1 (* Copyright (C) 2002, 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/.
26 open ProofEngineHelpers
29 exception NotAnInductiveTypeToEliminate
30 exception NotTheRightEliminatorShape
31 exception NoHypothesesFound
32 exception WrongUriToVariable of string
34 (* lambda_abstract newmeta ty *)
35 (* returns a triple [bo],[context],[ty'] where *)
36 (* [ty] = Pi/LetIn [context].[ty'] ([context] is a vector!) *)
37 (* and [bo] = Lambda/LetIn [context].(Meta [newmeta]) *)
38 (* So, lambda_abstract is the core of the implementation of *)
39 (* the Intros tactic. *)
40 let lambda_abstract metasenv context newmeta ty mk_fresh_name =
42 let rec collect_context context =
44 C.Cast (te,_) -> collect_context context te
46 let n' = mk_fresh_name metasenv context n ~typ:s in
47 let (context',ty,bo) =
48 collect_context ((Some (n',(C.Decl s)))::context) t
50 (context',ty,C.Lambda(n',s,bo))
52 let (context',ty,bo) =
53 collect_context ((Some (n,(C.Def (s,None))))::context) t
55 (context',ty,C.LetIn(n,s,bo))
58 CicMkImplicit.identity_relocation_list_for_metavariable context
60 context, t, (C.Meta (newmeta,irl))
62 collect_context context ty
64 let eta_expand metasenv context t arg =
65 let module T = CicTypeChecker in
66 let module S = CicSubstitution in
70 t' when t' = S.lift n arg -> C.Rel (1 + n)
71 | C.Rel m -> if m <= n then C.Rel m else C.Rel (m+1)
72 | C.Var (uri,exp_named_subst) ->
73 let exp_named_subst' = aux_exp_named_subst n exp_named_subst in
74 C.Var (uri,exp_named_subst')
77 | C.Implicit _ as t -> t
78 | C.Cast (te,ty) -> C.Cast (aux n te, aux n ty)
79 | C.Prod (nn,s,t) -> C.Prod (nn, aux n s, aux (n+1) t)
80 | C.Lambda (nn,s,t) -> C.Lambda (nn, aux n s, aux (n+1) t)
81 | C.LetIn (nn,s,t) -> C.LetIn (nn, aux n s, aux (n+1) t)
82 | C.Appl l -> C.Appl (List.map (aux n) l)
83 | C.Const (uri,exp_named_subst) ->
84 let exp_named_subst' = aux_exp_named_subst n exp_named_subst in
85 C.Const (uri,exp_named_subst')
86 | C.MutInd (uri,i,exp_named_subst) ->
87 let exp_named_subst' = aux_exp_named_subst n exp_named_subst in
88 C.MutInd (uri,i,exp_named_subst')
89 | C.MutConstruct (uri,i,j,exp_named_subst) ->
90 let exp_named_subst' = aux_exp_named_subst n exp_named_subst in
91 C.MutConstruct (uri,i,j,exp_named_subst')
92 | C.MutCase (sp,i,outt,t,pl) ->
93 C.MutCase (sp,i,aux n outt, aux n t,
96 let tylen = List.length fl in
99 (fun (name,i,ty,bo) -> (name, i, aux n ty, aux (n+tylen) bo))
102 C.Fix (i, substitutedfl)
104 let tylen = List.length fl in
107 (fun (name,ty,bo) -> (name, aux n ty, aux (n+tylen) bo))
110 C.CoFix (i, substitutedfl)
111 and aux_exp_named_subst n =
112 List.map (function uri,t -> uri,aux n t)
115 T.type_of_aux' metasenv context arg
118 FreshNamesGenerator.mk_fresh_name
119 metasenv context (Cic.Name "Heta") ~typ:argty
121 (C.Appl [C.Lambda (fresh_name,argty,aux 0 t) ; arg])
123 (*CSC: ma serve solamente la prima delle new_uninst e l'unione delle due!!! *)
124 let classify_metas newmeta in_subst_domain subst_in metasenv =
126 (fun (i,canonical_context,ty) (old_uninst,new_uninst) ->
127 if in_subst_domain i then
128 old_uninst,new_uninst
130 let ty' = subst_in canonical_context ty in
131 let canonical_context' =
133 (fun entry canonical_context' ->
136 Some (n,Cic.Decl s) ->
137 Some (n,Cic.Decl (subst_in canonical_context' s))
138 | Some (n,Cic.Def (s,None)) ->
139 Some (n,Cic.Def ((subst_in canonical_context' s),None))
141 | Some (_,Cic.Def (_,Some _)) -> assert false
143 entry'::canonical_context'
144 ) canonical_context []
147 ((i,canonical_context',ty')::old_uninst),new_uninst
149 old_uninst,((i,canonical_context',ty')::new_uninst)
152 (* Auxiliary function for apply: given a type (a backbone), it returns its *)
153 (* head, a META environment in which there is new a META for each hypothesis,*)
154 (* a list of arguments for the new applications and the indexes of the first *)
155 (* and last new METAs introduced. The nth argument in the list of arguments *)
156 (* is just the nth new META. *)
157 let new_metasenv_for_apply newmeta proof context ty =
158 let module C = Cic in
159 let module S = CicSubstitution in
160 let rec aux newmeta =
162 C.Cast (he,_) -> aux newmeta he
163 (* CSC: patch to generate ?1 : ?2 : Type in place of ?1 : Type
164 (* If the expected type is a Type, then also Set is OK ==>
165 * we accept any term of type Type *)
166 (*CSC: BUG HERE: in this way it is possible for the term of
167 * type Type to be different from a Sort!!! *)
168 | C.Prod (name,(C.Sort C.Type as s),t) ->
170 CicMkImplicit.identity_relocation_list_for_metavariable context
172 let newargument = C.Meta (newmeta+1,irl) in
173 let (res,newmetasenv,arguments,lastmeta) =
174 aux (newmeta + 2) (S.subst newargument t)
177 (newmeta,[],s)::(newmeta+1,context,C.Meta (newmeta,[]))::newmetasenv,
178 newargument::arguments,lastmeta
180 | C.Prod (name,s,t) ->
182 CicMkImplicit.identity_relocation_list_for_metavariable context
184 let newargument = C.Meta (newmeta,irl) in
185 let (res,newmetasenv,arguments,lastmeta) =
186 aux (newmeta + 1) (S.subst newargument t)
188 res,(newmeta,context,s)::newmetasenv,newargument::arguments,lastmeta
189 | t -> t,[],[],newmeta
191 (* WARNING: here we are using the invariant that above the most *)
192 (* recente new_meta() there are no used metas. *)
193 let (res,newmetasenv,arguments,lastmeta) = aux newmeta ty in
194 res,newmetasenv,arguments,lastmeta
196 (* Useful only inside apply_tac *)
198 generalize_exp_named_subst_with_fresh_metas context newmeta uri exp_named_subst
200 let module C = Cic in
202 match CicEnvironment.get_obj uri with
203 C.Constant (_,_,_,params)
204 | C.CurrentProof (_,_,_,_,params)
205 | C.Variable (_,_,_,params)
206 | C.InductiveDefinition (_,params,_) -> params
208 let exp_named_subst_diff,new_fresh_meta,newmetasenvfragment,exp_named_subst'=
209 let next_fresh_meta = ref newmeta in
210 let newmetasenvfragment = ref [] in
211 let exp_named_subst_diff = ref [] in
217 match CicEnvironment.get_obj uri with
218 C.Variable (_,_,ty,_) ->
219 CicSubstitution.subst_vars !exp_named_subst_diff ty
220 | _ -> raise (WrongUriToVariable (UriManager.string_of_uri uri))
222 (* CSC: patch to generate ?1 : ?2 : Type in place of ?1 : Type
224 C.Sort C.Type as s ->
225 let fresh_meta = !next_fresh_meta in
226 let fresh_meta' = fresh_meta + 1 in
227 next_fresh_meta := !next_fresh_meta + 2 ;
228 let subst_item = uri,C.Meta (fresh_meta',[]) in
229 newmetasenvfragment :=
230 (fresh_meta,[],C.Sort C.Type) ::
231 (fresh_meta',[],C.Meta (fresh_meta,[])) :: !newmetasenvfragment ;
232 exp_named_subst_diff := !exp_named_subst_diff @ [subst_item] ;
233 subst_item::(aux (tl,[]))
237 CicMkImplicit.identity_relocation_list_for_metavariable context
239 let subst_item = uri,C.Meta (!next_fresh_meta,irl) in
240 newmetasenvfragment :=
241 (!next_fresh_meta,context,ty)::!newmetasenvfragment ;
242 exp_named_subst_diff := !exp_named_subst_diff @ [subst_item] ;
243 incr next_fresh_meta ;
244 subst_item::(aux (tl,[]))(*)*)
245 | uri::tl1,((uri',_) as s)::tl2 ->
246 assert (UriManager.eq uri uri') ;
248 | [],_ -> assert false
250 let exp_named_subst' = aux (params,exp_named_subst) in
251 !exp_named_subst_diff,!next_fresh_meta,
252 List.rev !newmetasenvfragment, exp_named_subst'
254 new_fresh_meta,newmetasenvfragment,exp_named_subst',exp_named_subst_diff
257 let apply_tac ~term (proof, goal) =
258 (* Assumption: The term "term" must be closed in the current context *)
259 let module T = CicTypeChecker in
260 let module R = CicReduction in
261 let module C = Cic in
262 let (_,metasenv,_,_) = proof in
263 let metano,context,ty = CicUtil.lookup_meta goal metasenv in
264 let newmeta = new_meta_of_proof ~proof in
265 let exp_named_subst_diff,newmeta',newmetasenvfragment,term' =
267 C.Var (uri,exp_named_subst) ->
268 let newmeta',newmetasenvfragment,exp_named_subst',exp_named_subst_diff =
269 generalize_exp_named_subst_with_fresh_metas context newmeta uri
272 exp_named_subst_diff,newmeta',newmetasenvfragment,
273 C.Var (uri,exp_named_subst')
274 | C.Const (uri,exp_named_subst) ->
275 let newmeta',newmetasenvfragment,exp_named_subst',exp_named_subst_diff =
276 generalize_exp_named_subst_with_fresh_metas context newmeta uri
279 exp_named_subst_diff,newmeta',newmetasenvfragment,
280 C.Const (uri,exp_named_subst')
281 | C.MutInd (uri,tyno,exp_named_subst) ->
282 let newmeta',newmetasenvfragment,exp_named_subst',exp_named_subst_diff =
283 generalize_exp_named_subst_with_fresh_metas context newmeta uri
286 exp_named_subst_diff,newmeta',newmetasenvfragment,
287 C.MutInd (uri,tyno,exp_named_subst')
288 | C.MutConstruct (uri,tyno,consno,exp_named_subst) ->
289 let newmeta',newmetasenvfragment,exp_named_subst',exp_named_subst_diff =
290 generalize_exp_named_subst_with_fresh_metas context newmeta uri
293 exp_named_subst_diff,newmeta',newmetasenvfragment,
294 C.MutConstruct (uri,tyno,consno,exp_named_subst')
295 | _ -> [],newmeta,[],term
297 let metasenv' = metasenv@newmetasenvfragment in
299 CicSubstitution.subst_vars exp_named_subst_diff
300 (CicTypeChecker.type_of_aux' metasenv' context term)
302 (* newmeta is the lowest index of the new metas introduced *)
303 let (consthead,newmetas,arguments,_) =
304 new_metasenv_for_apply newmeta' proof context termty
306 let newmetasenv = metasenv'@newmetas in
307 let subst,newmetasenv' =
308 CicUnification.fo_unif newmetasenv context consthead ty
310 let in_subst_domain i = List.exists (function (j,_) -> i=j) subst in
311 let apply_subst = CicMetaSubst.apply_subst subst in
312 let old_uninstantiatedmetas,new_uninstantiatedmetas =
313 (* subst_in doesn't need the context. Hence the underscore. *)
314 let subst_in _ = CicMetaSubst.apply_subst subst in
315 classify_metas newmeta in_subst_domain subst_in newmetasenv'
319 (if List.length newmetas = 0 then
322 Cic.Appl (term'::arguments)
325 let newmetasenv'' = new_uninstantiatedmetas@old_uninstantiatedmetas in
326 let (newproof, newmetasenv''') =
327 let subst_in = CicMetaSubst.apply_subst ((metano,bo')::subst) in
328 subst_meta_and_metasenv_in_proof
329 proof metano subst_in newmetasenv''
331 (newproof, List.map (function (i,_,_) -> i) new_uninstantiatedmetas)
333 (* TODO per implementare i tatticali e' necessario che tutte le tattiche
334 sollevino _solamente_ Fail *)
335 let apply_tac ~term status =
337 apply_tac ~term status
338 (* TODO cacciare anche altre eccezioni? *)
339 with CicUnification.UnificationFailure _ as e ->
340 raise (Fail (Printexc.to_string e))
343 ?(mk_fresh_name_callback = FreshNamesGenerator.mk_fresh_name) ()
346 let module C = Cic in
347 let module R = CicReduction in
348 let (_,metasenv,_,_) = proof in
349 let metano,context,ty = CicUtil.lookup_meta goal metasenv in
350 let newmeta = new_meta_of_proof ~proof in
351 let (context',ty',bo') =
352 lambda_abstract metasenv context newmeta ty mk_fresh_name_callback
355 subst_meta_in_proof proof metano bo' [newmeta,context',ty']
357 (newproof, [newmeta])
360 ?(mk_fresh_name_callback = FreshNamesGenerator.mk_fresh_name)
363 let module C = Cic in
364 let curi,metasenv,pbo,pty = proof in
365 let metano,context,ty = CicUtil.lookup_meta goal metasenv in
366 let newmeta1 = new_meta_of_proof ~proof in
367 let newmeta2 = newmeta1 + 1 in
369 mk_fresh_name_callback metasenv context (Cic.Name "Hcut") ~typ:term in
370 let context_for_newmeta1 =
371 (Some (fresh_name,C.Decl term))::context in
373 CicMkImplicit.identity_relocation_list_for_metavariable
377 CicMkImplicit.identity_relocation_list_for_metavariable context
379 let newmeta1ty = CicSubstitution.lift 1 ty in
382 [C.Lambda (fresh_name,term,C.Meta (newmeta1,irl1)) ;
383 C.Meta (newmeta2,irl2)]
386 subst_meta_in_proof proof metano bo'
387 [newmeta2,context,term; newmeta1,context_for_newmeta1,newmeta1ty];
389 (newproof, [newmeta1 ; newmeta2])
392 ?(mk_fresh_name_callback = FreshNamesGenerator.mk_fresh_name)
395 let module C = Cic in
396 let curi,metasenv,pbo,pty = proof in
397 let metano,context,ty = CicUtil.lookup_meta goal metasenv in
398 let _ = CicTypeChecker.type_of_aux' metasenv context term in
399 let newmeta = new_meta_of_proof ~proof in
401 mk_fresh_name_callback metasenv context (Cic.Name "Hletin") ~typ:term in
402 let context_for_newmeta =
403 (Some (fresh_name,C.Def (term,None)))::context in
405 CicMkImplicit.identity_relocation_list_for_metavariable
408 let newmetaty = CicSubstitution.lift 1 ty in
409 let bo' = C.LetIn (fresh_name,term,C.Meta (newmeta,irl)) in
412 proof metano bo'[newmeta,context_for_newmeta,newmetaty]
414 (newproof, [newmeta])
416 (** functional part of the "exact" tactic *)
417 let exact_tac ~term (proof, goal) =
418 (* Assumption: the term bo must be closed in the current context *)
419 let (_,metasenv,_,_) = proof in
420 let metano,context,ty = CicUtil.lookup_meta goal metasenv in
421 let module T = CicTypeChecker in
422 let module R = CicReduction in
423 if R.are_convertible context (T.type_of_aux' metasenv context term) ty then
425 let (newproof, metasenv') =
426 subst_meta_in_proof proof metano term [] in
430 raise (Fail "The type of the provided term is not the one expected.")
433 (* not really "primitive" tactics .... *)
435 let elim_tac ~term (proof, goal) =
436 let module T = CicTypeChecker in
437 let module U = UriManager in
438 let module R = CicReduction in
439 let module C = Cic in
440 let (curi,metasenv,_,_) = proof in
441 let metano,context,ty = CicUtil.lookup_meta goal metasenv in
442 let termty = T.type_of_aux' metasenv context term in
443 let uri,exp_named_subst,typeno,args =
445 C.MutInd (uri,typeno,exp_named_subst) -> (uri,exp_named_subst,typeno,[])
446 | C.Appl ((C.MutInd (uri,typeno,exp_named_subst))::args) ->
447 (uri,exp_named_subst,typeno,args)
448 | _ -> raise NotAnInductiveTypeToEliminate
451 let buri = U.buri_of_uri uri in
453 match CicEnvironment.get_obj uri with
454 C.InductiveDefinition (tys,_,_) ->
455 let (name,_,_,_) = List.nth tys typeno in
460 match T.type_of_aux' metasenv context ty with
461 C.Sort C.Prop -> "_ind"
462 | C.Sort C.Set -> "_rec"
463 | C.Sort C.CProp -> "_rec"
464 | C.Sort C.Type -> "_rect"
467 U.uri_of_string (buri ^ "/" ^ name ^ ext ^ ".con")
469 let eliminator_ref = C.Const (eliminator_uri,exp_named_subst) in
470 let ety = T.type_of_aux' metasenv context eliminator_ref in
471 let newmeta = new_meta_of_proof ~proof in
472 let (econclusion,newmetas,arguments,lastmeta) =
473 new_metasenv_for_apply newmeta proof context ety
475 (* Here we assume that we have only one inductive hypothesis to *)
476 (* eliminate and that it is the last hypothesis of the theorem. *)
477 (* A better approach would be fingering the hypotheses in some *)
480 let (_,canonical_context,_) =
481 CicUtil.lookup_meta (lastmeta - 1) newmetas
484 CicMkImplicit.identity_relocation_list_for_metavariable
487 Cic.Meta (lastmeta - 1, irl)
489 let newmetasenv = newmetas @ metasenv in
490 let subst1,newmetasenv' =
491 CicUnification.fo_unif newmetasenv context term meta_of_corpse
493 let ueconclusion = CicMetaSubst.apply_subst subst1 econclusion in
494 (* The conclusion of our elimination principle is *)
495 (* (?i farg1 ... fargn) *)
496 (* The conclusion of our goal is ty. So, we can *)
497 (* eta-expand ty w.r.t. farg1 .... fargn to get *)
498 (* a new ty equal to (P farg1 ... fargn). Now *)
499 (* ?i can be instantiated with P and we are ready *)
500 (* to refine the term. *)
502 match ueconclusion with
503 C.Appl ((C.Meta (emeta,_))::fargs) -> emeta,fargs
504 | C.Meta (emeta,_) -> emeta,[]
505 | _ -> raise NotTheRightEliminatorShape
507 let ty' = CicMetaSubst.apply_subst subst1 ty in
508 let eta_expanded_ty =
509 (*CSC: newmetasenv' era metasenv ??????????? *)
510 List.fold_left (eta_expand newmetasenv' context) ty' fargs
512 let subst2,newmetasenv'' =
513 (*CSC: passo newmetasenv', ma alcune variabili sono gia' state sostituite
514 da subst1!!!! Dovrei rimuoverle o sono innocue?*)
515 CicUnification.fo_unif
516 newmetasenv' context ueconclusion eta_expanded_ty
518 let in_subst_domain i =
519 let eq_to_i = function (j,_) -> i=j in
520 List.exists eq_to_i subst1 ||
521 List.exists eq_to_i subst2
523 (* When unwinding the META that corresponds to the elimination *)
524 (* predicate (which is emeta), we must also perform one-step *)
525 (* beta-reduction. apply_subst doesn't need the context. Hence *)
526 (* the underscore. *)
527 let apply_subst _ t =
528 let t' = CicMetaSubst.apply_subst subst1 t in
529 CicMetaSubst.apply_subst_reducing
530 (Some (emeta,List.length fargs)) subst2 t'
532 let old_uninstantiatedmetas,new_uninstantiatedmetas =
533 classify_metas newmeta in_subst_domain apply_subst
536 let arguments' = List.map (apply_subst context) arguments in
537 let bo' = Cic.Appl (eliminator_ref::arguments') in
539 new_uninstantiatedmetas@old_uninstantiatedmetas
541 let (newproof, newmetasenv'''') =
542 (* When unwinding the META that corresponds to the *)
543 (* elimination predicate (which is emeta), we must *)
544 (* also perform one-step beta-reduction. *)
545 (* The only difference w.r.t. apply_subst is that *)
546 (* we also substitute metano with bo'. *)
547 (*CSC: Nota: sostituire nuovamente subst1 e' superfluo, *)
550 let t' = CicMetaSubst.apply_subst subst1 t in
551 CicMetaSubst.apply_subst_reducing
552 (Some (emeta,List.length fargs))
553 ((metano,bo')::subst2) t'
555 subst_meta_and_metasenv_in_proof
556 proof metano apply_subst' newmetasenv'''
559 List.map (function (i,_,_) -> i) new_uninstantiatedmetas)
562 (* The simplification is performed only on the conclusion *)
563 let elim_intros_simpl_tac ~term =
564 Tacticals.then_ ~start:(elim_tac ~term)
567 ~start:(intros_tac ())
569 [ReductionTactics.simpl_tac ~also_in_hypotheses:false ~terms:None])
572 exception NotConvertible
574 (*CSC: Bug (or feature?). [with_what] is parsed in the context of the goal, *)
575 (*CSC: while [what] can have a richer context (because of binders) *)
576 (*CSC: So it is _NOT_ possible to use those binders in the [with_what] term. *)
577 (*CSC: Is that evident? Is that right? Or should it be changed? *)
578 let change_tac ~what ~with_what (proof, goal) =
579 let curi,metasenv,pbo,pty = proof in
580 let metano,context,ty = CicUtil.lookup_meta goal metasenv in
581 (* are_convertible works only on well-typed terms *)
582 ignore (CicTypeChecker.type_of_aux' metasenv context with_what) ;
583 if CicReduction.are_convertible context what with_what then
586 ProofEngineReduction.replace
587 ~equality:(==) ~what:[what] ~with_what:[with_what]
589 let ty' = replace ty in
593 Some (name,Cic.Def (t,None)) -> Some (name,Cic.Def ((replace t),None))
594 | Some (name,Cic.Decl t) -> Some (name,Cic.Decl (replace t))
596 | Some (_,Cic.Def (_,Some _)) -> assert false
602 (n,_,_) when n = metano -> (metano,context',ty')
606 (curi,metasenv',pbo,pty), [metano]
609 raise (ProofEngineTypes.Fail "Not convertible")