're breaking a big invariant:
118 * the terms that we are unifying are no longer well typed in the
119 * current context (in the worst case we could even diverge)
122 prerr_endline "********* FROM NOW ON EVERY REASONABLE INVARIANT IS BROKEN.";
123 prerr_endline "********* PROCEED AT YOUR OWN RISK. AND GOOD LUCK." ;
125 (subst'', metasenv'))
126 | (C.Var (uri1,exp_named_subst1),C.Var (uri2,exp_named_subst2))
127 | (C.Const (uri1,exp_named_subst1),C.Const (uri2,exp_named_subst2)) ->
128 if UriManager.eq uri1 uri2 then
129 fo_unif_subst_exp_named_subst subst context metasenv
130 exp_named_subst1 exp_named_subst2
132 raise (UnificationFailure (sprintf
133 "Can't unify %s with %s due to different constants"
134 (CicPp.ppterm t1) (CicPp.ppterm t1)))
135 | C.MutInd (uri1,i1,exp_named_subst1),C.MutInd (uri2,i2,exp_named_subst2) ->
136 if UriManager.eq uri1 uri2 && i1 = i2 then
137 fo_unif_subst_exp_named_subst subst context metasenv
138 exp_named_subst1 exp_named_subst2
140 raise (UnificationFailure (sprintf
141 "Can't unify %s with %s due to different inductive principles"
142 (CicPp.ppterm t1) (CicPp.ppterm t1)))
143 | C.MutConstruct (uri1,i1,j1,exp_named_subst1),
144 C.MutConstruct (uri2,i2,j2,exp_named_subst2) ->
145 if UriManager.eq uri1 uri2 && i1 = i2 && j1 = j2 then
146 fo_unif_subst_exp_named_subst subst context metasenv
147 exp_named_subst1 exp_named_subst2
149 raise (UnificationFailure (sprintf
150 "Can't unify %s with %s due to different inductive constructors"
151 (CicPp.ppterm t1) (CicPp.ppterm t1)))
152 | (C.Implicit _, _) | (_, C.Implicit _) -> assert false
153 | (C.Cast (te,ty), t2) -> fo_unif_subst subst context metasenv te t2
154 | (t1, C.Cast (te,ty)) -> fo_unif_subst subst context metasenv t1 te
155 | (C.Prod (n1,s1,t1), C.Prod (_,s2,t2)) ->
156 let subst',metasenv' = fo_unif_subst subst context metasenv s1 s2 in
157 fo_unif_subst subst' ((Some (n1,(C.Decl s1)))::context) metasenv' t1 t2
158 | (C.Lambda (n1,s1,t1), C.Lambda (_,s2,t2)) ->
159 let subst',metasenv' = fo_unif_subst subst context metasenv s1 s2 in
160 fo_unif_subst subst' ((Some (n1,(C.Decl s1)))::context) metasenv' t1 t2
161 | (C.LetIn (_,s1,t1), t2)
162 | (t2, C.LetIn (_,s1,t1)) ->
163 fo_unif_subst subst context metasenv t2 (S.subst s1 t1)
164 | (C.Appl l1, C.Appl l2) ->
165 let lr1 = List.rev l1 in
166 let lr2 = List.rev l2 in
167 let rec fo_unif_l subst metasenv =
170 | _,[] -> assert false
172 fo_unif_subst subst context metasenv h1 h2
175 fo_unif_subst subst context metasenv h (C.Appl (List.rev l))
176 | ((h1::l1),(h2::l2)) ->
177 let subst', metasenv' =
178 fo_unif_subst subst context metasenv h1 h2
180 fo_unif_l subst' metasenv' (l1,l2)
182 fo_unif_l subst metasenv (lr1, lr2)
183 | (C.MutCase (_,_,outt1,t1,pl1), C.MutCase (_,_,outt2,t2,pl2))->
184 let subst', metasenv' =
185 fo_unif_subst subst context metasenv outt1 outt2 in
186 let subst'',metasenv'' =
187 fo_unif_subst subst' context metasenv' t1 t2 in
189 (function (subst,metasenv) ->
190 fo_unif_subst subst context metasenv
191 ) (subst'',metasenv'') pl1 pl2
192 | (C.Rel _, _) | (_, C.Rel _)
193 | (C.Sort _ ,_) | (_, C.Sort _)
194 | (C.Const _, _) | (_, C.Const _)
195 | (C.MutInd _, _) | (_, C.MutInd _)
196 | (C.MutConstruct _, _) | (_, C.MutConstruct _)
197 | (C.Fix _, _) | (_, C.Fix _)
198 | (C.CoFix _, _) | (_, C.CoFix _) ->
199 if R.are_convertible subst context t1 t2 then
202 raise (UnificationFailure (sprintf
203 "Can't unify %s with %s because they are not convertible"
204 (CicPp.ppterm t1) (CicPp.ppterm t2)))
206 if R.are_convertible subst context t1 t2 then
209 raise (UnificationFailure (sprintf
210 "Can't unify %s with %s because they are not convertible"
211 (CicPp.ppterm t1) (CicPp.ppterm t2)))
213 and fo_unif_subst_exp_named_subst subst context metasenv
214 exp_named_subst1 exp_named_subst2
218 (fun (subst,metasenv) (uri1,t1) (uri2,t2) ->
220 fo_unif_subst subst context metasenv t1 t2
221 ) (subst,metasenv) exp_named_subst1 exp_named_subst2
224 let uri = UriManager.uri_of_string "cic:/dummy.var" in
225 debug_print ("@@@: " ^ CicPp.ppterm (Cic.Var (uri,exp_named_subst1)) ^
226 " <==> " ^ CicPp.ppterm (Cic.Var (uri,exp_named_subst2))) ; raise e
228 (* A substitution is a (int * Cic.term) list that associates a *)
229 (* metavariable i with its body. *)
230 (* metasenv is of type Cic.metasenv *)
231 (* fo_unif takes a metasenv, a context, two terms t1 and t2 and gives back *)
232 (* a new substitution which is already unwinded and ready to be applied and *)
233 (* a new metasenv in which some hypothesis in the contexts of the *)
234 (* metavariables may have been restricted. *)
235 let fo_unif metasenv context t1 t2 = fo_unif_subst [] context metasenv t1 t2 ;;
237 let fo_unif_subst subst context metasenv t1 t2 =
239 sprintf "Unification error unifying %s of type %s with %s of type %s in context\n%s\nand metasenv\n%s\nbecause %s"
240 (CicMetaSubst.ppterm subst t1)
242 CicPp.ppterm (type_of_aux' metasenv subst context t1)
243 with _ -> "MALFORMED")
244 (CicMetaSubst.ppterm subst t2)
246 CicPp.ppterm (type_of_aux' metasenv subst context t2)
247 with _ -> "MALFORMED")
248 (CicMetaSubst.ppcontext subst context)
249 (CicMetaSubst.ppmetasenv metasenv subst) msg
252 fo_unif_subst subst context metasenv t1 t2
254 | AssertFailure msg -> raise (AssertFailure (enrich_msg msg))
255 | UnificationFailure msg -> raise (UnificationFailure (enrich_msg msg))