summaryrefslogtreecommitdiff
path: root/toplevel/himsg.ml
blob: 41783faa552c8a89a50e396781717785758f14ad (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
(************************************************************************)
(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
(*   \VV/  **************************************************************)
(*    //   *      This file is distributed under the terms of the       *)
(*         *       GNU Lesser General Public License Version 2.1        *)
(************************************************************************)

(* $Id: himsg.ml 11309 2008-08-06 10:30:35Z herbelin $ *)

open Pp
open Util
open Flags
open Names
open Nameops
open Term
open Termops
open Inductive
open Indtypes
open Sign
open Environ
open Pretype_errors
open Type_errors
open Typeclasses_errors
open Indrec
open Reduction
open Cases
open Logic
open Printer
open Rawterm
open Evd

let pr_lconstr c = quote (pr_lconstr c)
let pr_lconstr_env e c = quote (pr_lconstr_env e c)
let pr_lconstr_env_at_top e c = quote (pr_lconstr_env_at_top e c)
let pr_ljudge_env e c = let v,t = pr_ljudge_env e c in (quote v,quote t)

let pr_db env i =
  try
    match lookup_rel i env with
        Name id, _, _ -> pr_id id
      | Anonymous, _, _ -> str "<>"
  with Not_found -> str "UNBOUND_REL_" ++ int i

let explain_unbound_rel env n =
  let pe = pr_ne_context_of (str "In environment") env in
  str "Unbound reference: " ++ pe ++
  str "The reference " ++ int n ++ str " is free."

let explain_unbound_var env v =
  let var = pr_id v in
  str "No such section variable or assumption: " ++ var ++ str "."

let explain_not_type env j =
  let pe = pr_ne_context_of (str "In environment") env in
  let pc,pt = pr_ljudge_env env j in
  pe ++ str "The term" ++ brk(1,1) ++ pc ++ spc () ++
  str "has type" ++ spc () ++ pt ++ spc () ++
  str "which should be Set, Prop or Type."

let explain_bad_assumption env j =
  let pe = pr_ne_context_of (str "In environment") env in
  let pc,pt = pr_ljudge_env env j in
  pe ++ str "Cannot declare a variable or hypothesis over the term" ++
  brk(1,1) ++ pc ++ spc () ++ str "of type" ++ spc () ++ pt ++ spc () ++
  str "because this term is not a type."

let explain_reference_variables c =
  let pc = pr_lconstr c in
  str "The constant" ++ spc () ++ pc ++ spc () ++
  str "refers to variables which are not in the context."

let rec pr_disjunction pr = function
  | [a] -> pr  a
  | [a;b] -> pr a ++ str " or" ++ spc () ++ pr b
  | a::l -> pr a ++ str "," ++ spc () ++ pr_disjunction pr l
  | [] -> assert false

let explain_elim_arity env ind sorts c pj okinds =
  let env = make_all_name_different env in
  let pi = pr_inductive env ind in
  let pc = pr_lconstr_env env c in
  let msg = match okinds with
  | Some(kp,ki,explanation) ->
      let pki = pr_sort_family ki in
      let pkp = pr_sort_family kp in
      let explanation =	match explanation with
	| NonInformativeToInformative ->
          "proofs can be eliminated only to build proofs"
	| StrongEliminationOnNonSmallType ->
          "strong elimination on non-small inductive types leads to paradoxes"
	| WrongArity ->
	  "wrong arity" in
      let ppar = pr_disjunction (fun s -> quote (pr_sort_family s)) sorts in
      let ppt = pr_lconstr_env env (snd (decompose_prod_assum pj.uj_type)) in
      hov 0
	(str "the return type has sort" ++ spc () ++ ppt ++ spc () ++
	 str "while it" ++ spc () ++ str "should be " ++ ppar ++ str ".") ++
      fnl () ++
      hov 0
	(str "Elimination of an inductive object of sort " ++
	 pki ++ brk(1,0) ++
         str "is not allowed on a predicate in sort " ++ pkp ++ fnl () ++
         str "because" ++ spc () ++ str explanation ++ str ".")
  | None ->
      str "ill-formed elimination predicate."
  in
  hov 0 (
    str "Incorrect elimination of" ++ spc () ++ pc ++ spc () ++
    str "in the inductive type" ++ spc () ++ quote pi ++ str ":") ++
  fnl () ++ msg

let explain_case_not_inductive env cj =
  let env = make_all_name_different env in
  let pc = pr_lconstr_env env cj.uj_val in
  let pct = pr_lconstr_env env cj.uj_type in
    match kind_of_term cj.uj_type with
      | Evar _ ->
	  str "Cannot infer a type for this expression."
      | _ ->
	  str "The term" ++ brk(1,1) ++ pc ++ spc () ++
	  str "has type" ++ brk(1,1) ++ pct ++ spc () ++
	  str "which is not a (co-)inductive type."

let explain_number_branches env cj expn =
  let env = make_all_name_different env in
  let pc = pr_lconstr_env env cj.uj_val in
  let pct = pr_lconstr_env env cj.uj_type in
  str "Matching on term" ++ brk(1,1) ++ pc ++ spc () ++
  str "of type" ++ brk(1,1) ++ pct ++ spc () ++
  str "expects " ++  int expn ++ str " branches."

let explain_ill_formed_branch env c i actty expty =
  let env = make_all_name_different env in
  let pc = pr_lconstr_env env c in
  let pa = pr_lconstr_env env actty in
  let pe = pr_lconstr_env env expty in
  str "In pattern-matching on term" ++ brk(1,1) ++ pc ++
  spc () ++ str "the " ++ nth (i+1) ++ str " branch has type" ++
  brk(1,1) ++ pa ++ spc () ++
  str "which should be" ++ brk(1,1) ++ pe ++ str "."

let explain_generalization env (name,var) j =
  let pe = pr_ne_context_of (str "In environment") env in
  let pv = pr_ltype_env env var in
  let (pc,pt) = pr_ljudge_env (push_rel_assum (name,var) env) j in
  pe ++ str "Cannot generalize" ++ brk(1,1) ++ pv ++ spc () ++
  str "over" ++ brk(1,1) ++ pc ++ str "," ++ spc () ++
  str "it has type" ++ spc () ++ pt ++
  spc () ++ str "which should be Set, Prop or Type."

let explain_actual_type env j pt =
  let pe = pr_ne_context_of (str "In environment") env in
  let (pc,pct) = pr_ljudge_env env j in
  let pt = pr_lconstr_env env pt in
  pe ++
  str "The term" ++ brk(1,1) ++ pc ++ spc () ++
  str "has type" ++ brk(1,1) ++ pct ++ brk(1,1) ++
  str "while it is expected to have type" ++ brk(1,1) ++ pt ++ str "."

let explain_cant_apply_bad_type env (n,exptyp,actualtyp) rator randl =
  let env = make_all_name_different env in
  let nargs = Array.length randl in
(*  let pe = pr_ne_context_of (str "in environment") env in*)
  let pr,prt = pr_ljudge_env env rator in
  let term_string1 = str (plural nargs "term") in
  let term_string2 =
    if nargs>1 then str "The " ++ nth n ++ str " term" else str "This term" in
  let appl = prvect_with_sep pr_fnl
	       (fun c ->
		  let pc,pct = pr_ljudge_env env c in
		  hov 2 (pc ++ spc () ++ str ": " ++ pct)) randl
  in
  str "Illegal application (Type Error): " ++ (* pe ++ *) fnl () ++
  str "The term" ++ brk(1,1) ++ pr ++ spc () ++
  str "of type" ++ brk(1,1) ++ prt ++ spc () ++
  str "cannot be applied to the " ++ term_string1 ++ fnl () ++
  str " " ++ v 0 appl ++ fnl () ++ term_string2 ++ str " has type" ++
  brk(1,1) ++ pr_lconstr_env env actualtyp ++ spc () ++
  str "which should be coercible to" ++ brk(1,1) ++
  pr_lconstr_env env exptyp ++ str "."

let explain_cant_apply_not_functional env rator randl =
  let env = make_all_name_different env in
  let nargs = Array.length randl in
(*  let pe = pr_ne_context_of (str "in environment") env in*)
  let pr = pr_lconstr_env env rator.uj_val in
  let prt = pr_lconstr_env env rator.uj_type in
  let appl = prvect_with_sep pr_fnl
	       (fun c ->
		  let pc = pr_lconstr_env env c.uj_val in
		  let pct = pr_lconstr_env env c.uj_type in
		  hov 2 (pc ++ spc () ++ str ": " ++ pct)) randl
  in
  str "Illegal application (Non-functional construction): " ++
  (* pe ++ *) fnl () ++
  str "The expression" ++ brk(1,1) ++ pr ++ spc () ++
  str "of type" ++ brk(1,1) ++ prt ++ spc () ++
  str "cannot be applied to the " ++ str (plural nargs "term") ++ fnl () ++
  str " " ++ v 0 appl

let explain_unexpected_type env actual_type expected_type =
  let pract = pr_lconstr_env env actual_type in
  let prexp = pr_lconstr_env env expected_type in
  str "This type is" ++ spc () ++ pract ++ spc () ++
  str "but is expected to be" ++
  spc () ++ prexp ++ str "."

let explain_not_product env c =
  let pr = pr_lconstr_env env c in
  str "The type of this term is a product" ++ spc () ++
  str "while it is expected to be" ++
  (if is_Type c then str " a sort" else (brk(1,1) ++ pr)) ++ str "."

(* TODO: use the names *)
(* (co)fixpoints *)
let explain_ill_formed_rec_body env err names i fixenv vdefj =
  let prt_name i =
    match names.(i) with
        Name id -> str "Recursive definition of " ++ pr_id id
      | Anonymous -> str "The " ++ nth i ++ str " definition" in

  let st = match err with

  (* Fixpoint guard errors *)
  | NotEnoughAbstractionInFixBody ->
      str "Not enough abstractions in the definition"
  | RecursionNotOnInductiveType c ->
      str "Recursive definition on" ++ spc () ++ pr_lconstr_env env c ++ spc () ++
      str "which should be an inductive type"
  | RecursionOnIllegalTerm(j,arg,le,lt) ->
      let called =
        match names.(j) with
            Name id -> pr_id id
          | Anonymous -> str "the " ++ nth i ++ str " definition" in
      let vars =
        match (lt,le) with
            ([],[]) -> assert false
          | ([],[x]) ->
              str "a subterm of " ++ pr_db env x
          | ([],_) ->
              str "a subterm of the following variables: " ++
              prlist_with_sep pr_spc (pr_db env) le
          | ([x],_) -> pr_db env x
          | _ ->
              str "one of the following variables: " ++
              prlist_with_sep pr_spc (pr_db env) lt in
      str "Recursive call to " ++ called ++ spc () ++
      str "has principal argument equal to" ++ spc () ++
      pr_lconstr_env env arg ++ fnl () ++ str "instead of " ++ vars

  | NotEnoughArgumentsForFixCall j ->
      let called =
        match names.(j) with
            Name id -> pr_id id
          | Anonymous -> str "the " ++ nth i ++ str " definition" in
     str "Recursive call to " ++ called ++ str " has not enough arguments"

  (* CoFixpoint guard errors *)
  | CodomainNotInductiveType c ->
      str "The codomain is" ++ spc () ++ pr_lconstr_env env c ++ spc () ++
      str "which should be a coinductive type"
  | NestedRecursiveOccurrences ->
      str "Nested recursive occurrences"
  | UnguardedRecursiveCall c ->
      str "Unguarded recursive call in" ++ spc () ++ pr_lconstr_env env c
  | RecCallInTypeOfAbstraction c ->
      str "Recursive call forbidden in the domain of an abstraction:" ++
      spc () ++ pr_lconstr_env env c
  | RecCallInNonRecArgOfConstructor c ->
      str "Recursive call on a non-recursive argument of constructor" ++
      spc () ++ pr_lconstr_env env c
  | RecCallInTypeOfDef c ->
      str "Recursive call forbidden in the type of a recursive definition" ++
      spc () ++ pr_lconstr_env env c
  | RecCallInCaseFun c ->
      str "Recursive call in a branch of" ++ spc () ++ pr_lconstr_env env c
  | RecCallInCaseArg c ->
      str "Recursive call in the argument of cases in" ++ spc () ++
      pr_lconstr_env env c
  | RecCallInCasePred c ->
      str "Recursive call in the type of cases in" ++  spc () ++
      pr_lconstr_env env c
  | NotGuardedForm c ->
      str "Sub-expression " ++ pr_lconstr_env env c ++
      strbrk " not in guarded form (should be a constructor," ++
      strbrk " an abstraction, a match, a cofix or a recursive call)"
  in
  prt_name i ++ str " is ill-formed." ++ fnl () ++
  pr_ne_context_of (str "In environment") env ++
  st ++ str "."

let explain_ill_typed_rec_body env i names vdefj vargs =
  let env = make_all_name_different env in
  let pvd,pvdt = pr_ljudge_env env (vdefj.(i)) in
  let pv = pr_lconstr_env env vargs.(i) in
  str "The " ++
  (if Array.length vdefj = 1 then mt () else nth (i+1) ++ spc ()) ++
  str "recursive definition" ++ spc () ++ pvd ++ spc () ++
  str "has type" ++ spc () ++ pvdt ++ spc () ++
  str "while it should be" ++ spc () ++ pv ++ str "."

let explain_cant_find_case_type env c =
  let env = make_all_name_different env in
  let pe = pr_lconstr_env env c in
  str "Cannot infer type of pattern-matching on" ++ ws 1 ++ pe ++ str "."

let explain_occur_check env ev rhs =
  let env = make_all_name_different env in
  let id = Evd.string_of_existential ev in
  let pt = pr_lconstr_env env rhs in
  str "Cannot define " ++ str id ++ str " with term" ++ brk(1,1) ++
  pt ++ spc () ++ str "that would depend on itself."

let explain_hole_kind env = function
  | QuestionMark _ -> str "this placeholder"
  | CasesType ->
      str "the type of this pattern-matching problem"
  | BinderType (Name id) ->
      str "the type of " ++ Nameops.pr_id id
  | BinderType Anonymous ->
      str "the type of this anonymous binder"
  | ImplicitArg (c,(n,ido)) ->
      let id = Option.get ido in
      str "the implicit parameter " ++
      pr_id id ++ spc () ++ str "of" ++
      spc () ++ Nametab.pr_global_env Idset.empty c
  | InternalHole ->
      str "an internal placeholder"
  | TomatchTypeParameter (tyi,n) ->
      str "the " ++ nth n ++
      str " argument of the inductive type (" ++ pr_inductive env tyi ++
      str ") of this term"
  | GoalEvar ->
      str "an existential variable"
  | ImpossibleCase ->
      str "the type of an impossible pattern-matching clause"

let explain_not_clean env ev t k =
  let env = make_all_name_different env in
  let id = Evd.string_of_existential ev in
  let var = pr_lconstr_env env t in
  str "Tried to instantiate " ++ explain_hole_kind env k ++
  str " (" ++ str id ++ str ")" ++ spc () ++
  str "with a term using variable " ++ var ++ spc () ++
  str "which is not in its scope."

let explain_unsolvability = function
  | None -> mt()
  | Some (SeveralInstancesFound n) ->
      strbrk " (several distinct possible instances found)"

let pr_ne_context_of header footer env =
  if Environ.rel_context env = empty_rel_context &
    Environ.named_context env = empty_named_context  then footer
  else pr_ne_context_of header env

let explain_typeclass_resolution env evi k =
  match k with
      InternalHole | ImplicitArg _ ->
	(match Typeclasses.class_of_constr evi.evar_concl with
	  | Some c -> 
	      let env = Evd.evar_env evi in
		fnl () ++ str "Could not find an instance for " ++ 
		  pr_lconstr_env env evi.evar_concl ++ 
		  pr_ne_context_of (str " in environment:"++ fnl ()) (str ".") env
	  | None -> mt())
    | _ -> mt()

let explain_unsolvable_implicit env evi k explain =
  str "Cannot infer " ++ explain_hole_kind env k ++ 
  explain_unsolvability explain ++ str "." ++ 
  explain_typeclass_resolution env evi k

let explain_var_not_found env id =
  str "The variable" ++ spc () ++ pr_id id ++
  spc () ++ str "was not found" ++
  spc () ++ str "in the current" ++ spc () ++ str "environment" ++ str "."

let explain_wrong_case_info env ind ci =
  let pi = pr_inductive (Global.env()) ind in
  if ci.ci_ind = ind then
    str "Pattern-matching expression on an object of inductive type" ++
    spc () ++ pi ++ spc () ++ str "has invalid information."
  else
    let pc = pr_inductive (Global.env()) ci.ci_ind in
    str "A term of inductive type" ++ spc () ++ pi ++ spc () ++
    str "was given to a pattern-matching expression on the inductive type" ++
    spc () ++ pc ++ str "."

let explain_cannot_unify env m n =
  let pm = pr_lconstr_env env m in
  let pn = pr_lconstr_env env n in
  str "Impossible to unify" ++ brk(1,1) ++ pm ++ spc () ++
  str "with" ++ brk(1,1) ++ pn ++ str "."

let explain_cannot_unify_local env m n subn =
  let pm = pr_lconstr_env env m in
  let pn = pr_lconstr_env env n in
  let psubn = pr_lconstr_env env subn in
    str "Impossible to unify" ++ brk(1,1) ++ pm ++ spc () ++
      str "with" ++ brk(1,1) ++ pn ++ spc () ++ str "as" ++ brk(1,1) ++
      psubn ++ str " contains local variables."

let explain_refiner_cannot_generalize env ty =
  str "Cannot find a well-typed generalisation of the goal with type: " ++
  pr_lconstr_env env ty ++ str "."

let explain_no_occurrence_found env c id =
  str "Found no subterm matching " ++ pr_lconstr_env env c ++
  str " in " ++ 
    (match id with
      | Some id -> pr_id id
      | None -> str"the current goal") ++ str "."

let explain_cannot_unify_binding_type env m n =
  let pm = pr_lconstr_env env m in
  let pn = pr_lconstr_env env n in
  str "This binding has type" ++ brk(1,1) ++ pm ++ spc () ++
  str "which should be unifiable with" ++ brk(1,1) ++ pn ++ str "."

let explain_cannot_find_well_typed_abstraction env p l =
  str "Abstracting over the " ++
  str (plural (List.length l) "term") ++ spc () ++ 
  hov 0 (pr_enum (pr_lconstr_env env) l) ++ spc () ++
  str "leads to a term" ++ spc () ++ pr_lconstr_env env p ++ spc () ++ 
  str "which is ill-typed."

let explain_type_error env err =
  let env = make_all_name_different env in
  match err with
  | UnboundRel n ->
      explain_unbound_rel env n
  | UnboundVar v ->
      explain_unbound_var env v
  | NotAType j ->
      explain_not_type env j
  | BadAssumption c ->
      explain_bad_assumption env c
  | ReferenceVariables id ->
      explain_reference_variables id
  | ElimArity (ind, aritylst, c, pj, okinds) ->
      explain_elim_arity env ind aritylst c pj okinds
  | CaseNotInductive cj ->
      explain_case_not_inductive env cj
  | NumberBranches (cj, n) ->
      explain_number_branches env cj n
  | IllFormedBranch (c, i, actty, expty) ->
      explain_ill_formed_branch env c i actty expty
  | Generalization (nvar, c) ->
      explain_generalization env nvar c
  | ActualType (j, pt) ->
      explain_actual_type env j pt
  | CantApplyBadType (t, rator, randl) ->
      explain_cant_apply_bad_type env t rator randl
  | CantApplyNonFunctional (rator, randl) ->
      explain_cant_apply_not_functional env rator randl
  | IllFormedRecBody (err, lna, i, fixenv, vdefj) ->
      explain_ill_formed_rec_body env err lna i fixenv vdefj
  | IllTypedRecBody (i, lna, vdefj, vargs) ->
     explain_ill_typed_rec_body env i lna vdefj vargs
  | WrongCaseInfo (ind,ci) ->
      explain_wrong_case_info env ind ci

let explain_pretype_error env err =
  let env = make_all_name_different env in
  match err with
  | CantFindCaseType c -> explain_cant_find_case_type env c
  | OccurCheck (n,c) -> explain_occur_check env n c
  | NotClean (n,c,k) -> explain_not_clean env n c k
  | UnsolvableImplicit (evi,k,exp) -> explain_unsolvable_implicit env evi k exp
  | VarNotFound id -> explain_var_not_found env id
  | UnexpectedType (actual,expect) -> explain_unexpected_type env actual expect
  | NotProduct c -> explain_not_product env c
  | CannotUnify (m,n) -> explain_cannot_unify env m n
  | CannotUnifyLocal (m,n,sn) -> explain_cannot_unify_local env m n sn
  | CannotGeneralize ty -> explain_refiner_cannot_generalize env ty
  | NoOccurrenceFound (c, id) -> explain_no_occurrence_found env c id
  | CannotUnifyBindingType (m,n) -> explain_cannot_unify_binding_type env m n
  | CannotFindWellTypedAbstraction (p,l) ->
      explain_cannot_find_well_typed_abstraction env p l

      
(* Typeclass errors *)

let explain_not_a_class env c =
  pr_constr_env env c ++ str" is not a declared type class."

let explain_unbound_method env cid id =
  str "Unbound method name " ++ Nameops.pr_id (snd id) ++ spc () ++ str"of class" ++ spc () ++ 
    pr_global cid ++ str "."

let pr_constr_exprs exprs = 
  hv 0 (List.fold_right 
	 (fun d pps -> ws 2 ++ Ppconstr.pr_constr_expr d ++ pps)
         exprs (mt ()))

let explain_no_instance env (_,id) l =
  str "No instance found for class " ++ Nameops.pr_id id ++ spc () ++
  str "applied to arguments" ++ spc () ++ 
    prlist_with_sep pr_spc (pr_lconstr_env env) l

let pr_constraints env evm =
  let l = Evd.to_list evm in
  let (ev, evi) = List.hd l in
    if List.for_all (fun (ev', evi') ->
      eq_named_context_val evi.evar_hyps evi'.evar_hyps) l
    then
      let pe = pr_ne_context_of (str "In environment:") (mt ()) 
	(reset_with_named_context evi.evar_hyps env) in
	pe ++ fnl () ++ 
	  prlist_with_sep (fun () -> fnl ()) 
	  (fun (ev, evi) -> str(string_of_existential ev)++ str " == " ++ pr_constr evi.evar_concl) l
    else
      pr_evar_map evm
      
let explain_unsatisfiable_constraints env evd constr =
  let evm = Evd.evars_of evd in
  match constr with
  | None ->
      str"Unable to satisfy the following typeclass constraints:" ++ fnl() ++
	pr_constraints env evm
  | Some (evi, k) -> 
      explain_unsolvable_implicit env evi k None ++ fnl () ++
	if List.length (Evd.to_list evm) > 1 then
	  str"With the following meta variables:" ++ 
	    fnl() ++ Evd.pr_evar_map evm 
	else mt ()
	
let explain_mismatched_contexts env c i j = 
  str"Mismatched contexts while declaring instance: " ++ brk (1,1) ++
    hov 1 (str"Expected:" ++ brk (1, 1) ++ pr_rel_context env j) ++ fnl () ++ brk (1,1) ++ 
    hov 1 (str"Found:" ++ brk (1, 1) ++ pr_constr_exprs i)

let explain_typeclass_error env err = 
  match err with
    | NotAClass c -> explain_not_a_class env c
    | UnboundMethod (cid, id) -> explain_unbound_method env cid id
    | NoInstance (id, l) -> explain_no_instance env id l
    | UnsatisfiableConstraints (evd, c) -> explain_unsatisfiable_constraints env evd c
    | MismatchedContextInstance (c, i, j) -> explain_mismatched_contexts env c i j
	
(* Refiner errors *)

let explain_refiner_bad_type arg ty conclty =
  str "Refiner was given an argument" ++ brk(1,1) ++
  pr_lconstr arg ++ spc () ++
  str "of type" ++ brk(1,1) ++ pr_lconstr ty ++ spc () ++
  str "instead of" ++ brk(1,1) ++ pr_lconstr conclty ++ str "."

let explain_refiner_unresolved_bindings l =
  str "Unable to find an instance for the " ++ 
  str (plural (List.length l) "variable") ++ spc () ++
  prlist_with_sep pr_coma pr_name l ++ str"."

let explain_refiner_cannot_apply t harg =
  str "In refiner, a term of type" ++ brk(1,1) ++
  pr_lconstr t ++ spc () ++ str "could not be applied to" ++ brk(1,1) ++
  pr_lconstr harg ++ str "."

let explain_refiner_not_well_typed c =
  str "The term " ++ pr_lconstr c ++ str " is not well-typed."

let explain_intro_needs_product () =
  str "Introduction tactics needs products."

let explain_does_not_occur_in c hyp =
  str "The term" ++ spc () ++ pr_lconstr c ++ spc () ++
  str "does not occur in" ++ spc () ++ pr_id hyp ++ str "."

let explain_non_linear_proof c =
  str "Cannot refine with term" ++ brk(1,1) ++ pr_lconstr c ++
  spc () ++ str "because a metavariable has several occurrences."

let explain_refiner_error = function
  | BadType (arg,ty,conclty) -> explain_refiner_bad_type arg ty conclty
  | UnresolvedBindings t -> explain_refiner_unresolved_bindings t
  | CannotApply (t,harg) -> explain_refiner_cannot_apply t harg
  | NotWellTyped c -> explain_refiner_not_well_typed c
  | IntroNeedsProduct -> explain_intro_needs_product ()
  | DoesNotOccurIn (c,hyp) -> explain_does_not_occur_in c hyp
  | NonLinearProof c -> explain_non_linear_proof c

(* Inductive errors *)

let error_non_strictly_positive env c v  =
  let pc = pr_lconstr_env env c in
  let pv = pr_lconstr_env env v in
  str "Non strictly positive occurrence of " ++ pv ++ str " in" ++
  brk(1,1) ++ pc ++ str "."

let error_ill_formed_inductive env c v =
  let pc = pr_lconstr_env env c in
  let pv = pr_lconstr_env env v in
  str "Not enough arguments applied to the " ++ pv ++
  str " in" ++ brk(1,1) ++ pc ++ str "."

let error_ill_formed_constructor env id c v nparams nargs =
  let pv = pr_lconstr_env env v in
  let atomic = (nb_prod c = 0) in
  str "The type of constructor" ++ brk(1,1) ++ pr_id id ++ brk(1,1) ++
  str "is not valid;" ++ brk(1,1) ++ 
  strbrk (if atomic then "it must be " else "its conclusion must be ") ++ 
  pv ++ 
  (* warning: because of implicit arguments it is difficult to say which
     parameters must be explicitly given *)
  (if nparams<>0 then
    strbrk " applied to its " ++ str (plural nparams "parameter")
  else
    mt()) ++
  (if nargs<>0 then
     str (if nparams<>0 then " and" else " applied") ++
     strbrk " to some " ++ str (plural nargs "argument")
   else
     mt()) ++ str "."

let error_bad_ind_parameters env c n v1 v2  =
  let pc = pr_lconstr_env_at_top env c in
  let pv1 = pr_lconstr_env env v1 in
  let pv2 = pr_lconstr_env env v2 in
  str "The " ++ nth n ++ str " argument of " ++ pv2 ++ brk(1,1) ++
  str "must be " ++ pv1 ++ str " in" ++ brk(1,1) ++ pc ++ str "."

let error_same_names_types id =
  str "The name" ++ spc () ++ pr_id id ++ spc () ++
  str "is used more than once."

let error_same_names_constructors id =
  str "The constructor name" ++ spc () ++ pr_id id ++ spc () ++
  str "is used more than once."

let error_same_names_overlap idl =
  strbrk "The following names are used both as type names and constructor " ++
  str "names:" ++ spc () ++
  prlist_with_sep pr_coma pr_id idl ++ str "."

let error_not_an_arity id =
  str "The type of" ++ spc () ++ pr_id id ++ spc () ++ str "is not an arity."

let error_bad_entry () =
  str "Bad inductive definition."

let error_not_allowed_case_analysis dep kind i =
  str (if dep then "Dependent" else "Non dependent") ++
  str " case analysis on sort: " ++ pr_sort kind ++ fnl () ++
  str "is not allowed for inductive definition: " ++
  pr_inductive (Global.env()) i ++ str "."

let error_bad_induction dep indid kind =
  str (if dep then "Dependent" else "Non dependent") ++
  str " induction for type " ++ pr_id indid ++
  str " and sort " ++ pr_sort kind ++ spc () ++
  str "is not allowed."

let error_not_mutual_in_scheme ind ind' =
  if ind = ind' then
    str "The inductive type " ++ pr_inductive (Global.env()) ind ++
    str "occurs twice."
  else
    str "The inductive types " ++ pr_inductive (Global.env()) ind ++ spc () ++
    str "and" ++ spc () ++ pr_inductive (Global.env()) ind' ++ spc () ++
    str "are not mutually defined."

(* Inductive constructions errors *)

let explain_inductive_error = function
  | NonPos (env,c,v) -> error_non_strictly_positive env c v
  | NotEnoughArgs (env,c,v) -> error_ill_formed_inductive env c v
  | NotConstructor (env,id,c,v,n,m) ->
      error_ill_formed_constructor env id c v n m
  | NonPar (env,c,n,v1,v2) -> error_bad_ind_parameters env c n v1 v2
  | SameNamesTypes id -> error_same_names_types id
  | SameNamesConstructors id -> error_same_names_constructors id
  | SameNamesOverlap idl -> error_same_names_overlap idl
  | NotAnArity id -> error_not_an_arity id
  | BadEntry -> error_bad_entry ()

(* Recursion schemes errors *)

let explain_recursion_scheme_error = function
  | NotAllowedCaseAnalysis (dep,k,i) ->
      error_not_allowed_case_analysis dep k i
  | BadInduction (dep,indid,kind) -> error_bad_induction dep indid kind
  | NotMutualInScheme (ind,ind')-> error_not_mutual_in_scheme ind ind'

(* Pattern-matching errors *)

let explain_bad_pattern env cstr ty =
  let env = make_all_name_different env in
  let pt = pr_lconstr_env env ty in
  let pc = pr_constructor env cstr in
  str "Found the constructor " ++ pc ++ brk(1,1) ++
  str "while matching a term of type " ++ pt ++ brk(1,1) ++
  str "which is not an inductive type."

let explain_bad_constructor env cstr ind =
  let pi = pr_inductive env ind in
(*  let pc = pr_constructor env cstr in*)
  let pt = pr_inductive env (inductive_of_constructor cstr) in
  str "Found a constructor of inductive type " ++ pt ++ brk(1,1) ++
  str "while a constructor of " ++ pi ++ brk(1,1) ++
  str "is expected."

let decline_string n s =
  if n = 0 then "no "^s^"s"
  else if n = 1 then "1 "^s
  else (string_of_int n^" "^s^"s")

let explain_wrong_numarg_constructor env cstr n =
  str "The constructor " ++ pr_constructor env cstr ++
  str " expects " ++ str (decline_string n "argument") ++ str "."

let explain_wrong_numarg_inductive env ind n =
  str "The inductive type " ++ pr_inductive env ind ++
  str " expects " ++ str (decline_string n "argument") ++ str "."

let explain_wrong_predicate_arity env pred nondep_arity dep_arity=
  let env = make_all_name_different env in
  let pp = pr_lconstr_env env pred in
  str "The elimination predicate " ++ spc () ++ pp ++ fnl () ++
  str "should be of arity" ++ spc () ++
  pr_lconstr_env env nondep_arity ++ spc () ++
  str "(for non dependent case) or" ++
  spc () ++ pr_lconstr_env env dep_arity ++ spc () ++ str "(for dependent case)."

let explain_needs_inversion env x t =
  let env = make_all_name_different env in
  let px = pr_lconstr_env env x in
  let pt = pr_lconstr_env env t in
  str "Sorry, I need inversion to compile pattern matching on term " ++
  px ++ str " of type: " ++ pt ++ str "."

let explain_unused_clause env pats =
(* Without localisation
  let s = if List.length pats > 1 then "s" else "" in
  (str ("Unused clause with pattern"^s) ++ spc () ++
    hov 0 (prlist_with_sep pr_spc pr_cases_pattern pats) ++ str ")")
*)
  str "This clause is redundant."

let explain_non_exhaustive env pats =
  str "Non exhaustive pattern-matching: no clause found for " ++
  str (plural (List.length pats) "pattern") ++
  spc () ++ hov 0 (prlist_with_sep pr_spc pr_cases_pattern pats)

let explain_cannot_infer_predicate env typs =
  let env = make_all_name_different env in
  let pr_branch (cstr,typ) =
    let cstr,_ = decompose_app cstr in
    str "For " ++ pr_lconstr_env env cstr ++ str ": " ++ pr_lconstr_env env typ
  in
  str "Unable to unify the types found in the branches:" ++
  spc () ++ hov 0 (prlist_with_sep pr_fnl pr_branch (Array.to_list typs))

let explain_pattern_matching_error env = function
  | BadPattern (c,t) ->
      explain_bad_pattern env c t
  | BadConstructor (c,ind) ->
      explain_bad_constructor env c ind
  | WrongNumargConstructor (c,n) ->
      explain_wrong_numarg_constructor env c n
  | WrongNumargInductive (c,n) ->
      explain_wrong_numarg_inductive env c n
  | WrongPredicateArity (pred,n,dep) ->
      explain_wrong_predicate_arity env pred n dep
  | NeedsInversion (x,t) ->
      explain_needs_inversion env x t
  | UnusedClause tms ->
      explain_unused_clause env tms
  | NonExhaustive tms ->
      explain_non_exhaustive env tms
  | CannotInferPredicate typs ->
      explain_cannot_infer_predicate env typs

let explain_reduction_tactic_error = function
  | Tacred.InvalidAbstraction (env,c,(env',e)) ->
      str "The abstracted term" ++ spc () ++ pr_lconstr_env_at_top env c ++
      spc () ++ str "is not well typed." ++ fnl () ++
      explain_type_error env' e

let explain_ltac_call_trace (last,trace,loc) =
  let calls = last :: List.rev (List.map snd trace) in
  let pr_call = function
  | Proof_type.LtacNotationCall s -> quote (str s)
  | Proof_type.LtacNameCall cst -> quote (Pptactic.pr_ltac_constant cst)
  | Proof_type.LtacVarCall (id,t) ->
      quote (Nameops.pr_id id) ++ strbrk " (bound to " ++ 
      Pptactic.pr_glob_tactic (Global.env()) t ++ str ")"
  | Proof_type.LtacAtomCall (te,otac) -> quote
      (Pptactic.pr_glob_tactic (Global.env())
	(Tacexpr.TacAtom (dummy_loc,te)))
      ++ (match !otac with
      | Some te' when (Obj.magic te' <> te) ->
	  strbrk " (expanded to " ++ quote
	  (Pptactic.pr_tactic (Global.env())
	    (Tacexpr.TacAtom (dummy_loc,te')))
	++ str ")"
      | _ -> mt ())
  | Proof_type.LtacConstrInterp (c,(vars,unboundvars)) ->
      let filter =
	function (id,None) -> None | (id,Some id') -> Some(id,mkVar id') in
      let unboundvars = list_map_filter filter unboundvars in
      quote (pr_rawconstr_env (Global.env()) c) ++
      (if unboundvars <> [] or vars <> [] then
	strbrk " (with " ++ prlist_with_sep pr_coma (fun (id,c) -> 
	pr_id id ++ str ":=" ++ Printer.pr_lconstr c)
	  (List.rev vars @ unboundvars)
       else mt()) ++ str ")" in
  if calls <> [] then
    let kind_of_last_call = match list_last calls with
    | Proof_type.LtacConstrInterp _ -> ", last term evaluation failed."
    | _ -> ", last call failed." in
    hov 0 (str "In nested Ltac calls to " ++ 
           pr_enum pr_call calls ++ strbrk kind_of_last_call)
  else
    mt ()