summaryrefslogtreecommitdiff
path: root/src/mono_reduce.sml
blob: 060759545a4cc80280df1202aaf1a11b6e4d2604 (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
(* Copyright (c) 2008, 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.
 *)

(* Simplify a Mono program algebraically *)

structure MonoReduce :> MONO_REDUCE = struct

open Mono

structure E = MonoEnv
structure U = MonoUtil

structure IM = IntBinaryMap
structure IS = IntBinarySet


fun simpleTypeImpure tsyms =
    U.Typ.exists (fn TFun _ => true
                   | TDatatype (n, _) => IS.member (tsyms, n)
                   | _ => false)

fun simpleImpure (tsyms, syms) =
    U.Exp.existsB {typ = fn _ => false,
                   exp = fn (env, e) =>
                            case e of
                                EWrite _ => true
                              | EQuery _ => true
                              | EDml _ => true
                              | ENextval _ => true
                              | ESetval _ => true
                              | EFfiApp (m, x, _) => Settings.isEffectful (m, x) orelse Settings.isBenignEffectful (m, x)
                              | EServerCall _ => true
                              | ERecv _ => true
                              | ESleep _ => true
                              | ENamed n => IS.member (syms, n)
                              | ERel n =>
                                let
                                    val (_, t, _) = E.lookupERel env n
                                in
                                    simpleTypeImpure tsyms t
                                end
                              | _ => false,
                   bind = fn (env, b) =>
                             case b of
                                 U.Exp.RelE (x, t) => E.pushERel env x t NONE
                               | _ => env}

fun impure (e, _) =
    case e of
        EWrite _ => true
      | EQuery _ => true
      | EDml _ => true
      | ENextval _ => true
      | ESetval _ => true
      | EUnurlify (e, _, _) => impure e
      | EAbs _ => false

      | EPrim _ => false
      | ERel _ => false
      | ENamed _ => false
      | ECon (_, _, eo) => (case eo of NONE => false | SOME e => impure e)
      | ENone _ => false
      | ESome (_, e) => impure e
      | EFfi _ => false
      | EFfiApp (m, x, _) => Settings.isEffectful (m, x) orelse Settings.isBenignEffectful (m, x)
      | EApp ((EFfi _, _), _) => false
      | EApp _ => true

      | EUnop (_, e) => impure e
      | EBinop (_, _, e1, e2) => impure e1 orelse impure e2

      | ERecord xes => List.exists (fn (_, e, _) => impure e) xes
      | EField (e, _) => impure e

      | ECase (e, pes, _) => impure e orelse List.exists (fn (_, e) => impure e) pes

      | EError _ => true
      | EReturnBlob {blob = e1, mimeType = e2, ...} => impure e1 orelse impure e2
      | ERedirect (e, _) => impure e

      | EStrcat (e1, e2) => impure e1 orelse impure e2

      | ESeq (e1, e2) => impure e1 orelse impure e2
      | ELet (_, _, e1, e2) => impure e1 orelse impure e2

      | EClosure (_, es) => List.exists impure es
      | EJavaScript (_, e) => impure e
      | ESignalReturn e => impure e
      | ESignalBind (e1, e2) => impure e1 orelse impure e2
      | ESignalSource e => impure e
      | EServerCall _ => true
      | ERecv _ => true
      | ESleep _ => true
      | ESpawn _ => true

val liftExpInExp = Monoize.liftExpInExp

fun multiLift n e =
    case n of
        0 => e
      | _ => multiLift (n - 1) (liftExpInExp 0 e)

val subExpInExp' =
    U.Exp.mapB {typ = fn t => t,
                exp = fn (xn, rep) => fn e =>
                                  case e of
                                      ERel xn' =>
                                      (case Int.compare (xn', xn) of
                                           EQUAL => #1 rep
                                         | GREATER=> ERel (xn' - 1)
                                         | LESS => e)
                                    | _ => e,
                bind = fn ((xn, rep), U.Exp.RelE _) => (xn+1, liftExpInExp 0 rep)
                        | (ctx, _) => ctx}

fun subExpInExp (n, e1) e2 =
    let
        val r = subExpInExp' (n, e1) e2
    in
        (*Print.prefaces "subExpInExp" [("e1", MonoPrint.p_exp MonoEnv.empty e1),
                                      ("e2", MonoPrint.p_exp MonoEnv.empty e2),
                                      ("r", MonoPrint.p_exp MonoEnv.empty r)];*)
        r
    end

fun typ c = c

val swapExpVars =
    U.Exp.mapB {typ = fn t => t,
                exp = fn lower => fn e =>
                                     case e of
                                         ERel xn =>
                                         if xn = lower then
                                             ERel (lower + 1)
                                         else if xn = lower + 1 then
                                             ERel lower
                                         else
                                             e
                                       | _ => e,
                bind = fn (lower, U.Exp.RelE _) => lower+1
                        | (lower, _) => lower}

val swapExpVarsPat =
    U.Exp.mapB {typ = fn t => t,
                exp = fn (lower, len) => fn e =>
                                     case e of
                                         ERel xn =>
                                         if xn = lower then
                                             ERel (lower + len)
                                         else if xn >= lower + 1 andalso xn < lower + 1 + len then
                                             ERel (xn - 1)
                                         else
                                             e
                                       | _ => e,
                bind = fn ((lower, len), U.Exp.RelE _) => (lower+1, len)
                        | (st, _) => st}

datatype result = Yes of exp list | No | Maybe

fun match (env, p : pat, e : exp) =
    case (#1 p, #1 e) of
        (PWild, _) => Yes env
      | (PVar (x, t), _) => Yes (e :: env)

      | (PPrim (Prim.String s), EStrcat ((EPrim (Prim.String s'), _), _)) =>
        if String.isPrefix s' s then
            Maybe
        else
            No

      | (PPrim (Prim.String s), EStrcat (_, (EPrim (Prim.String s'), _))) =>
        if String.isSuffix s' s then
            Maybe
        else
            No

      | (PPrim p, EPrim p') =>
        if Prim.equal (p, p') then
            Yes env
        else
            No

      | (PCon (_, PConVar n1, NONE), ECon (_, PConVar n2, NONE)) =>
        if n1 = n2 then
            Yes env
        else
            No

      | (PCon (_, PConVar n1, SOME p), ECon (_, PConVar n2, SOME e)) =>
        if n1 = n2 then
            match (env, p, e)
        else
            No

      | (PCon (_, PConFfi {mod = m1, con = con1, ...}, NONE), ECon (_, PConFfi {mod = m2, con = con2, ...}, NONE)) =>
        if m1 = m2 andalso con1 = con2 then
            Yes env
        else
            No

      | (PCon (_, PConFfi {mod = m1, con = con1, ...}, SOME ep), ECon (_, PConFfi {mod = m2, con = con2, ...}, SOME e)) =>
        if m1 = m2 andalso con1 = con2 then
            match (env, p, e)
        else
            No

      | (PRecord xps, ERecord xes) =>
        let
            fun consider (xps, env) =
                case xps of
                    [] => Yes env
                  | (x, p, _) :: rest =>
                    case List.find (fn (x', _, _) => x' = x) xes of
                        NONE => No
                      | SOME (_, e, _) =>
                        case match (env, p, e) of
                            No => No
                          | Maybe => Maybe
                          | Yes env => consider (rest, env)
        in
            consider (xps, env)
        end

      | (PNone _, ENone _) => Yes env
      | (PNone _, ESome _) => No
      | (PSome (_, p), ESome (_, e)) => match (env, p, e)
      | (PSome _, ENone _) => No

      | _ => Maybe

datatype event =
         WritePage
       | ReadDb
       | WriteDb
       | ReadCookie
       | WriteCookie
       | UseRel
       | Unsure
       | Abort

fun p_event e =
    let
        open Print.PD
    in
        case e of
            WritePage => string "WritePage"
          | ReadDb => string "ReadDb"
          | WriteDb => string "WriteDb"
          | ReadCookie => string "ReadCookie"
          | WriteCookie => string "WriteCookie"
          | UseRel => string "UseRel"
          | Unsure => string "Unsure"
          | Abort => string "Abort"
    end

val p_events = Print.p_list p_event

fun patBinds (p, _) =
    case p of
        PWild => 0
      | PVar _ => 1
      | PPrim _ => 0
      | PCon (_, _, NONE) => 0
      | PCon (_, _, SOME p) => patBinds p
      | PRecord xpts => foldl (fn ((_, p, _), n) => n + patBinds p) 0 xpts
      | PNone _ => 0
      | PSome (_, p) => patBinds p

val countFree = U.Exp.foldB {typ = fn (_, n) => n,
                             exp = fn (x, e, n) =>
                                      case e of
                                          ERel x' => if x = x' then n + 1 else n
                                        | _ => n,
                             bind = fn (n, b) =>
                                       case b of
                                           U.Exp.RelE _ => n + 1
                                     | _ => n}

val freeInAbs = U.Exp.existsB {typ = fn _ => false,
                               exp = fn (n, e) =>
                                        case e of
                                            EAbs (_, _, _, b) => countFree n 0 b > 0
                                          | EJavaScript (_, b) => countFree n 0 b > 0
                                          | _ => false,
                               bind = fn (n, b) =>
                                         case b of
                                             U.Exp.RelE _ => n + 1
                                           | _ => n} 0

fun reduce file =
    let
        val (timpures, impures, absCounts) =
            foldl (fn ((d, _), (timpures, impures, absCounts)) =>
                      let
                          fun countAbs (e, _) =
                              case e of
                                  EAbs (_, _, _, e) => 1 + countAbs e
                                | _ => 0
                      in
                          case d of
                              DDatatype dts =>
                              (if List.exists (fn (_, _, cs) =>
                                                  List.exists (fn (_, _, NONE) => false
                                                                | (_, _, SOME t) => simpleTypeImpure timpures t) cs)
                                              dts then
                                   IS.addList (timpures, map #2 dts)
                               else
                                   timpures,
                               impures,
                               absCounts)
                            | DVal (_, n, _, e, _) =>
                              (timpures,
                               if simpleImpure (timpures, impures) E.empty e then
                                   IS.add (impures, n)
                               else
                                   impures,
                               IM.insert (absCounts, n, countAbs e))
                            | DValRec vis =>
                              (timpures,
                               if List.exists (fn (_, _, _, e, _) => simpleImpure (timpures, impures) E.empty e) vis then
                                   foldl (fn ((_, n, _, _, _), impures) =>
                                             IS.add (impures, n)) impures vis
                               else
                                   impures,
                               foldl (fn ((x, n, _, e, _), absCounts) =>
                                         IM.insert (absCounts, n, countAbs e))
                                     absCounts vis)
                            | _ => (timpures, impures, absCounts)
                      end)
                  (IS.empty, IS.empty, IM.empty) file

        val uses = U.File.fold {typ = fn (_, m) => m,
                                exp = fn (e, m) =>
                                         case e of
                                             ENamed n => IM.insert (m, n, 1 + Option.getOpt (IM.find (m, n), 0))
                                           | _ => m,
                                decl = fn (_, m) => m}
                               IM.empty file

        val size = U.Exp.fold {typ = fn (_, n) => n,
                               exp = fn (_, n) => n + 1} 0

        val functionInside' = U.Typ.exists (fn c => case c of
                                                        TFun _ => true
                                                      | _ => false)
                              
        fun functionInside t =
            case #1 t of
                TFun (t1, t2) => functionInside' t1 orelse functionInside t2
              | _ => functionInside' t

        fun mayInline (n, e, t, s) =
            case IM.find (uses, n) of
                NONE => false
              | SOME count => count <= 1
                              orelse size e <= Settings.getMonoInline ()
                              orelse functionInside t
                              orelse Settings.checkAlwaysInline s

        fun summarize d (e, _) =
            let
                val s =
                    case e of
                        EPrim _ => []
                      | ERel n => if n = d then [UseRel] else []
                      | ENamed _ => []
                      | ECon (_, _, NONE) => []
                      | ECon (_, _, SOME e) => summarize d e
                      | ENone _ => []
                      | ESome (_, e) => summarize d e
                      | EFfi _ => []
                      | EFfiApp ("Basis", "get_cookie", [e]) =>
                        summarize d e @ [ReadCookie]
                      | EFfiApp ("Basis", "set_cookie", es) =>
                        List.concat (map (summarize d) es) @ [WriteCookie]
                      | EFfiApp ("Basis", "clear_cookie", es) =>
                        List.concat (map (summarize d) es) @ [WriteCookie]
                      | EFfiApp (m, x, es) =>
                        if Settings.isEffectful (m, x) orelse Settings.isBenignEffectful (m, x) then
                            List.concat (map (summarize d) es) @ [if m = "Basis" andalso String.isSuffix "_w" x then
                                                                      WritePage
                                                                  else
                                                                      Unsure]
                        else
                            List.concat (map (summarize d) es)
                      | EApp ((EFfi _, _), e) => summarize d e
                      | EApp _ =>
                        let
                            fun unravel (e, passed, ls) =
                                case e of
                                    ENamed n =>
                                    let
                                        val ls = rev ls
                                    in
                                        if IS.member (impures, n) then
                                            case IM.find (absCounts, n) of
                                                NONE => [Unsure]
                                              | SOME len =>
                                                if passed < len then
                                                    ls
                                                else
                                                    ls @ [Unsure]
                                        else
                                            ls
                                    end
                                  | ERel n => List.revAppend (ls,
                                                              if n = d then
                                                                  [UseRel, Unsure]
                                                              else
                                                                  [Unsure])
                                  | EApp (f, x) =>
                                    unravel (#1 f, passed + 1, List.revAppend (summarize d x,
                                                                               ls))
                                  | EError _ => [Abort]
                                  | _ => [Unsure]
                        in
                            unravel (e, 0, [])
                        end

                      | EAbs _ => []

                      | EUnop (_, e) => summarize d e
                      | EBinop (_, _, e1, e2) => summarize d e1 @ summarize d e2

                      | ERecord xets => List.concat (map (summarize d o #2) xets)
                      | EField (e, _) => summarize d e

                      | ECase (e, pes, _) =>
                        let
                            val lss = map (fn (p, e) => summarize (d + patBinds p) e) pes

                            fun splitRel ls acc =
                                case ls of
                                    [] => (acc, false, ls)
                                  | UseRel :: ls  => (acc, true, ls)
                                  | v :: ls => splitRel ls (v :: acc)

                            val (pre, used, post) = foldl (fn (ls, (pre, used, post)) =>
                                                              let
                                                                  val (pre', used', post') = splitRel ls []
                                                              in
                                                                  (pre' @ pre, used' orelse used, post' @ post)
                                                              end)
                                                    ([], false, []) lss
                        in
                            summarize d e
                            @ pre
                            @ (if used then [UseRel] else [])
                            @ post
                        end
                      | EStrcat (e1, e2) => summarize d e1 @ summarize d e2

                      | EError (e, _) => summarize d e @ [Abort]
                      | EReturnBlob {blob = e1, mimeType = e2, ...} => summarize d e1 @ summarize d e2 @ [Abort]
                      | ERedirect (e, _) => summarize d e @ [Abort]

                      | EWrite e => summarize d e @ [WritePage]
                                    
                      | ESeq (e1, e2) => summarize d e1 @ summarize d e2
                      | ELet (_, _, e1, e2) => summarize d e1 @ summarize (d + 1) e2

                      | EClosure (_, es) => List.concat (map (summarize d) es)

                      | EQuery {query, body, initial, ...} =>
                        List.concat [summarize d query,
                                     summarize d initial,
                                     [ReadDb],
                                     summarize (d + 2) body]

                      | EDml (e, _) => summarize d e @ [WriteDb]
                      | ENextval e => summarize d e @ [WriteDb]
                      | ESetval (e1, e2) => summarize d e1 @ summarize d e2 @ [WriteDb]
                      | EUnurlify (e, _, _) => summarize d e
                      | EJavaScript (_, e) => summarize d e
                      | ESignalReturn e => summarize d e
                      | ESignalBind (e1, e2) => summarize d e1 @ summarize d e2
                      | ESignalSource e => summarize d e

                      | EServerCall (e, _, _) => summarize d e @ [Unsure]
                      | ERecv (e, _) => summarize d e @ [Unsure]
                      | ESleep e => summarize d e @ [Unsure]
                      | ESpawn e => summarize d e @ [Unsure]
            in
                (*Print.prefaces "Summarize"
                               [("e", MonoPrint.p_exp MonoEnv.empty (e, ErrorMsg.dummySpan)),
                                ("d", Print.PD.string (Int.toString d)),
                                ("s", p_events s)];*)
                s
            end

        val impure = fn env => fn e =>
                        simpleImpure (timpures, impures) env e andalso impure e
                        andalso not (List.null (summarize ~1 e))

        fun exp env e =
            let
                (*val () = Print.prefaces "exp" [("e", MonoPrint.p_exp env (e, ErrorMsg.dummySpan))]*)

                fun doLet (x, t, e', b) =
                    let
                        fun doSub () =
                            let
                                val r = subExpInExp (0, e') b
                            in
                                (*Print.prefaces "doSub" [("e'", MonoPrint.p_exp env e'),
                                                        ("b", MonoPrint.p_exp (E.pushERel env x t NONE) b),
                                                        ("r", MonoPrint.p_exp env r)];*)
                                #1 (reduceExp env r)
                            end

                        fun trySub () =
                            ((*Print.prefaces "trySub"
                                            [("e", MonoPrint.p_exp env (e, ErrorMsg.dummySpan))];*)
                             case t of
                                 (TFfi ("Basis", "string"), _) => doSub ()
                               | (TSignal _, _) => e
                               | _ =>
                                 case e' of
                                     (ECase _, _) => e
                                   | _ => doSub ())
                    in
                        if impure env e' then
                            let
                                val effs_e' = summarize 0 e'
                                val effs_e' = List.filter (fn x => x <> UseRel) effs_e'
                                val effs_b = summarize 0 b

                                (*val () = Print.fprefaces outf "Try"
                                                        [(*("e", MonoPrint.p_exp env (e, ErrorMsg.dummySpan)),*)
                                                         ("e'", MonoPrint.p_exp env e'),
                                                         ("b", MonoPrint.p_exp (E.pushERel env x t NONE) b),
                                                         ("e'_eff", p_events effs_e'),
                                                         ("b_eff", p_events effs_b)]*)

                                fun does eff = List.exists (fn eff' => eff' = eff) effs_e'
                                val writesPage = does WritePage
                                val readsDb = does ReadDb
                                val writesDb = does WriteDb
                                val readsCookie = does ReadCookie
                                val writesCookie = does ReadCookie

                                fun verifyUnused eff =
                                    case eff of
                                        UseRel => false
                                      | _ => true

                                fun verifyCompatible effs =
                                    case effs of
                                        [] => false
                                      | eff :: effs =>
                                        case eff of
                                            Unsure => false
                                          | UseRel => List.all verifyUnused effs
                                          | WritePage => not writesPage andalso verifyCompatible effs
                                          | ReadDb => not writesDb andalso verifyCompatible effs
                                          | WriteDb => not writesDb andalso not readsDb andalso verifyCompatible effs
                                          | ReadCookie => not writesCookie andalso verifyCompatible effs
                                          | WriteCookie => not writesCookie andalso not readsCookie
                                                           andalso verifyCompatible effs
                                          | Abort => true
                            in
                                (*Print.prefaces "verifyCompatible"
                                                 [("e'", MonoPrint.p_exp env e'),
                                                  ("b", MonoPrint.p_exp (E.pushERel env x t NONE) b),
                                                  ("effs_e'", Print.p_list p_event effs_e'),
                                                  ("effs_b", Print.p_list p_event effs_b)];*)
                                if (List.null effs_e'
                                    orelse (List.all (fn eff => eff <> Unsure) effs_e'
                                            andalso verifyCompatible effs_b)
                                    orelse (case effs_b of
                                                UseRel :: effs => List.all verifyUnused effs
                                              | _ => false))
                                   andalso countFree 0 0 b = 1
                                   andalso not (freeInAbs b) then
                                    trySub ()
                                else
                                    e
                            end
                        else
                            trySub ()
                    end

                val r =
                    case e of
                        ERel n =>
                        (case E.lookupERel env n of
                             (_, _, SOME e') => #1 e'
                           | _ => e)
                      | ENamed n =>
                        (case E.lookupENamed env n of
                             (_, _, SOME e', _) => ((*Print.prefaces "Switch" [("n", Print.PD.string (Int.toString n)),
                                                                               ("e'", MonoPrint.p_exp env e')];*)
                                                    #1 e')
                           | _ => e)

                      | EApp ((EAbs (x, t, _, e1), loc), e2) =>
                        ((*Print.prefaces "Considering" [("e1", MonoPrint.p_exp (E.pushERel env x t NONE) e1),
                                                       ("e2", MonoPrint.p_exp env e2),
                                                       ("sub", MonoPrint.p_exp env (reduceExp env (subExpInExp (0, e2) e1)))];*)
                         if impure env e2 orelse countFree 0 0 e1 > 1 then
                             #1 (reduceExp env (ELet (x, t, e2, e1), loc))
                         else
                             #1 (reduceExp env (subExpInExp (0, e2) e1)))

                      | ECase (e', pes, {disc, result}) =>
                        let
                            fun push () =
                                case result of
                                    (TFun (dom, result), loc) =>
                                    let
                                        fun safe (e, _) =
                                            case e of
                                                EAbs _ => true
                                              | EError _ => true
                                              | _ => false
                                    in
                                        if List.all (safe o #2) pes then
                                            EAbs ("y", dom, result,
                                                  (ECase (liftExpInExp 0 e',
                                                          map (fn (p, (EAbs (_, _, _, e), _)) =>
                                                                  (p, swapExpVarsPat (0, patBinds p) e)
                                                                | (p, (EError (e, (TFun (_, t), _)), loc)) =>
                                                                  (p, (EError (e, t), loc))
                                                                | _ => raise Fail "MonoReduce ECase") pes,
                                                          {disc = disc, result = result}), loc))
                                        else
                                            e
                                    end
                                  | _ => e

                            fun search pes =
                                case pes of
                                    [] => push ()
                                  | (p, body) :: pes =>
                                    case match ([], p, e') of
                                        No => search pes
                                      | Maybe => push ()
                                      | Yes subs =>
                                        let
                                            val (body, remaining) =
                                                foldl (fn (e, (body, remaining)) =>
                                                          (subExpInExp (0, multiLift remaining e) body, remaining - 1))
                                                      (body, length subs - 1) subs
                                            val r = reduceExp (E.patBinds env p) body
                                        in
                                            (*Print.preface ("subs", Print.p_list (MonoPrint.p_exp env) subs);*)
                                            (*Print.prefaces "ECase"
                                                           [("old", MonoPrint.p_exp env body),
                                                            ("body", MonoPrint.p_exp env body),
                                                            ("r", MonoPrint.p_exp env r)];*)
                                            #1 r
                                        end
                        in
                            if impure env e' then
                                e
                            else
                                search pes
                        end

                      | EField ((ERecord xes, _), x) =>
                        (case List.find (fn (x', _, _) => x' = x) xes of
                             SOME (_, e, _) => #1 e
                           | NONE => e)

                      | ELet (x1, t1, (ELet (x2, t2, e1, b1), loc), b2) =>
                        let
                            val e' = (ELet (x2, t2, e1,
                                            (ELet (x1, t1, b1,
                                                   liftExpInExp 1 b2), loc)), loc)
                        in
                            (*Print.prefaces "ELet commute" [("e", MonoPrint.p_exp env (e, loc)),
                                                             ("e'", MonoPrint.p_exp env e')];*)
                            #1 (reduceExp env e')
                        end
                      | EApp ((ELet (x, t, e, b), loc), e') =>
                        #1 (reduceExp env (ELet (x, t, e,
                                                 (EApp (b, liftExpInExp 0 e'), loc)), loc))

                      | ELet (x, t, e', b as (EAbs (x', t' as (TRecord [], _), ran, e''), loc)) =>
                        if impure env e' then
                            doLet (x, t, e', b)
                        else
                            EAbs (x', t', ran, reduceExp (E.pushERel env x' t' NONE)
                                                         (ELet (x, t, liftExpInExp 0 e', swapExpVars 0 e''), loc))

                      | ELet (x, t, e', b) => doLet (x, t, e', b)

                      | EStrcat ((EPrim (Prim.String s1), _), (EPrim (Prim.String s2), _)) =>
                        EPrim (Prim.String (s1 ^ s2))

                      | ESignalBind ((ESignalReturn e1, loc), e2) =>
                        #1 (reduceExp env (EApp (e2, e1), loc))

                      | _ => e
            in
                (*Print.prefaces "exp'" [("e", MonoPrint.p_exp env (e, ErrorMsg.dummySpan)),
                                       ("r", MonoPrint.p_exp env (r, ErrorMsg.dummySpan))];*)
                r
            end

        and bind (env, b) =
            case b of
                U.Decl.Datatype (x, n, xncs) => E.pushDatatype env x n xncs
              | U.Decl.RelE (x, t) => E.pushERel env x t NONE
              | U.Decl.NamedE (x, n, t, eo, s) =>
                let
                    val eo = case eo of
                                 NONE => NONE
                               | SOME e => if mayInline (n, e, t, s) then
                                               SOME e
                                           else
                                               NONE
                in
                    E.pushENamed env x n t (Option.map (reduceExp env) eo) s
                end

        and reduceExp env = U.Exp.mapB {typ = typ, exp = exp, bind = bind} env

        fun decl env d = ((*Print.preface ("d", MonoPrint.p_decl env (d, ErrorMsg.dummySpan));*)
                          d)
    in
        U.File.mapB {typ = typ, exp = exp, decl = decl, bind = bind} E.empty file
    end

end