2 ||M|| This file is part of HELM, an Hypertextual, Electronic
3 ||A|| Library of Mathematics, developed at the Computer Science
4 ||T|| Department, University of Bologna, Italy.
6 ||T|| HELM is free software; you can redistribute it and/or
7 ||A|| modify it under the terms of the GNU General Public License
8 \ / version 2 or (at your option) any later version.
9 \ / This software is distributed as is, NO WARRANTY.
10 V_______________________________________________________________ *)
15 module Ref = NReference
16 module E = NCicEnvironment
18 exception AssertFailure of string Lazy.t;;
20 module type Strategy = sig
23 type config = int * env_term list * C.term * stack_term list
25 reduce: (delta:int -> config -> config * bool) ->
26 unwind: (config -> C.term) ->
28 val from_stack : delta:int -> stack_term -> config
29 val from_stack_list_for_unwind :
30 unwind: (config -> C.term) -> stack_term list -> C.term list
31 val from_env : delta:int -> env_term -> config
32 val from_env_for_unwind :
33 unwind: (config -> C.term) -> env_term -> C.term
35 reduce: (delta:int -> config -> config * bool) ->
36 unwind: (config -> C.term) ->
37 stack_term -> env_term
39 reduce: (delta:int -> config -> config * bool) ->
40 unwind: (config -> C.term) ->
41 int -> env_term list -> C.term -> env_term
42 val compute_to_stack :
43 reduce: (delta:int -> config -> config * bool) ->
44 unwind: (config -> C.term) ->
49 module CallByValueByNameForUnwind' : Strategy = struct
50 type config = int * env_term list * C.term * stack_term list
52 config Lazy.t * (int -> config) * C.term Lazy.t
54 config Lazy.t (* cbneed ~delta:0 *)
55 * (int -> config) (* cbvalue ~delta *)
56 * C.term Lazy.t (* cbname ~delta:max_int *)
57 let to_env ~reduce ~unwind c =
58 lazy (fst (reduce ~delta:0 c)),
59 (fun delta -> fst (reduce ~delta c)),
61 let from_stack ~delta (c0,c,_) = if delta = 0 then Lazy.force c0 else c delta
62 let from_stack_list_for_unwind ~unwind:_ l =
63 List.map (fun (_,_,c) -> Lazy.force c) l
64 let from_env ~delta (c0,c,_) = if delta = 0 then Lazy.force c0 else c delta
65 let from_env_for_unwind ~unwind:_ (_,_,c) = Lazy.force c
66 let stack_to_env ~reduce:_ ~unwind:_ config = config
67 let compute_to_env ~reduce ~unwind k e t =
68 lazy (fst (reduce ~delta:0 (k,e,t,[]))),
69 (fun delta -> fst (reduce ~delta (k,e,t,[]))),
70 lazy (unwind (k,e,t,[]))
71 let compute_to_stack ~reduce ~unwind config =
72 lazy (fst (reduce ~delta:0 config)),
73 (fun delta -> fst (reduce ~delta config)),
78 module Reduction(RS : Strategy) = struct
79 type env = RS.env_term list
80 type stack = RS.stack_term list
81 type config = int * env * C.term * stack
83 let rec unwind (k,e,t,s) =
87 NCicSubstitution.psubst ~avoid_beta_redexes:true
88 (RS.from_env_for_unwind ~unwind) e t
91 else C.Appl(t::(RS.from_stack_list_for_unwind ~unwind s))
94 let list_nth l n = try List.nth l n with Failure _ -> assert false;;
95 let rec replace i s t =
98 | n,he::tl -> he::(replace (n - 1) tl t)
102 let rec reduce ~delta ?(subst = []) context : config -> config * bool =
103 let rec aux = function
104 | k, e, C.Rel n, s when n <= k ->
105 let k',e',t',s' = RS.from_env ~delta (list_nth e (n-1)) in
107 | k, _, C.Rel n, s as config (* when n > k *) ->
108 let x= try Some (List.nth context (n - 1 - k)) with Failure _ -> None in
110 | Some(_,C.Def(x,_)) -> aux (0,[],NCicSubstitution.lift (n - k) x,s)
112 | (k, e, C.Meta (n,l), s) as config ->
114 let _,_, term,_ = NCicUtils.lookup_subst n subst in
115 aux (k, e, NCicSubstitution.subst_meta l term,s)
116 with NCicUtils.Subst_not_found _ -> config, true)
117 | (_, _, C.Implicit _, _) -> assert false
118 | (_, _, C.Sort _, _)
119 | (_, _, C.Prod _, _)
120 | (_, _, C.Lambda _, []) as config -> config, true
121 | (k, e, C.Lambda (_,_,t), p::s) ->
122 aux (k+1, (RS.stack_to_env ~reduce:(reduce ~subst context) ~unwind p)::e, t,s)
123 | (k, e, C.LetIn (_,_,m,t), s) ->
124 let m' = RS.compute_to_env ~reduce:(reduce ~subst context) ~unwind k e m in
125 aux (k+1, m'::e, t, s)
126 | (_, _, C.Appl ([]|[_]), _) -> assert false
127 | (k, e, C.Appl (he::tl), s) ->
129 List.map (fun t->RS.compute_to_stack
130 ~reduce:(reduce ~subst context) ~unwind (k,e,t,[])) tl
132 aux (k, e, he, tl' @ s)
134 (Ref.Ref (_,Ref.Def height) as refer), s) as config ->
135 if delta >= height then
138 let _,_,body,_,_,_ = NCicEnvironment.get_checked_def refer in
140 | (_, _, C.Const (Ref.Ref (_,
141 (Ref.Decl|Ref.Ind _|Ref.Con _|Ref.CoFix _))), _) as config ->
143 | (_, _, (C.Const (Ref.Ref
144 (_,Ref.Fix (fixno,recindex,height)) as refer)),s) as config ->
145 (let arg = try Some (List.nth s recindex) with Failure _ -> None in
149 let fixes,(_,_,pragma),_ =
150 NCicEnvironment.get_checked_fixes_or_cofixes refer in
151 if delta >= height then
154 (match RS.from_stack ~delta:max_int arg with
155 | _,_,C.Const(Ref.Ref(_,Ref.Con _)),_::_ ->
156 let _,_,_,_,body = List.nth fixes fixno in
161 match RS.from_stack ~delta:0 arg with
162 | (_,_,C.Const (Ref.Ref (_,Ref.Con _)), _) as c ->
165 (RS.compute_to_stack ~reduce:(reduce ~subst context)
167 let _,_,_,_,body = List.nth fixes fixno in
168 aux (0, [], body, new_s)
170 | (k, e, C.Match (_,_,term,pl),s) as config ->
171 let decofix = function
172 | (_,_,C.Const(Ref.Ref(_,Ref.CoFix c)as refer),s)->
174 NCicEnvironment.get_checked_fixes_or_cofixes refer in
175 let _,_,_,_,body = List.nth cofixes c in
176 let c,_ = reduce ~delta:0 ~subst context (0,[],body,s) in
180 let match_head = k,e,term,[] in
181 let reduced,_ = reduce ~delta:0 ~subst context match_head in
182 (match decofix reduced with
183 | (_, _, C.Const (Ref.Ref (_,Ref.Con (_,j,_))),[]) ->
184 aux (k, e, List.nth pl (j-1), s)
185 | (_, _, C.Const (Ref.Ref (_,Ref.Con (_,j,lno))), s')->
186 let _,params = HExtlib.split_nth lno s' in
187 aux (k, e, List.nth pl (j-1), params@s)
193 let whd ?(delta=0) ~subst context t =
194 unwind (fst (reduce ~delta ~subst context (0, [], t, [])))
201 module RS = CallByValueByNameForUnwind';;
202 module R = Reduction(RS);;
206 let (===) x y = Pervasives.compare x y = 0 ;;
208 let get_relevance = ref (fun ~metasenv:_ ~subst:_ _ _ -> assert false);;
210 let set_get_relevance f = get_relevance := f;;
212 let alpha_eq ~test_lambda_source aux test_eq_only metasenv subst context t1 t2 =
217 | C.Sort s1, C.Sort s2 ->
218 NCicEnvironment.are_sorts_convertible ~test_eq_only s1 s2
220 | (C.Prod (name1,s1,t1), C.Prod(_,s2,t2)) ->
221 aux true context s1 s2 &&
222 aux test_eq_only ((name1, C.Decl s1)::context) t1 t2
223 | (C.Lambda (name1,s1,t1), C.Lambda(_,_,t2)) ->
224 if test_lambda_source then
225 aux test_eq_only context t1 t2
227 (* thanks to inversion of well typedness, the source
228 * of these lambdas must be already convertible *)
229 aux test_eq_only ((name1, C.Decl s1)::context) t1 t2
230 | (C.LetIn (name1,ty1,s1,t1), C.LetIn(_,ty2,s2,t2)) ->
231 aux test_eq_only context ty1 ty2 &&
232 aux test_eq_only context s1 s2 &&
233 aux test_eq_only ((name1, C.Def (s1,ty1))::context) t1 t2
235 | (C.Meta (n1,(s1, C.Irl _)), C.Meta (n2,(s2, C.Irl _)))
236 when n1 = n2 && s1 = s2 -> true
237 | (C.Meta (n1,(s1, l1)), C.Meta (n2,(s2, l2))) when n1 = n2 &&
238 let l1 = NCicUtils.expand_local_context l1 in
239 let l2 = NCicUtils.expand_local_context l2 in
241 (fun t1 t2 -> aux test_eq_only context
242 (NCicSubstitution.lift s1 t1)
243 (NCicSubstitution.lift s2 t2))
245 with Invalid_argument "List.for_all2" ->
246 prerr_endline ("Meta " ^ string_of_int n1 ^
247 " occurrs with local contexts of different lenght\n"^
248 NCicPp.ppterm ~metasenv ~subst ~context t1 ^ " === " ^
249 NCicPp.ppterm ~metasenv ~subst ~context t2);
250 assert false) -> true
252 | C.Meta (n1,l1), _ ->
254 let _,_,term,_ = NCicUtils.lookup_subst n1 subst in
255 let term = NCicSubstitution.subst_meta l1 term in
256 aux test_eq_only context term t2
257 with NCicUtils.Subst_not_found _ -> false)
258 | _, C.Meta (n2,l2) ->
260 let _,_,term,_ = NCicUtils.lookup_subst n2 subst in
261 let term = NCicSubstitution.subst_meta l2 term in
262 aux test_eq_only context t1 term
263 with NCicUtils.Subst_not_found _ -> false)
265 | (C.Appl ((C.Const r1) as hd1::tl1), C.Appl (C.Const r2::tl2))
266 when (Ref.eq r1 r2 &&
267 List.length (E.get_relevance r1) >= List.length tl1) ->
268 let relevance = E.get_relevance r1 in
269 let relevance = match r1 with
270 | Ref.Ref (_,Ref.Con (_,_,lno)) ->
271 let _,relevance = HExtlib.split_nth lno relevance in
272 HExtlib.mk_list false lno @ relevance
276 HExtlib.list_forall_default3_var
277 (fun t1 t2 b -> not b || aux true context t1 t2 )
278 tl1 tl2 true relevance
279 with Invalid_argument _ -> false
280 | HExtlib.FailureAt fail ->
282 !get_relevance ~metasenv ~subst context hd1 tl1 in
283 let _,relevance = HExtlib.split_nth fail relevance in
284 let b,relevance = (match relevance with
288 let _,tl1 = HExtlib.split_nth (fail+1) tl1 in
289 let _,tl2 = HExtlib.split_nth (fail+1) tl2 in
291 HExtlib.list_forall_default3
292 (fun t1 t2 b -> not b || aux true context t1 t2)
293 tl1 tl2 true relevance
294 with Invalid_argument _ -> false
297 | (C.Appl (hd1::tl1), C.Appl (hd2::tl2)) ->
298 aux test_eq_only context hd1 hd2 &&
299 let relevance = !get_relevance ~metasenv ~subst context hd1 tl1 in
301 HExtlib.list_forall_default3
302 (fun t1 t2 b -> not b || aux true context t1 t2)
303 tl1 tl2 true relevance
304 with Invalid_argument _ -> false)
306 | (C.Match (Ref.Ref (_,Ref.Ind (_,tyno,_)) as ref1,outtype1,term1,pl1),
307 C.Match (ref2,outtype2,term2,pl2)) ->
308 let _,_,itl,_,_ = E.get_checked_indtys ref1 in
309 let _,_,ty,_ = List.nth itl tyno in
310 let rec remove_prods ~subst context ty =
311 let ty = whd ~subst context ty in
314 | C.Prod (name,so,ta) -> remove_prods ~subst ((name,(C.Decl so))::context) ta
318 match remove_prods ~subst [] ty with
319 | C.Sort C.Prop -> true
323 aux test_eq_only context outtype1 outtype2 &&
324 (is_prop || aux test_eq_only context term1 term2) &&
325 (try List.for_all2 (aux test_eq_only context) pl1 pl2
326 with Invalid_argument _ -> false)
327 | (C.Implicit _, _) | (_, C.Implicit _) -> assert false
331 (* t1, t2 must be well-typed *)
332 let are_convertible ~metasenv ~subst =
333 let rec aux test_eq_only context t1 t2 =
334 let alpha_eq test_eq_only =
335 alpha_eq ~test_lambda_source:false aux test_eq_only metasenv subst context
337 if alpha_eq test_eq_only t1 t2 then
340 let height_of = function
341 | C.Const (Ref.Ref (_,Ref.Def h))
342 | C.Const (Ref.Ref (_,Ref.Fix (_,_,h)))
343 | C.Appl(C.Const(Ref.Ref(_,Ref.Def h))::_)
344 | C.Appl(C.Const(Ref.Ref(_,Ref.Fix (_,_,h)))::_) -> h
347 let put_in_whd m1 m2 =
348 R.reduce ~delta:max_int ~subst context m1,
349 R.reduce ~delta:max_int ~subst context m2
352 ((_,_,t1,_ as m1), norm1 as x1) ((_,_,t2,_ as m2), norm2 as x2)
354 assert(not (norm1 && norm2));
356 x1, R.reduce ~delta:(height_of t2 -1) ~subst context m2
358 R.reduce ~delta:(height_of t1 -1) ~subst context m1, x2
360 let h1 = height_of t1 in
361 let h2 = height_of t2 in
362 let delta = if h1 = h2 then max 0 (h1 -1) else min h1 h2 in
363 R.reduce ~delta ~subst context m1,
364 R.reduce ~delta ~subst context m2
366 let rec convert_machines test_eq_only
367 ((k1,e1,t1,s1),norm1 as m1),((k2,e2,t2,s2), norm2 as m2)
369 (alpha_eq test_eq_only
370 (R.unwind (k1,e1,t1,[])) (R.unwind (k2,e2,t2,[])) &&
373 C.Const r -> NCicEnvironment.get_relevance r
376 HExtlib.list_forall_default3
379 let t1 = RS.from_stack ~delta:max_int t1 in
380 let t2 = RS.from_stack ~delta:max_int t2 in
381 convert_machines true (put_in_whd t1 t2)) s1 s2 true relevance
382 with Invalid_argument _ -> false) ||
383 (not (norm1 && norm2) && convert_machines test_eq_only (small_delta_step m1 m2))
385 convert_machines test_eq_only (put_in_whd (0,[],t1,[]) (0,[],t2,[]))
390 let alpha_eq metasenv subst =
391 let rec aux test_lambda_source context t1 t2 =
392 alpha_eq ~test_lambda_source aux true metasenv subst context t1 t2
397 let rec head_beta_reduce ~delta ~upto ~subst t l =
398 match upto, t, l with
399 | 0, C.Appl l1, _ -> C.Appl (l1 @ l)
401 | 0, t, _ -> C.Appl (t::l)
402 | _, C.Meta (n,ctx), _ ->
404 let _,_, term,_ = NCicUtils.lookup_subst n subst in
405 head_beta_reduce ~delta ~upto ~subst
406 (NCicSubstitution.subst_meta ctx term) l
407 with NCicUtils.Subst_not_found _ -> if l = [] then t else C.Appl (t::l))
408 | _, C.Appl (hd::tl), _ -> head_beta_reduce ~delta ~upto ~subst hd (tl @ l)
409 | _, C.Lambda(_,_,bo), arg::tl ->
410 let bo = NCicSubstitution.subst arg bo in
411 head_beta_reduce ~delta ~upto:(upto - 1) ~subst bo tl
412 | _, C.Const (Ref.Ref (_, Ref.Def height) as re), _
413 when delta <= height ->
414 let _, _, bo, _, _, _ = NCicEnvironment.get_checked_def re in
415 head_beta_reduce ~upto ~delta ~subst bo l
417 | _, t, _ -> C.Appl (t::l)
420 let head_beta_reduce ?(delta=max_int) ?(upto= -1) ?(subst=[]) t =
421 head_beta_reduce ~delta ~upto ~subst t []
424 type stack_item = RS.stack_term
425 type environment_item = RS.env_term
427 type machine = int * environment_item list * NCic.term * stack_item list
429 let reduce_machine = R.reduce
430 let from_stack = RS.from_stack
431 let unwind = R.unwind
434 NCicUtils.set_head_beta_reduce (fun ~upto t -> head_beta_reduce ~upto t);
435 NCicPp.set_head_beta_reduce (fun ~upto t -> head_beta_reduce ~upto t);
438 (* if n < 0, then splits all prods from an arity, returning a sort *)
439 let rec split_prods ~subst context n te =
440 match (n, R.whd ~subst context te) with
441 | (0, _) -> context,te
442 | (n, C.Sort _) when n <= 0 -> context,te
443 | (n, C.Prod (name,so,ta)) ->
444 split_prods ~subst ((name,(C.Decl so))::context) (n - 1) ta
445 | (_, _) -> raise (AssertFailure (lazy "split_prods"))
448 (* vim:set foldmethod=marker: *)