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
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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 let rec beta_expand test_equality_only metasenv subst context t arg =
47 let module S = CicSubstitution in
49 let rec aux metasenv subst n context t' =
52 fo_unif_subst test_equality_only subst context metasenv
53 (CicSubstitution.lift n arg) t'
55 subst,metasenv,C.Rel (1 + n)
58 | UnificationFailure _ ->
60 | C.Rel m -> subst,metasenv, if m <= n then C.Rel m else C.Rel (m+1)
61 | C.Var (uri,exp_named_subst) ->
62 let subst,metasenv,exp_named_subst' =
63 aux_exp_named_subst metasenv subst n context exp_named_subst
65 subst,metasenv,C.Var (uri,exp_named_subst')
68 let (_, t') = CicMetaSubst.lookup_subst i subst in
69 aux metasenv subst n context (CicSubstitution.lift_meta l t')
71 CicMetaSubst.SubstNotFound _ -> subst,metasenv,t)
73 | C.Implicit _ as t -> subst,metasenv,t
75 let subst,metasenv,te' = aux metasenv subst n context te in
76 let subst,metasenv,ty' = aux metasenv subst n context ty in
77 subst,metasenv,C.Cast (te', ty')
79 let subst,metasenv,s' = aux metasenv subst n context s in
80 let subst,metasenv,t' =
81 aux metasenv subst (n+1) ((Some (nn, C.Decl s))::context) t
83 subst,metasenv,C.Prod (nn, s', t')
84 | C.Lambda (nn,s,t) ->
85 let subst,metasenv,s' = aux metasenv subst n context s in
86 let subst,metasenv,t' =
87 aux metasenv subst (n+1) ((Some (nn, C.Decl s))::context) t
89 subst,metasenv,C.Lambda (nn, s', t')
91 let subst,metasenv,s' = aux metasenv subst n context s in
92 let subst,metasenv,t' =
93 aux metasenv subst (n+1) ((Some (nn, C.Def (s,None)))::context) t
95 subst,metasenv,C.LetIn (nn, s', t')
97 let subst,metasenv,revl' =
99 (fun (subst,metasenv,appl) t ->
100 let subst,metasenv,t' = aux metasenv subst n context t in
101 subst,metasenv,t'::appl
102 ) (subst,metasenv,[]) l
104 subst,metasenv,C.Appl (List.rev revl')
105 | C.Const (uri,exp_named_subst) ->
106 let subst,metasenv,exp_named_subst' =
107 aux_exp_named_subst metasenv subst n context exp_named_subst
109 subst,metasenv,C.Const (uri,exp_named_subst')
110 | C.MutInd (uri,i,exp_named_subst) ->
111 let subst,metasenv,exp_named_subst' =
112 aux_exp_named_subst metasenv subst n context exp_named_subst
114 subst,metasenv,C.MutInd (uri,i,exp_named_subst')
115 | C.MutConstruct (uri,i,j,exp_named_subst) ->
116 let subst,metasenv,exp_named_subst' =
117 aux_exp_named_subst metasenv subst n context exp_named_subst
119 subst,metasenv,C.MutConstruct (uri,i,j,exp_named_subst')
120 | C.MutCase (sp,i,outt,t,pl) ->
121 let subst,metasenv,outt' = aux metasenv subst n context outt in
122 let subst,metasenv,t' = aux metasenv subst n context t in
123 let subst,metasenv,revpl' =
125 (fun (subst,metasenv,pl) t ->
126 let subst,metasenv,t' = aux metasenv subst n context t in
127 subst,metasenv,t'::pl
128 ) (subst,metasenv,[]) pl
130 subst,metasenv,C.MutCase (sp,i,outt', t', List.rev revpl')
132 (*CSC: not implemented
133 let tylen = List.length fl in
136 (fun (name,i,ty,bo) -> (name, i, aux n ty, aux (n+tylen) bo))
139 C.Fix (i, substitutedfl)
140 *) subst,metasenv,CicMetaSubst.lift subst 1 t'
142 (*CSC: not implemented
143 let tylen = List.length fl in
146 (fun (name,ty,bo) -> (name, aux n ty, aux (n+tylen) bo))
149 C.CoFix (i, substitutedfl)
150 *) subst,metasenv,CicMetaSubst.lift subst 1 t'
152 and aux_exp_named_subst metasenv subst n context ens =
154 (fun (uri,t) (subst,metasenv,l) ->
155 let subst,metasenv,t' = aux metasenv subst n context t in
156 subst,metasenv,(uri,t')::l) ens (subst,metasenv,[])
158 let argty = type_of_aux' metasenv subst context arg in
160 FreshNamesGenerator.mk_fresh_name
161 metasenv context (Cic.Name "Heta") ~typ:argty
163 let subst,metasenv,t' = aux metasenv subst 0 context t in
164 subst, metasenv, C.Appl [C.Lambda (fresh_name,argty,t') ; arg]
166 and beta_expand_many test_equality_only metasenv subst context t =
168 (fun (subst,metasenv,t) arg ->
169 beta_expand test_equality_only metasenv subst context t arg
172 (* NUOVA UNIFICAZIONE *)
173 (* A substitution is a (int * Cic.term) list that associates a
174 metavariable i with its body.
175 A metaenv is a (int * Cic.term) list that associate a metavariable
177 fo_unif_new takes a metasenv, a context, two terms t1 and t2 and gives back
178 a new substitution which is _NOT_ unwinded. It must be unwinded before
181 and fo_unif_subst test_equality_only subst context metasenv t1 t2 =
182 let module C = Cic in
183 let module R = CicMetaSubst in
184 let module S = CicSubstitution in
186 (C.Meta (n,ln), C.Meta (m,lm)) when n=m ->
187 let ok,subst,metasenv =
190 (fun (b,subst,metasenv) t1 t2 ->
191 if b then true,subst,metasenv else
194 | _,None -> true,subst,metasenv
195 | Some t1', Some t2' ->
196 (* First possibility: restriction *)
197 (* Second possibility: unification *)
198 (* Third possibility: convertibility *)
199 if R.are_convertible subst context t1' t2' then
205 test_equality_only subst context metasenv t1' t2'
209 Not_found -> false,subst,metasenv)
210 ) (true,subst,metasenv) ln lm
212 Invalid_argument _ ->
213 raise (UnificationFailure (sprintf
214 "Error trying to unify %s with %s: the lengths of the two local contexts do not match." (CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2)))
219 raise (UnificationFailure (sprintf
220 "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."
221 (CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2)))
222 | (C.Meta (n,_), C.Meta (m,_)) when n>m ->
223 fo_unif_subst test_equality_only subst context metasenv t2 t1
225 | (t, C.Meta (n,l)) ->
228 C.Meta (n,_), C.Meta (m,_) when n < m -> false
229 | _, C.Meta _ -> false
232 let lower = fun x y -> if swap then y else x in
233 let upper = fun x y -> if swap then x else y in
234 let fo_unif_subst_ordered
235 test_equality_only subst context metasenv m1 m2 =
236 fo_unif_subst test_equality_only subst context metasenv
237 (lower m1 m2) (upper m1 m2)
241 let (_, oldt) = CicMetaSubst.lookup_subst n subst in
242 let lifted_oldt = S.lift_meta l oldt in
244 type_of_aux' metasenv subst context lifted_oldt
246 let tyt = type_of_aux' metasenv subst context t in
247 let (subst, metasenv) =
248 fo_unif_subst_ordered test_equality_only subst context metasenv
251 fo_unif_subst_ordered
252 test_equality_only subst context metasenv t lifted_oldt
253 with CicMetaSubst.SubstNotFound _ ->
254 (* First of all we unify the type of the meta with the type of the term *)
256 let (_,_,meta_type) = CicUtil.lookup_meta n metasenv in
258 let tyt = type_of_aux' metasenv subst context t in
261 subst context metasenv tyt (S.lift_meta l meta_type)
262 with AssertFailure _ ->
263 (* TODO huge hack!!!!
264 * we keep on unifying/refining in the hope that the problem will be
265 * eventually solved. In the meantime we're breaking a big invariant:
266 * the terms that we are unifying are no longer well typed in the
267 * current context (in the worst case we could even diverge)
270 prerr_endline "********* FROM NOW ON EVERY REASONABLE INVARIANT IS BROKEN.";
271 prerr_endline "********* PROCEED AT YOUR OWN RISK. AND GOOD LUCK." ;
275 let t',metasenv,subst =
277 CicMetaSubst.delift n subst context metasenv l t
279 (CicMetaSubst.MetaSubstFailure msg)-> raise(UnificationFailure msg)
280 | (CicMetaSubst.Uncertain msg) -> raise (Uncertain msg)
284 C.Sort (C.Type u) when not test_equality_only ->
285 let u' = CicUniv.fresh () in
286 let s = C.Sort (C.Type u') in
287 ignore (CicUniv.add_ge (upper u u') (lower u u')) ;
291 (* Unifying the types may have already instantiated n. Let's check *)
293 let (_, oldt) = CicMetaSubst.lookup_subst n subst in
294 let lifted_oldt = S.lift_meta l oldt in
295 fo_unif_subst_ordered
296 test_equality_only subst context metasenv t lifted_oldt
298 CicMetaSubst.SubstNotFound _ ->
299 let (_, context, _) = CicUtil.lookup_meta n metasenv in
300 let subst = (n, (context, t'')) :: subst in
302 (* CicMetaSubst.apply_subst_metasenv [n,(context, t'')] metasenv *)
303 CicMetaSubst.apply_subst_metasenv subst metasenv
306 (* (n,t'')::subst, metasenv *)
308 | (C.Var (uri1,exp_named_subst1),C.Var (uri2,exp_named_subst2))
309 | (C.Const (uri1,exp_named_subst1),C.Const (uri2,exp_named_subst2)) ->
310 if UriManager.eq uri1 uri2 then
311 fo_unif_subst_exp_named_subst test_equality_only subst context metasenv
312 exp_named_subst1 exp_named_subst2
314 raise (UnificationFailure (sprintf
315 "Can't unify %s with %s due to different constants"
316 (CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2)))
317 | C.MutInd (uri1,i1,exp_named_subst1),C.MutInd (uri2,i2,exp_named_subst2) ->
318 if UriManager.eq uri1 uri2 && i1 = i2 then
319 fo_unif_subst_exp_named_subst test_equality_only subst context metasenv
320 exp_named_subst1 exp_named_subst2
322 raise (UnificationFailure (sprintf
323 "Can't unify %s with %s due to different inductive principles"
324 (CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2)))
325 | C.MutConstruct (uri1,i1,j1,exp_named_subst1),
326 C.MutConstruct (uri2,i2,j2,exp_named_subst2) ->
327 if UriManager.eq uri1 uri2 && i1 = i2 && j1 = j2 then
328 fo_unif_subst_exp_named_subst test_equality_only subst context metasenv
329 exp_named_subst1 exp_named_subst2
331 raise (UnificationFailure (sprintf
332 "Can't unify %s with %s due to different inductive constructors"
333 (CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2)))
334 | (C.Implicit _, _) | (_, C.Implicit _) -> assert false
335 | (C.Cast (te,ty), t2) -> fo_unif_subst test_equality_only
336 subst context metasenv te t2
337 | (t1, C.Cast (te,ty)) -> fo_unif_subst test_equality_only
338 subst context metasenv t1 te
339 | (C.Prod (n1,s1,t1), C.Prod (_,s2,t2)) ->
340 (* TASSI: this is the only case in which we want == *)
341 let subst',metasenv' = fo_unif_subst true
342 subst context metasenv s1 s2 in
343 fo_unif_subst test_equality_only
344 subst' ((Some (n1,(C.Decl s1)))::context) metasenv' t1 t2
345 | (C.Lambda (n1,s1,t1), C.Lambda (_,s2,t2)) ->
346 (* TASSI: ask someone a reason for not putting true here *)
347 let subst',metasenv' = fo_unif_subst test_equality_only
348 subst context metasenv s1 s2 in
349 fo_unif_subst test_equality_only
350 subst' ((Some (n1,(C.Decl s1)))::context) metasenv' t1 t2
351 | (C.LetIn (_,s1,t1), t2)
352 | (t2, C.LetIn (_,s1,t1)) ->
354 test_equality_only subst context metasenv t2 (S.subst s1 t1)
355 | (C.Appl l1, C.Appl l2) ->
356 let subst,metasenv,t1',t2' =
358 C.Meta (i,_)::_, C.Meta (j,_)::_ when i = j ->
360 (* In the first two cases when we reach the next begin ... end
361 section useless work is done since, by construction, the list
362 of arguments will be equal.
364 | C.Meta (i,l)::args, _ ->
365 let subst,metasenv,t2' =
366 beta_expand_many test_equality_only metasenv subst context t2 args
368 subst,metasenv,t1,t2'
369 | _, C.Meta (i,l)::args ->
370 let subst,metasenv,t1' =
371 beta_expand_many test_equality_only metasenv subst context t1 args
373 subst,metasenv,t1',t2
379 C.Appl l1, C.Appl l2 ->
380 let lr1 = List.rev l1 in
381 let lr2 = List.rev l2 in
382 let rec fo_unif_l test_equality_only subst metasenv =
385 | _,[] -> assert false
387 fo_unif_subst test_equality_only subst context metasenv h1 h2
391 test_equality_only subst context metasenv h (C.Appl (List.rev l))
392 | ((h1::l1),(h2::l2)) ->
393 let subst', metasenv' =
394 fo_unif_subst test_equality_only subst context metasenv h1 h2
396 fo_unif_l test_equality_only subst' metasenv' (l1,l2)
398 fo_unif_l test_equality_only subst metasenv (lr1, lr2)
401 | (C.MutCase (_,_,outt1,t1',pl1), C.MutCase (_,_,outt2,t2',pl2))->
402 let subst', metasenv' =
403 fo_unif_subst test_equality_only subst context metasenv outt1 outt2 in
404 let subst'',metasenv'' =
405 fo_unif_subst test_equality_only subst' context metasenv' t1' t2' in
408 (function (subst,metasenv) ->
409 fo_unif_subst test_equality_only subst context metasenv
410 ) (subst'',metasenv'') pl1 pl2
412 Invalid_argument _ ->
413 raise (UnificationFailure (sprintf
414 "Error trying to unify %s with %s: the number of branches is not the same." (CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2))))
415 | (C.Rel _, _) | (_, C.Rel _) ->
419 raise (UnificationFailure (sprintf
420 "Can't unify %s with %s because they are not convertible"
421 (CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2)))
422 | (C.Sort _ ,_) | (_, C.Sort _)
423 | (C.Const _, _) | (_, C.Const _)
424 | (C.MutInd _, _) | (_, C.MutInd _)
425 | (C.MutConstruct _, _) | (_, C.MutConstruct _)
426 | (C.Fix _, _) | (_, C.Fix _)
427 | (C.CoFix _, _) | (_, C.CoFix _) ->
428 if t1 = t2 || R.are_convertible subst context t1 t2 then
431 raise (UnificationFailure (sprintf
432 "Can't unify %s with %s because they are not convertible"
433 (CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2)))
435 if R.are_convertible subst context t1 t2 then
438 raise (UnificationFailure (sprintf
439 "Can't unify %s with %s because they are not convertible"
440 (CicMetaSubst.ppterm subst t1) (CicMetaSubst.ppterm subst t2)))
442 and fo_unif_subst_exp_named_subst test_equality_only subst context metasenv
443 exp_named_subst1 exp_named_subst2
447 (fun (subst,metasenv) (uri1,t1) (uri2,t2) ->
449 fo_unif_subst test_equality_only subst context metasenv t1 t2
450 ) (subst,metasenv) exp_named_subst1 exp_named_subst2
452 Invalid_argument _ ->
457 UriManager.string_of_uri uri ^ " := " ^ (CicMetaSubst.ppterm subst t)
460 raise (UnificationFailure (sprintf
461 "Error trying to unify the two explicit named substitutions (local contexts) %s and %s: their lengths is different." (print_ens exp_named_subst1) (print_ens exp_named_subst2)))
463 (* A substitution is a (int * Cic.term) list that associates a *)
464 (* metavariable i with its body. *)
465 (* metasenv is of type Cic.metasenv *)
466 (* fo_unif takes a metasenv, a context, two terms t1 and t2 and gives back *)
467 (* a new substitution which is already unwinded and ready to be applied and *)
468 (* a new metasenv in which some hypothesis in the contexts of the *)
469 (* metavariables may have been restricted. *)
470 let fo_unif metasenv context t1 t2 =
471 fo_unif_subst false [] context metasenv t1 t2 ;;
473 let fo_unif_subst subst context metasenv t1 t2 =
475 sprintf "Unification error unifying %s of type %s with %s of type %s in context\n%s\nand metasenv\n%s\nbecause %s"
476 (CicMetaSubst.ppterm subst t1)
478 CicPp.ppterm (type_of_aux' metasenv subst context t1)
479 with _ -> "MALFORMED")
480 (CicMetaSubst.ppterm subst t2)
482 CicPp.ppterm (type_of_aux' metasenv subst context t2)
483 with _ -> "MALFORMED")
484 (CicMetaSubst.ppcontext subst context)
485 (CicMetaSubst.ppmetasenv metasenv subst) msg
488 fo_unif_subst false subst context metasenv t1 t2
490 | AssertFailure msg -> raise (AssertFailure (enrich_msg msg))
491 | UnificationFailure msg -> raise (UnificationFailure (enrich_msg msg))