summaryrefslogtreecommitdiff
path: root/src/elab_util.sml
blob: 0cdb9cc136fc21e286dd17d40c5747c952daf3dc (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
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
(* Copyright (c) 2008-2010, Adam Chlipala
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - The names of contributors may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *)

structure ElabUtil :> ELAB_UTIL = struct

open Elab

fun classifyDatatype xncs =
    case xncs of
        [(_, _, NONE), (_, _, SOME _)] => Option
      | [(_, _, SOME _), (_, _, NONE)] => Option
      | _ =>
        if List.all (fn (_, _, NONE) => true | _ => false) xncs then
            Enum
        else
            Default

structure S = Search

structure Kind = struct

fun mapfoldB {kind, bind} =
    let
        fun mfk ctx k acc =
            S.bindP (mfk' ctx k acc, kind ctx)

        and mfk' ctx (kAll as (k, loc)) =
            case k of
                KType => S.return2 kAll

              | KArrow (k1, k2) =>
                S.bind2 (mfk ctx k1,
                      fn k1' =>
                         S.map2 (mfk ctx k2,
                              fn k2' =>
                                 (KArrow (k1', k2'), loc)))

              | KName => S.return2 kAll

              | KRecord k =>
                S.map2 (mfk ctx k,
                        fn k' =>
                           (KRecord k', loc))

              | KUnit => S.return2 kAll

              | KTuple ks =>
                S.map2 (ListUtil.mapfold (mfk ctx) ks,
                        fn ks' =>
                           (KTuple ks', loc))

              | KError => S.return2 kAll

              | KUnif (_, _, ref (KKnown k)) => mfk' ctx k
              | KUnif _ => S.return2 kAll

              | KTupleUnif (_, _, ref (KKnown k)) => mfk' ctx k
              | KTupleUnif (loc, nks, r) =>
                S.map2 (ListUtil.mapfold (fn (n, k) =>
                                             S.map2 (mfk ctx k,
                                                  fn k' =>
                                                     (n, k'))) nks,
                     fn nks' =>
                        (KTupleUnif (loc, nks', r), loc))


              | KRel _ => S.return2 kAll
              | KFun (x, k) =>
                S.map2 (mfk (bind (ctx, x)) k,
                        fn k' =>
                           (KFun (x, k'), loc))
    in
        mfk
    end

fun mapfold fk =
    mapfoldB {kind = fn () => fk,
              bind = fn ((), _) => ()} ()

fun mapB {kind, bind} ctx k =
    case mapfoldB {kind = fn ctx => fn k => fn () => S.Continue (kind ctx k, ()),
                   bind = bind} ctx k () of
        S.Continue (k, ()) => k
      | S.Return _ => raise Fail "ElabUtil.Kind.mapB: Impossible"

fun exists f k =
    case mapfold (fn k => fn () =>
                             if f k then
                                 S.Return ()
                             else
                                 S.Continue (k, ())) k () of
        S.Return _ => true
      | S.Continue _ => false

fun foldB {kind, bind} ctx st k =
    case mapfoldB {kind = fn ctx => fn k => fn st => S.Continue (k, kind (ctx, k, st)),
                   bind = bind} ctx k st of
        S.Continue (_, st) => st
      | S.Return _ => raise Fail "ElabUtil.Kind.foldB: Impossible"

end

val mliftConInCon = ref (fn n : int => fn c : con => (raise Fail "You didn't set ElabUtil.mliftConInCon!") : con)

structure Con = struct

datatype binder =
         RelK of string
       | RelC of string * Elab.kind
       | NamedC of string * int * Elab.kind * Elab.con option

fun mapfoldB {kind = fk, con = fc, bind} =
    let
        val mfk = Kind.mapfoldB {kind = fk, bind = fn (ctx, s) => bind (ctx, RelK s)}

        fun mfc ctx c acc =
            S.bindP (mfc' ctx c acc, fc ctx)

        and mfc' ctx (cAll as (c, loc)) =
            case c of
                TFun (c1, c2) =>
                S.bind2 (mfc ctx c1,
                      fn c1' =>
                         S.map2 (mfc ctx c2,
                              fn c2' =>
                                 (TFun (c1', c2'), loc)))
              | TCFun (e, x, k, c) =>
                S.bind2 (mfk ctx k,
                      fn k' =>
                         S.map2 (mfc (bind (ctx, RelC (x, k))) c,
                              fn c' =>
                                 (TCFun (e, x, k', c'), loc)))
              | TDisjoint (c1, c2, c3) =>
                S.bind2 (mfc ctx c1,
                      fn c1' =>
                         S.bind2 (mfc ctx c2,
                              fn c2' =>
                                 S.map2 (mfc ctx c3,
                                         fn c3' =>
                                            (TDisjoint (c1', c2', c3'), loc))))
              | TRecord c =>
                S.map2 (mfc ctx c,
                        fn c' =>
                           (TRecord c', loc))

              | CRel _ => S.return2 cAll
              | CNamed _ => S.return2 cAll
              | CModProj _ => S.return2 cAll
              | CApp (c1, c2) =>
                S.bind2 (mfc ctx c1,
                      fn c1' =>
                         S.map2 (mfc ctx c2,
                              fn c2' =>
                                 (CApp (c1', c2'), loc)))
              | CAbs (x, k, c) =>
                S.bind2 (mfk ctx k,
                      fn k' =>
                         S.map2 (mfc (bind (ctx, RelC (x, k))) c,
                              fn c' =>
                                 (CAbs (x, k', c'), loc)))

              | CName _ => S.return2 cAll

              | CRecord (k, xcs) =>
                S.bind2 (mfk ctx k,
                      fn k' =>
                         S.map2 (ListUtil.mapfold (fn (x, c) =>
                                                      S.bind2 (mfc ctx x,
                                                            fn x' =>
                                                               S.map2 (mfc ctx c,
                                                                    fn c' =>
                                                                       (x', c'))))
                                 xcs,
                              fn xcs' =>
                                 (CRecord (k', xcs'), loc)))
              | CConcat (c1, c2) =>
                S.bind2 (mfc ctx c1,
                      fn c1' =>
                         S.map2 (mfc ctx c2,
                              fn c2' =>
                                 (CConcat (c1', c2'), loc)))
              | CMap (k1, k2) =>
                S.bind2 (mfk ctx k1,
                         fn k1' =>
                            S.map2 (mfk ctx k2,
                                    fn k2' =>
                                       (CMap (k1', k2'), loc)))

              | CUnit => S.return2 cAll

              | CTuple cs =>
                S.map2 (ListUtil.mapfold (mfc ctx) cs,
                        fn cs' =>
                           (CTuple cs', loc))

              | CProj (c, n) =>
                S.map2 (mfc ctx c,
                        fn c' =>
                           (CProj (c', n), loc))

              | CError => S.return2 cAll
              | CUnif (nl, _, _, _, ref (Known c)) => mfc' ctx (!mliftConInCon nl c)
              | CUnif _ => S.return2 cAll
                        
              | CKAbs (x, c) =>
                S.map2 (mfc (bind (ctx, RelK x)) c,
                        fn c' =>
                           (CKAbs (x, c'), loc))
              | CKApp (c, k) =>
                S.bind2 (mfc ctx c,
                      fn c' =>
                         S.map2 (mfk ctx k,
                                 fn k' =>
                                    (CKApp (c', k'), loc)))
              | TKFun (x, c) =>
                S.map2 (mfc (bind (ctx, RelK x)) c,
                        fn c' =>
                           (TKFun (x, c'), loc))
    in
        mfc
    end

fun mapfold {kind = fk, con = fc} =
    mapfoldB {kind = fn () => fk,
              con = fn () => fc,
              bind = fn ((), _) => ()} ()

fun mapB {kind, con, bind} ctx c =
    case mapfoldB {kind = fn ctx => fn k => fn () => S.Continue (kind ctx k, ()),
                   con = fn ctx => fn c => fn () => S.Continue (con ctx c, ()),
                   bind = bind} ctx c () of
        S.Continue (c, ()) => c
      | S.Return _ => raise Fail "ElabUtil.Con.mapB: Impossible"

fun map {kind, con} s =
    case mapfold {kind = fn k => fn () => S.Continue (kind k, ()),
                  con = fn c => fn () => S.Continue (con c, ())} s () of
        S.Return () => raise Fail "ElabUtil.Con.map: Impossible"
      | S.Continue (s, ()) => s

fun appB {kind, con, bind} ctx c =
    case mapfoldB {kind = fn ctx => fn k => fn () => (kind ctx k; S.Continue (k, ())),
                   con = fn ctx => fn c => fn () => (con ctx c; S.Continue (c, ())),
                   bind = bind} ctx c () of
        S.Continue _ => ()
      | S.Return _ => raise Fail "ElabUtil.Con.appB: Impossible"

fun app {kind, con} s =
    case mapfold {kind = fn k => fn () => (kind k; S.Continue (k, ())),
                  con = fn c => fn () => (con c; S.Continue (c, ()))} s () of
        S.Return () => raise Fail "ElabUtil.Con.app: Impossible"
      | S.Continue _ => ()

fun existsB {kind, con, bind} ctx c =
    case mapfoldB {kind = fn ctx => fn k => fn () =>
                                               if kind (ctx, k) then
                                                   S.Return ()
                                               else
                                                   S.Continue (k, ()),
                   con = fn ctx => fn c => fn () =>
                                              if con (ctx, c) then
                                                  S.Return ()
                                              else
                                                  S.Continue (c, ()),
                   bind = bind} ctx c () of
        S.Return _ => true
      | S.Continue _ => false

fun exists {kind, con} c =
    case mapfold {kind = fn k => fn () =>
                                    if kind k then
                                        S.Return ()
                                    else
                                        S.Continue (k, ()),
                  con = fn c => fn () =>
                                    if con c then
                                        S.Return ()
                                    else
                                        S.Continue (c, ())} c () of
        S.Return _ => true
      | S.Continue _ => false

fun foldB {kind, con, bind} ctx st c =
    case mapfoldB {kind = fn ctx => fn k => fn st => S.Continue (k, kind (ctx, k, st)),
                   con = fn ctx => fn c => fn st => S.Continue (c, con (ctx, c, st)),
                   bind = bind} ctx c st of
        S.Continue (_, st) => st
      | S.Return _ => raise Fail "ElabUtil.Con.foldB: Impossible"

fun fold {kind, con} st c =
    case mapfoldB {kind = fn () => fn k => fn st => S.Continue (k, kind (k, st)),
                   con = fn () => fn c => fn st => S.Continue (c, con (c, st)),
                   bind = fn ((), _) => ()} () c st of
        S.Continue (_, st) => st
      | S.Return _ => raise Fail "ElabUtil.Con.fold: Impossible"

end

structure Exp = struct

datatype binder =
         RelK of string
       | RelC of string * Elab.kind
       | NamedC of string * int * Elab.kind * Elab.con option
       | RelE of string * Elab.con
       | NamedE of string * Elab.con

fun mapfoldB {kind = fk, con = fc, exp = fe, bind} =
    let
        val mfk = Kind.mapfoldB {kind = fk, bind = fn (ctx, x) => bind (ctx, RelK x)}

        fun bind' (ctx, b) =
            let
                val b' = case b of
                             Con.RelK x => RelK x
                           | Con.RelC x => RelC x
                           | Con.NamedC x => NamedC x
            in
                bind (ctx, b')
            end
        val mfc = Con.mapfoldB {kind = fk, con = fc, bind = bind'}

        fun doVars ((p, _), ctx) =
            case p of
                PVar xt => bind (ctx, RelE xt)
              | PPrim _ => ctx
              | PCon (_, _, _, NONE) => ctx
              | PCon (_, _, _, SOME p) => doVars (p, ctx)
              | PRecord xpcs =>
                foldl (fn ((_, p, _), ctx) => doVars (p, ctx))
                      ctx xpcs

        fun mfe ctx e acc =
            S.bindP (mfe' ctx e acc, fe ctx)

        and mfe' ctx (eAll as (e, loc)) =
            case e of
                EPrim _ => S.return2 eAll
              | ERel _ => S.return2 eAll
              | ENamed _ => S.return2 eAll
              | EModProj _ => S.return2 eAll
              | EApp (e1, e2) =>
                S.bind2 (mfe ctx e1,
                      fn e1' =>
                         S.map2 (mfe ctx e2,
                              fn e2' =>
                                 (EApp (e1', e2'), loc)))
              | EAbs (x, dom, ran, e) =>
                S.bind2 (mfc ctx dom,
                      fn dom' =>
                         S.bind2 (mfc ctx ran,
                                  fn ran' =>
                                     S.map2 (mfe (bind (ctx, RelE (x, dom'))) e,
                                          fn e' =>
                                             (EAbs (x, dom', ran', e'), loc))))
                         
              | ECApp (e, c) =>
                S.bind2 (mfe ctx e,
                      fn e' =>
                         S.map2 (mfc ctx c,
                              fn c' =>
                                 (ECApp (e', c'), loc)))
              | ECAbs (expl, x, k, e) =>
                S.bind2 (mfk ctx k,
                      fn k' =>
                         S.map2 (mfe (bind (ctx, RelC (x, k))) e,
                              fn e' =>
                                 (ECAbs (expl, x, k', e'), loc)))

              | ERecord xes =>
                S.map2 (ListUtil.mapfold (fn (x, e, t) =>
                                             S.bind2 (mfc ctx x,
                                                   fn x' =>
                                                      S.bind2 (mfe ctx e,
                                                           fn e' =>
                                                              S.map2 (mfc ctx t,
                                                                   fn t' =>
                                                                      (x', e', t')))))
                                         xes,
                     fn xes' =>
                        (ERecord xes', loc))
              | EField (e, c, {field, rest}) =>
                S.bind2 (mfe ctx e,
                      fn e' =>
                         S.bind2 (mfc ctx c,
                              fn c' =>
                                 S.bind2 (mfc ctx field,
                                          fn field' =>
                                             S.map2 (mfc ctx rest,
                                                  fn rest' =>
                                                     (EField (e', c', {field = field', rest = rest'}), loc)))))
              | EConcat (e1, c1, e2, c2) =>
                S.bind2 (mfe ctx e1,
                      fn e1' =>
                         S.bind2 (mfc ctx c1,
                              fn c1' =>
                                 S.bind2 (mfe ctx e2,
                                       fn e2' =>
                                          S.map2 (mfc ctx c2,
                                               fn c2' =>
                                                  (EConcat (e1', c1', e2', c2'),
                                                   loc)))))
              | ECut (e, c, {field, rest}) =>
                S.bind2 (mfe ctx e,
                      fn e' =>
                         S.bind2 (mfc ctx c,
                              fn c' =>
                                 S.bind2 (mfc ctx field,
                                          fn field' =>
                                             S.map2 (mfc ctx rest,
                                                  fn rest' =>
                                                     (ECut (e', c', {field = field', rest = rest'}), loc)))))

              | ECutMulti (e, c, {rest}) =>
                S.bind2 (mfe ctx e,
                      fn e' =>
                         S.bind2 (mfc ctx c,
                              fn c' =>
                                 S.map2 (mfc ctx rest,
                                      fn rest' =>
                                         (ECutMulti (e', c', {rest = rest'}), loc))))

              | ECase (e, pes, {disc, result}) =>
                S.bind2 (mfe ctx e,
                         fn e' =>
                            S.bind2 (ListUtil.mapfold (fn (p, e) =>
                                                          let
                                                              fun pb ((p, _), ctx) =
                                                                  case p of
                                                                      PVar (x, t) => bind (ctx, RelE (x, t))
                                                                    | PPrim _ => ctx
                                                                    | PCon (_, _, _, NONE) => ctx
                                                                    | PCon (_, _, _, SOME p) => pb (p, ctx)
                                                                    | PRecord xps => foldl (fn ((_, p, _), ctx) =>
                                                                                               pb (p, ctx)) ctx xps
                                                          in
                                                              S.bind2 (mfp ctx p,
                                                                       fn p' =>
                                                                          S.map2 (mfe (pb (p', ctx)) e,
                                                                               fn e' => (p', e')))
                                                          end) pes,
                                    fn pes' =>
                                       S.bind2 (mfc ctx disc,
                                             fn disc' =>
                                                S.map2 (mfc ctx result,
                                                     fn result' =>
                                                        (ECase (e', pes', {disc = disc', result = result'}), loc)))))

              | EError => S.return2 eAll
              | EUnif (ref (SOME e)) => mfe ctx e
              | EUnif _ => S.return2 eAll

              | ELet (des, e, t) =>
                let
                    val (des, ctx') = foldl (fn (ed, (des, ctx)) =>
                                                let
                                                    val ctx' =
                                                        case #1 ed of
                                                            EDVal (p, _, _) => doVars (p, ctx)
                                                          | EDValRec vis =>
                                                            foldl (fn ((x, t, _), ctx) => bind (ctx, RelE (x, t)))
                                                                  ctx vis
                                                in
                                                    (S.bind2 (des,
                                                           fn des' =>
                                                              S.map2 (mfed ctx ed,
                                                                   fn ed' => ed' :: des')),
                                                     ctx')
                                                end)
                                            (S.return2 [], ctx) des
                in
                    S.bind2 (des,
                         fn des' =>
                            S.bind2 (mfe ctx' e,
                                    fn e' =>
                                       S.map2 (mfc ctx t,
                                               fn t' =>
                                                  (ELet (rev des', e', t'), loc))))
                end

              | EKAbs (x, e) =>
                S.map2 (mfe (bind (ctx, RelK x)) e,
                        fn e' =>
                           (EKAbs (x, e'), loc))
              | EKApp (e, k) =>
                S.bind2 (mfe ctx e,
                        fn e' =>
                           S.map2 (mfk ctx k,
                                   fn k' =>
                                      (EKApp (e', k'), loc)))

        and mfp ctx (pAll as (p, loc)) =
            case p of
                PVar (x, t) =>
                S.map2 (mfc ctx t,
                        fn t' =>
                           (PVar (x, t'), loc))
              | PPrim _ => S.return2 pAll
              | PCon (dk, pc, args, po) =>
                S.bind2 (ListUtil.mapfold (mfc ctx) args,
                      fn args' =>
                         S.map2 ((case po of
                                      NONE => S.return2 NONE
                                    | SOME p => S.map2 (mfp ctx p, SOME)),
                              fn po' =>
                                 (PCon (dk, pc, args', po'), loc)))
              | PRecord xps =>
                S.map2 (ListUtil.mapfold (fn (x, p, c) =>
                                              S.bind2 (mfp ctx p,
                                                       fn p' =>
                                                          S.map2 (mfc ctx c,
                                                                  fn c' =>
                                                                     (x, p', c')))) xps,
                         fn xps' =>
                            (PRecord xps', loc))

        and mfed ctx (dAll as (d, loc)) =
            case d of
                EDVal (p, t, e) =>
                S.bind2 (mfc ctx t,
                         fn t' =>
                            S.map2 (mfe ctx e,
                                 fn e' =>
                                    (EDVal (p, t', e'), loc)))
              | EDValRec vis =>
                let
                    val ctx = foldl (fn ((x, t, _), ctx) => bind (ctx, RelE (x, t))) ctx vis
                in
                    S.map2 (ListUtil.mapfold (mfvi ctx) vis,
                         fn vis' =>
                            (EDValRec vis', loc))
                end

        and mfvi ctx (x, c, e) =
            S.bind2 (mfc ctx c,
                  fn c' =>
                     S.map2 (mfe ctx e,
                          fn e' =>
                             (x, c', e')))
    in
        mfe
    end

fun mapfold {kind = fk, con = fc, exp = fe} =
    mapfoldB {kind = fn () => fk,
              con = fn () => fc,
              exp = fn () => fe,
              bind = fn ((), _) => ()} ()

fun existsB {kind, con, exp, bind} ctx e =
    case mapfoldB {kind = fn ctx => fn k => fn () =>
                                               if kind (ctx, k) then
                                                   S.Return ()
                                               else
                                                   S.Continue (k, ()),
                   con = fn ctx => fn c => fn () =>
                                              if con (ctx, c) then
                                                  S.Return ()
                                              else
                                                  S.Continue (c, ()),
                   exp = fn ctx => fn e => fn () =>
                                              if exp (ctx, e) then
                                                  S.Return ()
                                              else
                                                  S.Continue (e, ()),
                   bind = bind} ctx e () of
        S.Return _ => true
      | S.Continue _ => false

fun exists {kind, con, exp} k =
    case mapfold {kind = fn k => fn () =>
                                    if kind k then
                                        S.Return ()
                                    else
                                        S.Continue (k, ()),
                  con = fn c => fn () =>
                                    if con c then
                                        S.Return ()
                                    else
                                        S.Continue (c, ()),
                  exp = fn e => fn () =>
                                    if exp e then
                                        S.Return ()
                                    else
                                        S.Continue (e, ())} k () of
        S.Return _ => true
      | S.Continue _ => false

fun mapB {kind, con, exp, bind} ctx e =
    case mapfoldB {kind = fn ctx => fn k => fn () => S.Continue (kind ctx k, ()),
                   con = fn ctx => fn c => fn () => S.Continue (con ctx c, ()),
                   exp = fn ctx => fn e => fn () => S.Continue (exp ctx e, ()),
                   bind = bind} ctx e () of
        S.Continue (e, ()) => e
      | S.Return _ => raise Fail "ElabUtil.Exp.mapB: Impossible"

fun foldB {kind, con, exp, bind} ctx st e =
    case mapfoldB {kind = fn ctx => fn k => fn st => S.Continue (k, kind (ctx, k, st)),
                   con = fn ctx => fn c => fn st => S.Continue (c, con (ctx, c, st)),
                   exp = fn ctx => fn e => fn st => S.Continue (e, exp (ctx, e, st)),
                   bind = bind} ctx e st of
        S.Continue (_, st) => st
      | S.Return _ => raise Fail "ElabUtil.Exp.foldB: Impossible"

end

structure Sgn = struct

datatype binder =
         RelK of string
       | RelC of string * Elab.kind
       | NamedC of string * int * Elab.kind * Elab.con option
       | Str of string * int * Elab.sgn
       | Sgn of string * int * Elab.sgn

fun mapfoldB {kind, con, sgn_item, sgn, bind} =
    let
        fun bind' (ctx, b) =
            let
                val b' = case b of
                             Con.RelK x => RelK x
                           | Con.RelC x => RelC x
                           | Con.NamedC x => NamedC x
            in
                bind (ctx, b')
            end
        val con = Con.mapfoldB {kind = kind, con = con, bind = bind'}

        val kind = Kind.mapfoldB {kind = kind, bind = fn (ctx, x) => bind (ctx, RelK x)}

        fun sgi ctx si acc =
            S.bindP (sgi' ctx si acc, sgn_item ctx)

        and sgi' ctx (siAll as (si, loc)) =
            case si of
                SgiConAbs (x, n, k) =>
                S.map2 (kind ctx k,
                     fn k' =>
                        (SgiConAbs (x, n, k'), loc))
              | SgiCon (x, n, k, c) =>
                S.bind2 (kind ctx k,
                     fn k' =>
                        S.map2 (con ctx c,
                             fn c' =>
                                (SgiCon (x, n, k', c'), loc)))
              | SgiDatatype dts =>
                S.map2 (ListUtil.mapfold (fn (x, n, xs, xncs) =>
                                             S.map2 (ListUtil.mapfold (fn (x, n, c) =>
                                                                          case c of
                                                                              NONE => S.return2 (x, n, c)
                                                                            | SOME c =>
                                                                              S.map2 (con ctx c,
                                                                                   fn c' => (x, n, SOME c'))) xncs,
                                                  fn xncs' => (x, n, xs, xncs'))) dts,
                        fn dts' =>
                           (SgiDatatype dts', loc))
              | SgiDatatypeImp (x, n, m1, ms, s, xs, xncs) =>
                S.map2 (ListUtil.mapfold (fn (x, n, c) =>
                                             case c of
                                                 NONE => S.return2 (x, n, c)
                                               | SOME c =>
                                                 S.map2 (con ctx c,
                                                      fn c' => (x, n, SOME c'))) xncs,
                        fn xncs' =>
                           (SgiDatatypeImp (x, n, m1, ms, s, xs, xncs'), loc))
              | SgiVal (x, n, c) =>
                S.map2 (con ctx c,
                     fn c' =>
                        (SgiVal (x, n, c'), loc))
              | SgiStr (im, x, n, s) =>
                S.map2 (sg ctx s,
                     fn s' =>
                        (SgiStr (im, x, n, s'), loc))
              | SgiSgn (x, n, s) =>
                S.map2 (sg ctx s,
                     fn s' =>
                        (SgiSgn (x, n, s'), loc))
              | SgiConstraint (c1, c2) =>
                S.bind2 (con ctx c1,
                         fn c1' =>
                            S.map2 (con ctx c2,
                                    fn c2' =>
                                       (SgiConstraint (c1', c2'), loc)))
              | SgiClassAbs (x, n, k) =>
                S.map2 (kind ctx k,
                        fn k' =>
                           (SgiClassAbs (x, n, k'), loc))
              | SgiClass (x, n, k, c) =>
                S.bind2 (kind ctx k,
                      fn k' => 
                         S.map2 (con ctx c,
                              fn c' =>
                                 (SgiClass (x, n, k', c'), loc)))

        and sg ctx s acc =
            S.bindP (sg' ctx s acc, sgn ctx)

        and sg' ctx (sAll as (s, loc)) =
            case s of
                SgnConst sgis =>
                S.map2 (ListUtil.mapfoldB (fn (ctx, si)  =>
                                              (case #1 si of
                                                   SgiConAbs (x, n, k) =>
                                                   bind (ctx, NamedC (x, n, k, NONE))
                                                 | SgiCon (x, n, k, c) =>
                                                   bind (ctx, NamedC (x, n, k, SOME c))
                                                 | SgiDatatype dts =>
                                                   foldl (fn ((x, n, ks, _), ctx) =>
                                                             let
                                                                 val k' = (KType, loc)
                                                                 val k = foldl (fn (_, k) => (KArrow (k', k), loc))
                                                                               k' ks
                                                             in
                                                                 bind (ctx, NamedC (x, n, k, NONE))
                                                             end) ctx dts
                                                 | SgiDatatypeImp (x, n, m1, ms, s, _, _) =>
                                                   bind (ctx, NamedC (x, n, (KType, loc),
                                                                      SOME (CModProj (m1, ms, s), loc)))
                                                 | SgiVal _ => ctx
                                                 | SgiStr (_, x, n, sgn) =>
                                                   bind (ctx, Str (x, n, sgn))
                                                 | SgiSgn (x, n, sgn) =>
                                                   bind (ctx, Sgn (x, n, sgn))
                                                 | SgiConstraint _ => ctx
                                                 | SgiClassAbs (x, n, k) =>
                                                   bind (ctx, NamedC (x, n, (KArrow (k, (KType, loc)), loc), NONE))
                                                 | SgiClass (x, n, k, c) =>
                                                   bind (ctx, NamedC (x, n, (KArrow (k, (KType, loc)), loc), SOME c)),
                                               sgi ctx si)) ctx sgis,
                     fn sgis' =>
                        (SgnConst sgis', loc))
                
              | SgnVar _ => S.return2 sAll
              | SgnFun (m, n, s1, s2) =>
                S.bind2 (sg ctx s1,
                         fn s1' =>
                            S.map2 (sg (bind (ctx, Str (m, n, s1'))) s2,
                                    fn s2' =>
                                       (SgnFun (m, n, s1', s2'), loc)))
              | SgnProj _ => S.return2 sAll
              | SgnWhere (sgn, ms, x, c) =>
                S.bind2 (sg ctx sgn,
                      fn sgn' =>
                         S.map2 (con ctx c,
                              fn c' =>
                                 (SgnWhere (sgn', ms, x, c'), loc)))
              | SgnError => S.return2 sAll
    in
        sg
    end

fun mapfold {kind, con, sgn_item, sgn} =
    mapfoldB {kind = fn () => kind,
              con = fn () => con,
              sgn_item = fn () => sgn_item,
              sgn = fn () => sgn,
              bind = fn ((), _) => ()} ()

fun mapB {kind, con, sgn_item, sgn, bind} ctx s =
    case mapfoldB {kind = fn ctx => fn k => fn () => S.Continue (kind ctx k, ()),
                   con = fn ctx => fn c => fn () => S.Continue (con ctx c, ()),
                   sgn_item = fn ctx => fn sgi => fn () => S.Continue (sgn_item ctx sgi, ()),
                   sgn = fn ctx => fn s => fn () => S.Continue (sgn ctx s, ()),
                   bind = bind} ctx s () of
        S.Continue (s, ()) => s
      | S.Return _ => raise Fail "ElabUtil.Sgn.mapB: Impossible"

fun map {kind, con, sgn_item, sgn} s =
    case mapfold {kind = fn k => fn () => S.Continue (kind k, ()),
                  con = fn c => fn () => S.Continue (con c, ()),
                  sgn_item = fn si => fn () => S.Continue (sgn_item si, ()),
                  sgn = fn s => fn () => S.Continue (sgn s, ())} s () of
        S.Return () => raise Fail "Elab_util.Sgn.map"
      | S.Continue (s, ()) => s

end

structure Decl = struct

datatype binder =
         RelK of string
       | RelC of string * Elab.kind
       | NamedC of string * int * Elab.kind * Elab.con option
       | RelE of string * Elab.con
       | NamedE of string * Elab.con
       | Str of string * int * Elab.sgn
       | Sgn of string * int * Elab.sgn

fun mapfoldB {kind = fk, con = fc, exp = fe, sgn_item = fsgi, sgn = fsg, str = fst, decl = fd, bind} =
    let
        val mfk = Kind.mapfoldB {kind = fk, bind = fn (ctx, x) => bind (ctx, RelK x)}

        fun bind' (ctx, b) =
            let
                val b' = case b of
                             Con.RelK x => RelK x
                           | Con.RelC x => RelC x
                           | Con.NamedC x => NamedC x
            in
                bind (ctx, b')
            end
        val mfc = Con.mapfoldB {kind = fk, con = fc, bind = bind'}

        fun bind' (ctx, b) =
            let
                val b' = case b of
                             Exp.RelK x => RelK x
                           | Exp.RelC x => RelC x
                           | Exp.NamedC x => NamedC x
                           | Exp.RelE x => RelE x
                           | Exp.NamedE x => NamedE x
            in
                bind (ctx, b')
            end
        val mfe = Exp.mapfoldB {kind = fk, con = fc, exp = fe, bind = bind'}

        fun bind' (ctx, b) =
            let
                val b' = case b of
                             Sgn.RelK x => RelK x
                           | Sgn.RelC x => RelC x
                           | Sgn.NamedC x => NamedC x
                           | Sgn.Sgn x => Sgn x
                           | Sgn.Str x => Str x
            in
                bind (ctx, b')
            end
        val mfsg = Sgn.mapfoldB {kind = fk, con = fc, sgn_item = fsgi, sgn = fsg, bind = bind'}

        fun mfst ctx str acc =
            S.bindP (mfst' ctx str acc, fst ctx)

        and mfst' ctx (strAll as (str, loc)) =
            case str of
                StrConst ds => 
                S.map2 (ListUtil.mapfoldB (fn (ctx, d)  =>
                                              (case #1 d of
                                                   DCon (x, n, k, c) =>
                                                   bind (ctx, NamedC (x, n, k, SOME c))
                                                 | DDatatype dts =>
                                                   let
                                                       fun doOne ((x, n, xs, xncs), ctx) =
                                                           let
                                                               val ctx = bind (ctx, NamedC (x, n, (KType, loc), NONE))
                                                           in
                                                               foldl (fn ((x, _, co), ctx) =>
                                                                         let
                                                                             val t =
                                                                                 case co of
                                                                                     NONE => CNamed n
                                                                                   | SOME t => TFun (t, (CNamed n, loc))
                                                                                               
                                                                             val k = (KType, loc)
                                                                             val t = (t, loc)
                                                                             val t = foldr (fn (x, t) =>
                                                                                               (TCFun (Explicit,
                                                                                                       x,
                                                                                                       k,
                                                                                                       t), loc))
                                                                                           t xs
                                                                         in
                                                                             bind (ctx, NamedE (x, t))
                                                                         end)
                                                                     ctx xncs
                                                           end
                                                   in
                                                       foldl doOne ctx dts
                                                   end
                                                 | DDatatypeImp (x, n, m, ms, x', _, _) =>
                                                   bind (ctx, NamedC (x, n, (KType, loc),
                                                                      SOME (CModProj (m, ms, x'), loc)))
                                                 | DVal (x, _, c, _) =>
                                                   bind (ctx, NamedE (x, c))
                                                 | DValRec vis =>
                                                   foldl (fn ((x, _, c, _), ctx) => bind (ctx, NamedE (x, c))) ctx vis
                                                 | DSgn (x, n, sgn) =>
                                                   bind (ctx, Sgn (x, n, sgn))
                                                 | DStr (x, n, sgn, _) =>
                                                   bind (ctx, Str (x, n, sgn))
                                                 | DFfiStr (x, n, sgn) =>
                                                   bind (ctx, Str (x, n, sgn))
                                                 | DConstraint _ => ctx
                                                 | DExport _ => ctx
                                                 | DTable (tn, x, n, c, _, pc, _, cc) =>
                                                   let
                                                       val ct = (CModProj (n, [], "sql_table"), loc)
                                                       val ct = (CApp (ct, c), loc)
                                                       val ct = (CApp (ct, (CConcat (pc, cc), loc)), loc)
                                                   in
                                                       bind (ctx, NamedE (x, ct))
                                                   end
                                                 | DSequence (tn, x, n) =>
                                                   bind (ctx, NamedE (x, (CModProj (n, [], "sql_sequence"), loc)))
                                                 | DView (tn, x, n, _, c) =>
                                                   let
                                                       val ct = (CModProj (n, [], "sql_view"), loc)
                                                       val ct = (CApp (ct, c), loc)
                                                   in
                                                       bind (ctx, NamedE (x, ct))
                                                   end
                                                 | DDatabase _ => ctx
                                                 | DCookie (tn, x, n, c) =>
                                                   bind (ctx, NamedE (x, (CApp ((CModProj (n, [], "cookie"), loc),
                                                                                c), loc)))
                                                 | DStyle (tn, x, n) =>
                                                   bind (ctx, NamedE (x, (CModProj (n, [], "css_class"), loc)))
                                                 | DTask _ => ctx
                                                 | DPolicy _ => ctx
                                                 | DOnError _ => ctx
                                                 | DFfi (x, _, _, t) => bind (ctx, NamedE (x, t)),
                                               mfd ctx d)) ctx ds,
                     fn ds' => (StrConst ds', loc))
              | StrVar _ => S.return2 strAll
              | StrProj (str, x) =>
                S.map2 (mfst ctx str,
                        fn str' =>
                           (StrProj (str', x), loc))
              | StrFun (x, n, sgn1, sgn2, str) =>
                S.bind2 (mfsg ctx sgn1,
                         fn sgn1' =>
                            S.bind2 (mfsg ctx sgn2,
                                     fn sgn2' =>
                                        S.map2 (mfst ctx str,
                                                fn str' =>
                                                   (StrFun (x, n, sgn1', sgn2', str'), loc))))
              | StrApp (str1, str2) =>
                S.bind2 (mfst ctx str1,
                         fn str1' =>
                            S.map2 (mfst ctx str2,
                                    fn str2' =>
                                       (StrApp (str1', str2'), loc)))
              | StrError => S.return2 strAll

        and mfd ctx d acc =
            S.bindP (mfd' ctx d acc, fd ctx)

        and mfd' ctx (dAll as (d, loc)) =
            case d of
                DCon (x, n, k, c) =>
                S.bind2 (mfk ctx k,
                         fn k' =>
                            S.map2 (mfc ctx c,
                                    fn c' =>
                                       (DCon (x, n, k', c'), loc)))
              | DDatatype dts =>
                S.map2 (ListUtil.mapfold (fn (x, n, xs, xncs) =>
                                             S.map2 (ListUtil.mapfold (fn (x, n, c) =>
                                                                          case c of
                                                                              NONE => S.return2 (x, n, c)
                                                                            | SOME c =>
                                                                              S.map2 (mfc ctx c,
                                                                                   fn c' => (x, n, SOME c'))) xncs,
                                                     fn xncs' =>
                                                        (x, n, xs, xncs'))) dts,
                     fn dts' =>
                        (DDatatype dts', loc))
              | DDatatypeImp (x, n, m1, ms, s, xs, xncs) =>
                S.map2 (ListUtil.mapfold (fn (x, n, c) =>
                                             case c of
                                                 NONE => S.return2 (x, n, c)
                                               | SOME c =>
                                                 S.map2 (mfc ctx c,
                                                      fn c' => (x, n, SOME c'))) xncs,
                        fn xncs' =>
                           (DDatatypeImp (x, n, m1, ms, s, xs, xncs'), loc))
              | DVal vi =>
                S.map2 (mfvi ctx vi,
                     fn vi' =>
                        (DVal vi', loc))
              | DValRec vis =>
                S.map2 (ListUtil.mapfold (mfvi ctx) vis,
                     fn vis' =>
                        (DValRec vis', loc))
              | DSgn (x, n, sgn) =>
                S.map2 (mfsg ctx sgn,
                        fn sgn' =>
                           (DSgn (x, n, sgn'), loc))
              | DStr (x, n, sgn, str) =>
                S.bind2 (mfsg ctx sgn,
                         fn sgn' =>
                            S.map2 (mfst ctx str,
                                    fn str' =>
                                       (DStr (x, n, sgn', str'), loc)))
              | DFfiStr (x, n, sgn) =>
                S.map2 (mfsg ctx sgn,
                        fn sgn' =>
                           (DFfiStr (x, n, sgn'), loc))
              | DConstraint (c1, c2) =>
                S.bind2 (mfc ctx c1,
                         fn c1' =>
                            S.map2 (mfc ctx c2,
                                    fn c2' =>
                                       (DConstraint (c1', c2'), loc)))
              | DExport (en, sgn, str) =>
                S.bind2 (mfsg ctx sgn,
                         fn sgn' =>
                            S.map2 (mfst ctx str,
                                    fn str' =>
                                       (DExport (en, sgn', str'), loc)))

              | DTable (tn, x, n, c, pe, pc, ce, cc) =>
                S.bind2 (mfc ctx c,
                        fn c' =>
                           S.bind2 (mfe ctx pe,
                                   fn pe' =>
                                      S.bind2 (mfc ctx pc,
                                            fn pc' =>
                                               S.bind2 (mfe ctx ce,
                                                     fn ce' =>
                                                        S.map2 (mfc ctx cc,
                                                              fn cc' =>
                                                                 (DTable (tn, x, n, c', pe', pc', ce', cc'), loc))))))
              | DSequence _ => S.return2 dAll
              | DView (tn, x, n, e, c) =>
                S.bind2 (mfe ctx e,
                        fn e' =>
                           S.map2 (mfc ctx c,
                                   fn c' =>
                                      (DView (tn, x, n, e', c'), loc)))

              | DDatabase _ => S.return2 dAll

              | DCookie (tn, x, n, c) =>
                S.map2 (mfc ctx c,
                        fn c' =>
                           (DCookie (tn, x, n, c'), loc))
              | DStyle _ => S.return2 dAll
              | DTask (e1, e2) =>
                S.bind2 (mfe ctx e1,
                        fn e1' =>
                           S.map2 (mfe ctx e2,
                                fn e2' =>
                                   (DTask (e1', e2'), loc)))
              | DPolicy e1 =>
                S.map2 (mfe ctx e1,
                     fn e1' =>
                        (DPolicy e1', loc))
              | DOnError _ => S.return2 dAll
              | DFfi (x, n, modes, t) =>
                S.map2 (mfc ctx t,
                        fn t' =>
                           (DFfi (x, n, modes, t'), loc))

        and mfvi ctx (x, n, c, e) =
            S.bind2 (mfc ctx c,
                  fn c' =>
                     S.map2 (mfe ctx e,
                          fn e' =>
                             (x, n, c', e')))
    in
        mfd
    end

fun mapfold {kind, con, exp, sgn_item, sgn, str, decl} =
    mapfoldB {kind = fn () => kind,
              con = fn () => con,
              exp = fn () => exp,
              sgn_item = fn () => sgn_item,
              sgn = fn () => sgn,
              str = fn () => str,
              decl = fn () => decl,
              bind = fn ((), _) => ()} ()

fun exists {kind, con, exp, sgn_item, sgn, str, decl} k =
    case mapfold {kind = fn k => fn () =>
                                    if kind k then
                                        S.Return ()
                                    else
                                        S.Continue (k, ()),
                  con = fn c => fn () =>
                                    if con c then
                                        S.Return ()
                                    else
                                        S.Continue (c, ()),
                  exp = fn e => fn () =>
                                    if exp e then
                                        S.Return ()
                                    else
                                        S.Continue (e, ()),
                  sgn_item = fn sgi => fn () =>
                                        if sgn_item sgi then
                                            S.Return ()
                                        else
                                            S.Continue (sgi, ()),
                  sgn = fn x => fn () =>
                                   if sgn x then
                                       S.Return ()
                                   else
                                       S.Continue (x, ()),
                  str = fn x => fn () =>
                                   if str x then
                                       S.Return ()
                                   else
                                       S.Continue (x, ()),
                  decl = fn x => fn () =>
                                    if decl x then
                                        S.Return ()
                                    else
                                        S.Continue (x, ())} k () of
        S.Return _ => true
      | S.Continue _ => false

fun search {kind, con, exp, sgn_item, sgn, str, decl} k =
    case mapfold {kind = fn x => fn () =>
                                    case kind x of
                                        NONE => S.Continue (x, ())
                                      | SOME v => S.Return v,

                  con = fn x => fn () =>
                                   case con x of
                                       NONE => S.Continue (x, ())
                                     | SOME v => S.Return v,

                  exp = fn x => fn () =>
                                   case exp x of
                                       NONE => S.Continue (x, ())
                                     | SOME v => S.Return v,

                  sgn_item = fn x => fn () =>
                                        case sgn_item x of
                                            NONE => S.Continue (x, ())
                                          | SOME v => S.Return v,

                  sgn = fn x => fn () =>
                                   case sgn x of
                                       NONE => S.Continue (x, ())
                                     | SOME v => S.Return v,

                  str = fn x => fn () =>
                                   case str x of
                                       NONE => S.Continue (x, ())
                                     | SOME v => S.Return v,

                  decl = fn x => fn () =>
                                    case decl x of
                                        NONE => S.Continue (x, ())
                                      | SOME v => S.Return v

                 } k () of
        S.Return x => SOME x
      | S.Continue _ => NONE

fun foldMapB {kind, con, exp, sgn_item, sgn, str, decl, bind} ctx st d =
    case mapfoldB {kind = fn ctx => fn x => fn st => S.Continue (kind (ctx, x, st)),
                   con = fn ctx => fn x => fn st => S.Continue (con (ctx, x, st)),
                   exp = fn ctx => fn x => fn st => S.Continue (exp (ctx, x, st)),
                   sgn_item = fn ctx => fn x => fn st => S.Continue (sgn_item (ctx, x, st)),
                   sgn = fn ctx => fn x => fn st => S.Continue (sgn (ctx, x, st)),
                   str = fn ctx => fn x => fn st => S.Continue (str (ctx, x, st)),
                   decl = fn ctx => fn x => fn st => S.Continue (decl (ctx, x, st)),
                   bind = bind} ctx d st of
        S.Continue x => x
      | S.Return _ => raise Fail "ElabUtil.Decl.foldMapB: Impossible"

fun map {kind, con, exp, sgn_item, sgn, str, decl} s =
    case mapfold {kind = fn k => fn () => S.Continue (kind k, ()),
                  con = fn c => fn () => S.Continue (con c, ()),
                  exp = fn e => fn () => S.Continue (exp e, ()),
                  sgn_item = fn si => fn () => S.Continue (sgn_item si, ()),
                  sgn = fn s => fn () => S.Continue (sgn s, ()),
                  str = fn si => fn () => S.Continue (str si, ()),
                  decl = fn s => fn () => S.Continue (decl s, ())} s () of
        S.Return () => raise Fail "Elab_util.Decl.map"
      | S.Continue (s, ()) => s

fun mapB {kind, con, exp, sgn_item, sgn, str, decl, bind} ctx s =
    case mapfoldB {kind = fn ctx => fn k => fn () => S.Continue (kind ctx k, ()),
                   con = fn ctx => fn c => fn () => S.Continue (con ctx c, ()),
                   exp = fn ctx => fn c => fn () => S.Continue (exp ctx c, ()),
                   sgn_item = fn ctx => fn sgi => fn () => S.Continue (sgn_item ctx sgi, ()),
                   sgn = fn ctx => fn s => fn () => S.Continue (sgn ctx s, ()),
                   str = fn ctx => fn sgi => fn () => S.Continue (str ctx sgi, ()),
                   decl = fn ctx => fn s => fn () => S.Continue (decl ctx s, ()),
                   bind = bind} ctx s () of
        S.Continue (s, ()) => s
      | S.Return _ => raise Fail "ElabUtil.Decl.mapB: Impossible"

fun fold {kind, con, exp, sgn_item, sgn, str, decl} (st : 'a) d : 'a =
    case mapfold {kind = fn k => fn st => S.Continue (k, kind (k, st)),
                  con = fn c => fn st => S.Continue (c, con (c, st)),
                  exp = fn e => fn st => S.Continue (e, exp (e, st)),
                  sgn_item = fn sgi => fn st => S.Continue (sgi, sgn_item (sgi, st)),
                  sgn = fn s => fn st => S.Continue (s, sgn (s, st)),
                  str = fn str' => fn st => S.Continue (str', str (str', st)),
                  decl = fn d => fn st => S.Continue (d, decl (d, st))} d st of
        S.Continue (_, st) => st
      | S.Return _ => raise Fail "ElabUtil.Decl.fold: Impossible"

end

structure File = struct

fun maxName ds = foldl (fn (d, count) => Int.max (maxNameDecl d, count)) 0 ds

and maxNameDecl (d, _) =
    case d of
        DCon (_, n, _, _) => n
      | DDatatype dts =>
        foldl (fn ((_, n, _, ns), max) =>
                  foldl (fn ((_, n', _), m) => Int.max (n', m))
                        (Int.max (n, max)) ns) 0 dts
      | DDatatypeImp (_, n1, n2, _, _, _, ns) =>
        foldl (fn ((_, n', _), m) => Int.max (n', m))
              (Int.max (n1, n2)) ns
      | DVal (_, n, _, _) => n
      | DValRec vis => foldl (fn ((_, n, _, _), count) => Int.max (n, count)) 0 vis
      | DStr (_, n, sgn, str) => Int.max (n, Int.max (maxNameSgn sgn, maxNameStr str))
      | DSgn (_, n, sgn) => Int.max (n, maxNameSgn sgn)
      | DFfiStr (_, n, sgn) => Int.max (n, maxNameSgn sgn)
      | DConstraint _ => 0
      | DExport _ => 0
      | DTable (n1, _, n2, _, _, _, _, _) => Int.max (n1, n2)
      | DSequence (n1, _, n2) => Int.max (n1, n2)
      | DView (n1, _, n2, _, _) => Int.max (n1, n2)
      | DDatabase _ => 0
      | DCookie (n1, _, n2, _) => Int.max (n1, n2)
      | DStyle (n1, _, n2) => Int.max (n1, n2)
      | DTask _ => 0
      | DPolicy _ => 0
      | DOnError _ => 0
      | DFfi (_, n, _, _) => n
and maxNameStr (str, _) =
    case str of
        StrConst ds => maxName ds
      | StrVar n => n
      | StrProj (str, _) => maxNameStr str
      | StrFun (_, n, dom, ran, str) => foldl Int.max n [maxNameSgn dom, maxNameSgn ran, maxNameStr str]
      | StrApp (str1, str2) => Int.max (maxNameStr str1, maxNameStr str2)
      | StrError => 0

and maxNameSgn (sgn, _) =
    case sgn of
        SgnConst sgis => foldl (fn (sgi, count) => Int.max (maxNameSgi sgi, count)) 0 sgis
      | SgnVar n => n
      | SgnFun (_, n, dom, ran) => Int.max (n, Int.max (maxNameSgn dom, maxNameSgn ran))
      | SgnWhere (sgn, _, _, _) => maxNameSgn sgn
      | SgnProj (n, _, _) => n
      | SgnError => 0

and maxNameSgi (sgi, _) =
    case sgi of
        SgiConAbs (_, n, _) => n
      | SgiCon (_, n, _, _) => n
      | SgiDatatype dts =>
        foldl (fn ((_, n, _, ns), max) =>
                  foldl (fn ((_, n', _), m) => Int.max (n', m))
                        (Int.max (n, max)) ns) 0 dts
      | SgiDatatypeImp (_, n1, n2, _, _, _, ns) =>
        foldl (fn ((_, n', _), m) => Int.max (n', m))
              (Int.max (n1, n2)) ns
      | SgiVal (_, n, _) => n
      | SgiStr (_, _, n, sgn) => Int.max (n, maxNameSgn sgn)
      | SgiSgn (_, n, sgn) => Int.max (n, maxNameSgn sgn)
      | SgiConstraint _ => 0
      | SgiClassAbs (_, n, _) => n
      | SgiClass (_, n, _, _) => n

fun findDecl pred file =
    let
        fun decl d =
            let
                val r = case #1 d of
                            DStr (_, _, _, s) => str s
                          | _ => NONE
            in
                case r of
                    NONE => if pred d then SOME d else NONE
                  | _ => r
            end

        and str s =
            case #1 s of
                StrConst ds => ListUtil.search decl ds
              | StrFun (_, _, _, _, s) => str s
              | StrApp (s1, s2) =>
                (case str s1 of
                     NONE => str s2
                   | r => r)
              | _ => NONE
    in
        ListUtil.search decl file
    end
              
end

end