about summary refs log blame commit diff stats
path: root/html/057immutable.cc.html
blob: 4d3b51fcda3d19ae39ecdba7e8f15aede1a5138b (plain) (tree)
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

























































































































































































































































































































































































































































































































































































































                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Mu - 057immutable.cc</title>
<meta name="Generator" content="Vim/7.4">
<meta name="plugin-version" content="vim7.4_v2">
<meta name="syntax" content="cpp">
<meta name="settings" content="use_css,pre_wrap,no_foldcolumn,expand_tabs,prevent_copy=">
<meta name="colorscheme" content="minimal">
<style type="text/css">
<!--
pre { white-space: pre-wrap; font-family: monospace; color: #eeeeee; background-color: #080808; }
body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color: #080808; }
* { font-size: 12pt; font-size: 1em; }
.Constant { color: #00a0a0; }
.cSpecial { color: #008000; }
.traceContains { color: #008000; }
.Comment { color: #9090ff; }
.Delimiter { color: #800080; }
.Special { color: #c00000; }
.Identifier { color: #fcb165; }
.Normal { color: #eeeeee; background-color: #080808; padding-bottom: 1px; }
.Todo { color: #000000; background-color: #ffff00; padding-bottom: 1px; }
-->
</style>

<script type='text/javascript'>
<!--

-->
</script>
</head>
<body>
<pre id='vimCodeElement'>
<span class="Comment">//: Ingredients of a recipe are meant to be immutable unless they're also</span>
<span class="Comment">//: products. This layer will start enforcing this check.</span>
<span class="Comment">//:</span>
<span class="Comment">//: One hole for now: variables in surrounding spaces are implicitly mutable.</span>

<span class="Delimiter">:(scenario can_modify_ingredients_that_are_also_products)</span>
<span class="Comment"># mutable container</span>
def main [
  local-scope
  <span class="Normal">p</span>:point<span class="Special"> &lt;- </span>merge <span class="Constant">34</span><span class="Delimiter">,</span> <span class="Constant">35</span>
  p<span class="Special"> &lt;- </span>foo p
]
def foo p:point <span class="Delimiter">-&gt;</span> p:point [
  local-scope
  load-ingredients
  p<span class="Special"> &lt;- </span>put p<span class="Delimiter">,</span> x:offset<span class="Delimiter">,</span> <span class="Constant">34</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario can_modify_ingredients_that_are_also_products_2)</span>
def main [
  local-scope
  <span class="Normal">p</span>:address:point<span class="Special"> &lt;- </span><span class="Normal">new</span> point:type
  p<span class="Special"> &lt;- </span>foo p
]
<span class="Comment"># mutable address to container</span>
def foo p:address:point <span class="Delimiter">-&gt;</span> p:address:point [
  local-scope
  load-ingredients
  *p<span class="Special"> &lt;- </span>put *p<span class="Delimiter">,</span> x:offset<span class="Delimiter">,</span> <span class="Constant">34</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario can_modify_ingredients_that_are_also_products_3)</span>
def main [
  local-scope
  <span class="Normal">p</span>:address:array:number<span class="Special"> &lt;- </span><span class="Normal">new</span> number:type<span class="Delimiter">,</span> <span class="Constant">3</span>
  p<span class="Special"> &lt;- </span>foo p
]
<span class="Comment"># mutable address</span>
def foo p:address:array:number <span class="Delimiter">-&gt;</span> p:address:array:number [
  local-scope
  load-ingredients
  *p<span class="Special"> &lt;- </span>put-index *p<span class="Delimiter">,</span> <span class="Constant">0</span><span class="Delimiter">,</span> <span class="Constant">34</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario ignore_literal_ingredients_for_immutability_checks)</span>
def main [
  local-scope
  <span class="Normal">p</span>:address:d1<span class="Special"> &lt;- </span><span class="Normal">new</span> d1:type
  <span class="Normal">q</span>:number<span class="Special"> &lt;- </span>foo p
]
def foo p:address:d1 <span class="Delimiter">-&gt;</span> q:number [
  local-scope
  load-ingredients
  <span class="Normal">x</span>:address:d1<span class="Special"> &lt;- </span><span class="Normal">new</span> d1:type
  *x<span class="Special"> &lt;- </span>put *x<span class="Delimiter">,</span> p:offset<span class="Delimiter">,</span> <span class="Constant">34</span>  <span class="Comment"># ignore this 'p'</span>
  reply <span class="Constant">36</span>
]
container d1 [
  <span class="Normal">p</span>:number
  <span class="Normal">q</span>:number
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario cannot_modify_immutable_ingredients)</span>
<span class="Special">% Hide_errors = true;</span>
def main [
  local-scope
  <span class="Normal">x</span>:address:number<span class="Special"> &lt;- </span><span class="Normal">new</span> number:type
  foo x
]
<span class="Comment"># immutable address to primitive</span>
def foo x:address:number [
  local-scope
  load-ingredients
  *x<span class="Special"> &lt;- </span>copy <span class="Constant">34</span>
]
<span class="traceContains">+error: foo: cannot modify 'x' in instruction '*x &lt;- copy 34' because it's an ingredient of recipe foo but not also a product</span>

<span class="Delimiter">:(scenario cannot_modify_immutable_containers)</span>
<span class="Special">% Hide_errors = true;</span>
def main [
  local-scope
  <span class="Normal">x</span>:point-number<span class="Special"> &lt;- </span>merge <span class="Constant">34</span><span class="Delimiter">,</span> <span class="Constant">35</span><span class="Delimiter">,</span> <span class="Constant">36</span>
  foo x
]
<span class="Comment"># immutable container</span>
def foo x:point-number [
  local-scope
  load-ingredients
  <span class="Comment"># copy an element: ok</span>
  <span class="Normal">y</span>:point<span class="Special"> &lt;- </span>get x<span class="Delimiter">,</span> xy:offset
  <span class="Comment"># modify the element: boom</span>
  <span class="Comment"># This could be ok if y contains no addresses, but we're not going to try to be that smart.</span>
  <span class="Comment"># It also makes the rules easier to reason about. If it's just an ingredient, just don't try to change it.</span>
  y<span class="Special"> &lt;- </span>put y<span class="Delimiter">,</span> x:offset<span class="Delimiter">,</span> <span class="Constant">37</span>
]
<span class="traceContains">+error: foo: cannot modify 'y' in instruction 'y &lt;- put y, x:offset, 37' because that would modify 'x' which is an ingredient of recipe foo but not also a product</span>

<span class="Delimiter">:(scenario can_modify_immutable_pointers)</span>
def main [
  local-scope
  <span class="Normal">x</span>:address:number<span class="Special"> &lt;- </span><span class="Normal">new</span> number:type
  foo x
]
def foo x:address:number [
  local-scope
  load-ingredients
  <span class="Comment"># modify the address, not the payload</span>
  x<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario can_modify_immutable_pointers_but_not_their_payloads)</span>
<span class="Special">% Hide_errors = true;</span>
def main [
  local-scope
  <span class="Normal">x</span>:address:number<span class="Special"> &lt;- </span><span class="Normal">new</span> number:type
  foo x
]
def foo x:address:number [
  local-scope
  load-ingredients
  <span class="Comment"># modify address; ok</span>
  x<span class="Special"> &lt;- </span><span class="Normal">new</span> number:type
  <span class="Comment"># modify payload: boom</span>
  <span class="Comment"># this could be ok, but we're not going to try to be that smart</span>
  *x<span class="Special"> &lt;- </span>copy <span class="Constant">34</span>
]
<span class="traceContains">+error: foo: cannot modify 'x' in instruction '*x &lt;- copy 34' because it's an ingredient of recipe foo but not also a product</span>

<span class="Delimiter">:(scenario cannot_call_mutating_recipes_on_immutable_ingredients)</span>
<span class="Special">% Hide_errors = true;</span>
def main [
  local-scope
  <span class="Normal">p</span>:address:point<span class="Special"> &lt;- </span><span class="Normal">new</span> point:type
  foo p
]
def foo p:address:point [
  local-scope
  load-ingredients
  bar p
]
def bar p:address:point <span class="Delimiter">-&gt;</span> p:address:point [
  local-scope
  load-ingredients
  <span class="Comment"># p could be modified here, but it doesn't have to be, it's already marked</span>
  <span class="Comment"># mutable in the header</span>
]
<span class="traceContains">+error: foo: cannot modify 'p' in instruction 'bar p' because it's an ingredient of recipe foo but not also a product</span>

<span class="Delimiter">:(scenario cannot_modify_copies_of_immutable_ingredients)</span>
<span class="Special">% Hide_errors = true;</span>
def main [
  local-scope
  <span class="Normal">p</span>:address:point<span class="Special"> &lt;- </span><span class="Normal">new</span> point:type
  foo p
]
def foo p:address:point [
  local-scope
  load-ingredients
  <span class="Normal">q</span>:address:point<span class="Special"> &lt;- </span>copy p
  *q<span class="Special"> &lt;- </span>put *q<span class="Delimiter">,</span> x:offset<span class="Delimiter">,</span> <span class="Constant">34</span>
]
<span class="traceContains">+error: foo: cannot modify 'q' in instruction '*q &lt;- put *q, x:offset, 34' because that would modify p which is an ingredient of recipe foo but not also a product</span>

<span class="Delimiter">:(scenario can_modify_copies_of_mutable_ingredients)</span>
def main [
  local-scope
  <span class="Normal">p</span>:address:point<span class="Special"> &lt;- </span><span class="Normal">new</span> point:type
  foo p
]
def foo p:address:point <span class="Delimiter">-&gt;</span> p:address:point [
  local-scope
  load-ingredients
  <span class="Normal">q</span>:address:point<span class="Special"> &lt;- </span>copy p
  *q<span class="Special"> &lt;- </span>put *q<span class="Delimiter">,</span> x:offset<span class="Delimiter">,</span> <span class="Constant">34</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario cannot_modify_address_inside_immutable_ingredients)</span>
<span class="Special">% Hide_errors = true;</span>
container foo [
  <span class="Normal">x</span>:address:array:number  <span class="Comment"># contains an address</span>
]
def main [
  <span class="Comment"># don't run anything</span>
]
def foo a:address:foo [
  local-scope
  load-ingredients
  <span class="Normal">x</span>:address:array:number<span class="Special"> &lt;- </span>get *a<span class="Delimiter">,</span> x:offset  <span class="Comment"># just a regular get of the container</span>
  *x<span class="Special"> &lt;- </span>put-index *x<span class="Delimiter">,</span> <span class="Constant">0</span><span class="Delimiter">,</span> <span class="Constant">34</span>  <span class="Comment"># but then a put-index on the result</span>
]
<span class="traceContains">+error: foo: cannot modify 'x' in instruction '*x &lt;- put-index *x, 0, 34' because that would modify a which is an ingredient of recipe foo but not also a product</span>

<span class="Delimiter">:(scenario cannot_modify_address_inside_immutable_ingredients_2)</span>
container foo [
  <span class="Normal">x</span>:address:array:number  <span class="Comment"># contains an address</span>
]
def main [
  <span class="Comment"># don't run anything</span>
]
def foo a:address:foo [
  local-scope
  load-ingredients
  <span class="Normal">b</span>:foo<span class="Special"> &lt;- </span>merge <span class="Constant">0</span>
  <span class="Comment"># modify b, completely unrelated to immutable ingredient a</span>
  <span class="Normal">x</span>:address:array:number<span class="Special"> &lt;- </span>get b<span class="Delimiter">,</span> x:offset
  *x<span class="Special"> &lt;- </span>put-index *x<span class="Delimiter">,</span> <span class="Constant">0</span><span class="Delimiter">,</span> <span class="Constant">34</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario cannot_modify_address_inside_immutable_ingredients_3)</span>
<span class="Special">% Hide_errors = true;</span>
container foo [
  <span class="Normal">x</span>:number
]
def main [
  <span class="Comment"># don't run anything</span>
]
def foo a:address:array:address:number [
  local-scope
  load-ingredients
  <span class="Normal">x</span>:address:number<span class="Special"> &lt;- </span>index *a<span class="Delimiter">,</span> <span class="Constant">0</span>  <span class="Comment"># just a regular index of the array</span>
  *x<span class="Special"> &lt;- </span>copy <span class="Constant">34</span>  <span class="Comment"># but then modify the result</span>
]
<span class="traceContains">+error: foo: cannot modify 'x' in instruction '*x &lt;- copy 34' because that would modify a which is an ingredient of recipe foo but not also a product</span>

<span class="Delimiter">:(scenario cannot_modify_address_inside_immutable_ingredients_4)</span>
container foo [
  <span class="Normal">x</span>:address:array:number  <span class="Comment"># contains an address</span>
]
def main [
  <span class="Comment"># don't run anything</span>
]
def foo a:address:array:address:number [
  local-scope
  load-ingredients
  <span class="Normal">b</span>:address:array:address:number<span class="Special"> &lt;- </span><span class="Normal">new</span> <span class="Delimiter">{(</span>address number<span class="Delimiter">)</span>: type<span class="Delimiter">},</span> <span class="Constant">3</span>
  <span class="Comment"># modify b, completely unrelated to immutable ingredient a</span>
  <span class="Normal">x</span>:address:number<span class="Special"> &lt;- </span>index *b<span class="Delimiter">,</span> <span class="Constant">0</span>
  *x<span class="Special"> &lt;- </span>copy <span class="Constant">34</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario can_traverse_immutable_ingredients)</span>
container test-list [
  <span class="Normal">next</span>:address:test-list
]
def main [
  local-scope
  <span class="Normal">p</span>:address:test-list<span class="Special"> &lt;- </span><span class="Normal">new</span> test-list:type
  foo p
]
def foo p:address:test-list [
  local-scope
  load-ingredients
  <span class="Normal">p2</span>:address:test-list<span class="Special"> &lt;- </span>bar p
]
def bar x:address:test-list <span class="Delimiter">-&gt;</span> y:address:test-list [
  local-scope
  load-ingredients
  y<span class="Special"> &lt;- </span>get *x<span class="Delimiter">,</span> next:offset
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario treat_optional_ingredients_as_mutable)</span>
def main [
  <span class="Normal">k</span>:address:number<span class="Special"> &lt;- </span><span class="Normal">new</span> number:type
  test k
]
<span class="Comment"># recipe taking an immutable address ingredient</span>
def test k:address:number [
  local-scope
  load-ingredients
  foo k
]
<span class="Comment"># ..calling a recipe with an optional address ingredient</span>
def foo <span class="Delimiter">-&gt;</span> [
  local-scope
  load-ingredients
  <span class="Normal">k</span>:address:number<span class="Delimiter">,</span> found?:boolean<span class="Special"> &lt;- </span>next-ingredient
  <span class="Comment"># we don't further check k for immutability, but assume it's mutable</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(scenario treat_optional_ingredients_as_mutable_2)</span>
<span class="Special">% Hide_errors = true;</span>
def main [
  local-scope
  <span class="Normal">p</span>:address:point<span class="Special"> &lt;- </span><span class="Normal">new</span> point:type
  foo p
]
def foo p:address:point [
  local-scope
  load-ingredients
  bar p
]
def bar [
  local-scope
  load-ingredients
  <span class="Normal">p</span>:address:point<span class="Special"> &lt;- </span>next-ingredient  <span class="Comment"># optional ingredient; assumed to be mutable</span>
]
<span class="traceContains">+error: foo: cannot modify 'p' in instruction 'bar p' because it's an ingredient of recipe foo but not also a product</span>

<span class="Comment">//: when checking for immutable ingredients, remember to take space into account</span>
<span class="Delimiter">:(scenario check_space_of_reagents_in_immutability_checks)</span>
def main [
  <span class="Normal">a</span>:address:array:location<span class="Special"> &lt;- </span><span class="Normal">new</span>-closure
  <span class="Normal">b</span>:address:number<span class="Special"> &lt;- </span><span class="Normal">new</span> number:type
  run-closure b:address:number<span class="Delimiter">,</span> a:address:array:location
]
def <span class="Normal">new</span>-closure [
  <span class="Normal">new</span>-<span class="Normal">default</span>-space
  <span class="Normal">x</span>:address:number<span class="Special"> &lt;- </span><span class="Normal">new</span> number:type
  <span class="Identifier">return</span> <span class="Normal">default</span>-space
]
def run-closure x:address:number<span class="Delimiter">,</span> s:address:array:location [
  local-scope
  load-ingredients
  <span class="Constant">0</span>:address:array:location/names:<span class="Normal">new</span>-closure<span class="Special"> &lt;- </span>copy s
  <span class="Comment"># different space; always mutable</span>
  *x:address:number/space:<span class="Constant">1</span><span class="Special"> &lt;- </span>copy <span class="Constant">34</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(before &quot;End Transforms&quot;)</span>
Transform<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>check_immutable_ingredients<span class="Delimiter">);</span>  <span class="Comment">// idempotent</span>

<span class="Delimiter">:(code)</span>
<span class="Normal">void</span> check_immutable_ingredients<span class="Delimiter">(</span>recipe_ordinal r<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Comment">// to ensure an address reagent isn't modified, it suffices to show that</span>
  <span class="Comment">//   a) we never write to its contents directly,</span>
  <span class="Comment">//   b) we never call 'put' or 'put-index' on it, and</span>
  <span class="Comment">//   c) any non-primitive recipe calls in the body aren't returning it as a product</span>
  <span class="Normal">const</span> recipe&amp; caller = get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">);</span>
  trace<span class="Delimiter">(</span><span class="Constant">9991</span><span class="Delimiter">,</span> <span class="Constant">&quot;transform&quot;</span><span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;--- check mutability of ingredients in recipe &quot;</span> &lt;&lt; caller<span class="Delimiter">.</span>name &lt;&lt; end<span class="Delimiter">();</span>
  <span class="Normal">if</span> <span class="Delimiter">(</span>!caller<span class="Delimiter">.</span>has_header<span class="Delimiter">)</span> <span class="Identifier">return</span><span class="Delimiter">;</span>  <span class="Comment">// skip check for old-style recipes calling next-ingredient directly</span>
  <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>ingredients<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    <span class="Normal">const</span> reagent&amp; current_ingredient = caller<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>is_present_in_products<span class="Delimiter">(</span>caller<span class="Delimiter">,</span> current_ingredient<span class="Delimiter">.</span>name<span class="Delimiter">))</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>  <span class="Comment">// not expected to be immutable</span>
    <span class="Comment">// End Immutable Ingredients Special-cases</span>
    set&lt;reagent&gt; immutable_vars<span class="Delimiter">;</span>
    immutable_vars<span class="Delimiter">.</span>insert<span class="Delimiter">(</span>current_ingredient<span class="Delimiter">);</span>
    <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>steps<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
      <span class="Normal">const</span> instruction&amp; inst = caller<span class="Delimiter">.</span>steps<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
      check_immutable_ingredient_in_instruction<span class="Delimiter">(</span>inst<span class="Delimiter">,</span> immutable_vars<span class="Delimiter">,</span> current_ingredient<span class="Delimiter">.</span>name<span class="Delimiter">,</span> caller<span class="Delimiter">);</span>
      update_aliases<span class="Delimiter">(</span>inst<span class="Delimiter">,</span> immutable_vars<span class="Delimiter">);</span>
    <span class="Delimiter">}</span>
  <span class="Delimiter">}</span>
<span class="Delimiter">}</span>

<span class="Normal">void</span> update_aliases<span class="Delimiter">(</span><span class="Normal">const</span> instruction&amp; inst<span class="Delimiter">,</span> set&lt;reagent&gt;&amp; current_ingredient_and_aliases<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  set&lt;<span class="Normal">int</span>&gt; current_ingredient_indices = ingredient_indices<span class="Delimiter">(</span>inst<span class="Delimiter">,</span> current_ingredient_and_aliases<span class="Delimiter">);</span>
  <span class="Normal">if</span> <span class="Delimiter">(</span>!contains_key<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> inst<span class="Delimiter">.</span>operation<span class="Delimiter">))</span> <span class="Delimiter">{</span>
    <span class="Comment">// primitive recipe</span>
    <span class="Normal">switch</span> <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>operation<span class="Delimiter">)</span> <span class="Delimiter">{</span>
      <span class="Normal">case</span> COPY:
        <span class="Normal">for</span> <span class="Delimiter">(</span>set&lt;<span class="Normal">int</span>&gt;::iterator p = current_ingredient_indices<span class="Delimiter">.</span>begin<span class="Delimiter">();</span> p != current_ingredient_indices<span class="Delimiter">.</span>end<span class="Delimiter">();</span> ++p<span class="Delimiter">)</span>
          current_ingredient_and_aliases<span class="Delimiter">.</span>insert<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>*p<span class="Delimiter">).</span>name<span class="Delimiter">);</span>
        <span class="Identifier">break</span><span class="Delimiter">;</span>
      <span class="Normal">case</span> GET:
      <span class="Normal">case</span> INDEX:
      <span class="Normal">case</span> MAYBE_CONVERT:
        <span class="Comment">// current_ingredient_indices can only have 0 or one value</span>
        <span class="Normal">if</span> <span class="Delimiter">(</span>!current_ingredient_indices<span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Delimiter">{</span>
          <span class="Normal">if</span> <span class="Delimiter">(</span>is_mu_address<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">))</span> || is_mu_container<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">))</span> || is_mu_exclusive_container<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span>
            current_ingredient_and_aliases<span class="Delimiter">.</span>insert<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">));</span>
        <span class="Delimiter">}</span>
        <span class="Identifier">break</span><span class="Delimiter">;</span>
      <span class="Normal">default</span>: <span class="Identifier">break</span><span class="Delimiter">;</span>
    <span class="Delimiter">}</span>
  <span class="Delimiter">}</span>
  <span class="Normal">else</span> <span class="Delimiter">{</span>
    <span class="Comment">// defined recipe</span>
    set&lt;<span class="Normal">int</span>&gt; contained_in_product_indices = scan_contained_in_product_indices<span class="Delimiter">(</span>inst<span class="Delimiter">,</span> current_ingredient_indices<span class="Delimiter">);</span>
    <span class="Normal">for</span> <span class="Delimiter">(</span>set&lt;<span class="Normal">int</span>&gt;::iterator p = contained_in_product_indices<span class="Delimiter">.</span>begin<span class="Delimiter">();</span> p != contained_in_product_indices<span class="Delimiter">.</span>end<span class="Delimiter">();</span> ++p<span class="Delimiter">)</span> <span class="Delimiter">{</span>
      <span class="Normal">if</span> <span class="Delimiter">(</span>*p &lt; SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">))</span>
        current_ingredient_and_aliases<span class="Delimiter">.</span>insert<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>*p<span class="Delimiter">));</span>
    <span class="Delimiter">}</span>
  <span class="Delimiter">}</span>
<span class="Delimiter">}</span>

set&lt;<span class="Normal">int</span>&gt; scan_contained_in_product_indices<span class="Delimiter">(</span><span class="Normal">const</span> instruction&amp; inst<span class="Delimiter">,</span> set&lt;<span class="Normal">int</span>&gt;&amp; ingredient_indices<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  set&lt;reagent&gt; selected_ingredients<span class="Delimiter">;</span>
  <span class="Normal">const</span> recipe&amp; callee = get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> inst<span class="Delimiter">.</span>operation<span class="Delimiter">);</span>
  <span class="Normal">for</span> <span class="Delimiter">(</span>set&lt;<span class="Normal">int</span>&gt;::iterator p = ingredient_indices<span class="Delimiter">.</span>begin<span class="Delimiter">();</span> p != ingredient_indices<span class="Delimiter">.</span>end<span class="Delimiter">();</span> ++p<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>*p &gt;= SIZE<span class="Delimiter">(</span>callee<span class="Delimiter">.</span>ingredients<span class="Delimiter">))</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>  <span class="Comment">// optional immutable ingredient</span>
    selected_ingredients<span class="Delimiter">.</span>insert<span class="Delimiter">(</span>callee<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>*p<span class="Delimiter">));</span>
  <span class="Delimiter">}</span>
  set&lt;<span class="Normal">int</span>&gt; result<span class="Delimiter">;</span>
  <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>callee<span class="Delimiter">.</span>products<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    <span class="Normal">const</span> reagent&amp; current_product = callee<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
    <span class="Comment">// </span><span class="Todo">TODO</span>
    <span class="Normal">const</span> string_tree* contained_in_name = property<span class="Delimiter">(</span>current_product<span class="Delimiter">,</span> <span class="Constant">&quot;contained-in&quot;</span><span class="Delimiter">);</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>contained_in_name &amp;&amp; selected_ingredients<span class="Delimiter">.</span>find<span class="Delimiter">(</span>contained_in_name<span class="Delimiter">-&gt;</span>value<span class="Delimiter">)</span> != selected_ingredients<span class="Delimiter">.</span>end<span class="Delimiter">())</span>
      result<span class="Delimiter">.</span>insert<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
  <span class="Delimiter">}</span>
  <span class="Identifier">return</span> result<span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="Delimiter">:(scenarios transform)</span>
<span class="Delimiter">:(scenario immutability_infects_contained_in_variables)</span>
<span class="Special">% Hide_errors = true;</span>
container test-list [
  <span class="Normal">value</span>:number
  <span class="Normal">next</span>:address:test-list
]
def main [
  local-scope
  <span class="Normal">p</span>:address:test-list<span class="Special"> &lt;- </span><span class="Normal">new</span> test-list:type
  foo p
]
def foo p:address:test-list [  <span class="Comment"># p is immutable</span>
  local-scope
  load-ingredients
  <span class="Normal">p2</span>:address:test-list<span class="Special"> &lt;- </span>test-next p  <span class="Comment"># p2 is immutable</span>
  *p2<span class="Special"> &lt;- </span>put *p2<span class="Delimiter">,</span> value:offset<span class="Delimiter">,</span> <span class="Constant">34</span>
]
def test-next x:address:test-list <span class="Delimiter">-&gt;</span> y:address:test-list/contained-in:x [
  local-scope
  load-ingredients
  y<span class="Special"> &lt;- </span>get *x<span class="Delimiter">,</span> next:offset
]
<span class="traceContains">+error: foo: cannot modify 'p2' in instruction '*p2 &lt;- put *p2, value:offset, 34' because that would modify p which is an ingredient of recipe foo but not also a product</span>

<span class="Delimiter">:(code)</span>
<span class="Normal">void</span> check_immutable_ingredient_in_instruction<span class="Delimiter">(</span><span class="Normal">const</span> instruction&amp; inst<span class="Delimiter">,</span> <span class="Normal">const</span> set&lt;reagent&gt;&amp; current_ingredient_and_aliases<span class="Delimiter">,</span> <span class="Normal">const</span> string&amp; original_ingredient_name<span class="Delimiter">,</span> <span class="Normal">const</span> recipe&amp; caller<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Comment">// first check if the instruction is directly modifying something it shouldn't</span>
  <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>has_property<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">),</span> <span class="Constant">&quot;lookup&quot;</span><span class="Delimiter">)</span>
        &amp;&amp; current_ingredient_and_aliases<span class="Delimiter">.</span>find<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">))</span> != current_ingredient_and_aliases<span class="Delimiter">.</span>end<span class="Delimiter">())</span> <span class="Delimiter">{</span>
      string current_product_name = inst<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>name<span class="Delimiter">;</span>
      <span class="Normal">if</span> <span class="Delimiter">(</span>current_product_name == original_ingredient_name<span class="Delimiter">)</span>
        raise &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;cannot modify '&quot;</span> &lt;&lt; current_product_name &lt;&lt; <span class="Constant">&quot;' in instruction '&quot;</span> &lt;&lt; to_original_string<span class="Delimiter">(</span>inst<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;' because it's an ingredient of recipe &quot;</span> &lt;&lt; caller<span class="Delimiter">.</span>name &lt;&lt; <span class="Constant">&quot; but not also a product</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
      <span class="Normal">else</span>
        raise &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;cannot modify '&quot;</span> &lt;&lt; current_product_name &lt;&lt; <span class="Constant">&quot;' in instruction '&quot;</span> &lt;&lt; to_original_string<span class="Delimiter">(</span>inst<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;' because that would modify &quot;</span> &lt;&lt; original_ingredient_name &lt;&lt; <span class="Constant">&quot; which is an ingredient of recipe &quot;</span> &lt;&lt; caller<span class="Delimiter">.</span>name &lt;&lt; <span class="Constant">&quot; but not also a product</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
      <span class="Identifier">return</span><span class="Delimiter">;</span>
    <span class="Delimiter">}</span>
  <span class="Delimiter">}</span>
  <span class="Comment">// check if there's any indirect modification going on</span>
  set&lt;<span class="Normal">int</span>&gt; current_ingredient_indices = ingredient_indices<span class="Delimiter">(</span>inst<span class="Delimiter">,</span> current_ingredient_and_aliases<span class="Delimiter">);</span>
  <span class="Normal">if</span> <span class="Delimiter">(</span>current_ingredient_indices<span class="Delimiter">.</span>empty<span class="Delimiter">())</span> <span class="Identifier">return</span><span class="Delimiter">;</span>  <span class="Comment">// ingredient not found in call</span>
  <span class="Normal">for</span> <span class="Delimiter">(</span>set&lt;<span class="Normal">int</span>&gt;::iterator p = current_ingredient_indices<span class="Delimiter">.</span>begin<span class="Delimiter">();</span> p != current_ingredient_indices<span class="Delimiter">.</span>end<span class="Delimiter">();</span> ++p<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    <span class="Normal">const</span> <span class="Normal">int</span> current_ingredient_index = *p<span class="Delimiter">;</span>
    reagent current_ingredient = inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>current_ingredient_index<span class="Delimiter">);</span>
    canonize_type<span class="Delimiter">(</span>current_ingredient<span class="Delimiter">);</span>
    <span class="Normal">const</span> string&amp; current_ingredient_name = current_ingredient<span class="Delimiter">.</span>name<span class="Delimiter">;</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>!contains_key<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> inst<span class="Delimiter">.</span>operation<span class="Delimiter">))</span> <span class="Delimiter">{</span>
      <span class="Comment">// primitive recipe</span>
      <span class="Comment">// we got here only because we got an instruction with an implicit product, and the instruction didn't explicitly spell it out</span>
      <span class="Comment">//    put x, y:offset, z</span>
      <span class="Comment">// instead of</span>
      <span class="Comment">//    x &lt;- put x, y:offset, z</span>
      <span class="Normal">if</span> <span class="Delimiter">(</span>inst<span class="Delimiter">.</span>operation == PUT || inst<span class="Delimiter">.</span>operation == PUT_INDEX<span class="Delimiter">)</span> <span class="Delimiter">{</span>
        <span class="Normal">if</span> <span class="Delimiter">(</span>current_ingredient_index == <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
          <span class="Normal">if</span> <span class="Delimiter">(</span>current_ingredient_name == original_ingredient_name<span class="Delimiter">)</span>
            raise &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;cannot modify '&quot;</span> &lt;&lt; current_ingredient_name &lt;&lt; <span class="Constant">&quot;' in instruction '&quot;</span> &lt;&lt; to_original_string<span class="Delimiter">(</span>inst<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;' because it's an ingredient of recipe &quot;</span> &lt;&lt; caller<span class="Delimiter">.</span>name &lt;&lt; <span class="Constant">&quot; but not also a product</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
          <span class="Normal">else</span>
            raise &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;cannot modify '&quot;</span> &lt;&lt; current_ingredient_name &lt;&lt; <span class="Constant">&quot;' in instruction '&quot;</span> &lt;&lt; to_original_string<span class="Delimiter">(</span>inst<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;' because that would modify '&quot;</span> &lt;&lt; original_ingredient_name &lt;&lt; <span class="Constant">&quot;' which is an ingredient of recipe &quot;</span> &lt;&lt; caller<span class="Delimiter">.</span>name &lt;&lt; <span class="Constant">&quot; but not also a product</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
        <span class="Delimiter">}</span>
      <span class="Delimiter">}</span>
    <span class="Delimiter">}</span>
    <span class="Normal">else</span> <span class="Delimiter">{</span>
      <span class="Comment">// defined recipe</span>
      <span class="Normal">if</span> <span class="Delimiter">(</span>is_modified_in_recipe<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>operation<span class="Delimiter">,</span> current_ingredient_index<span class="Delimiter">,</span> caller<span class="Delimiter">))</span> <span class="Delimiter">{</span>
        <span class="Normal">if</span> <span class="Delimiter">(</span>current_ingredient_name == original_ingredient_name<span class="Delimiter">)</span>
          raise &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;cannot modify '&quot;</span> &lt;&lt; current_ingredient_name &lt;&lt; <span class="Constant">&quot;' in instruction '&quot;</span> &lt;&lt; to_original_string<span class="Delimiter">(</span>inst<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;' because it's an ingredient of recipe &quot;</span> &lt;&lt; caller<span class="Delimiter">.</span>name &lt;&lt; <span class="Constant">&quot; but not also a product</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
        <span class="Normal">else</span>
          raise &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;cannot modify '&quot;</span> &lt;&lt; current_ingredient_name &lt;&lt; <span class="Constant">&quot;' in instruction '&quot;</span> &lt;&lt; to_original_string<span class="Delimiter">(</span>inst<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;' because that would modify '&quot;</span> &lt;&lt; original_ingredient_name &lt;&lt; <span class="Constant">&quot;' which is an ingredient of recipe &quot;</span> &lt;&lt; caller<span class="Delimiter">.</span>name &lt;&lt; <span class="Constant">&quot; but not also a product</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
      <span class="Delimiter">}</span>
    <span class="Delimiter">}</span>
  <span class="Delimiter">}</span>
<span class="Delimiter">}</span>

<span class="Normal">bool</span> is_modified_in_recipe<span class="Delimiter">(</span>recipe_ordinal r<span class="Delimiter">,</span> <span class="Normal">int</span> ingredient_index<span class="Delimiter">,</span> <span class="Normal">const</span> recipe&amp; caller<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Normal">const</span> recipe&amp; callee = get<span class="Delimiter">(</span>Recipe<span class="Delimiter">,</span> r<span class="Delimiter">);</span>
  <span class="Normal">if</span> <span class="Delimiter">(</span>!callee<span class="Delimiter">.</span>has_header<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    raise &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;can't check mutability of ingredients in recipe &quot;</span> &lt;&lt; callee<span class="Delimiter">.</span>name &lt;&lt; <span class="Constant">&quot; because it uses 'next-ingredient' directly, rather than a recipe header.</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
    <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  <span class="Normal">if</span> <span class="Delimiter">(</span>ingredient_index &gt;= SIZE<span class="Delimiter">(</span>callee<span class="Delimiter">.</span>ingredients<span class="Delimiter">))</span> <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>  <span class="Comment">// optional immutable ingredient</span>
  <span class="Identifier">return</span> is_present_in_products<span class="Delimiter">(</span>callee<span class="Delimiter">,</span> callee<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>ingredient_index<span class="Delimiter">).</span>name<span class="Delimiter">);</span>
<span class="Delimiter">}</span>

<span class="Normal">bool</span> is_present_in_products<span class="Delimiter">(</span><span class="Normal">const</span> recipe&amp; callee<span class="Delimiter">,</span> <span class="Normal">const</span> string&amp; ingredient_name<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>callee<span class="Delimiter">.</span>products<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>callee<span class="Delimiter">.</span>products<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>name == ingredient_name<span class="Delimiter">)</span>
      <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="Normal">bool</span> is_present_in_ingredients<span class="Delimiter">(</span><span class="Normal">const</span> recipe&amp; callee<span class="Delimiter">,</span> <span class="Normal">const</span> string&amp; ingredient_name<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>callee<span class="Delimiter">.</span>ingredients<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>callee<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">).</span>name == ingredient_name<span class="Delimiter">)</span>
      <span class="Identifier">return</span> <span class="Constant">true</span><span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  <span class="Identifier">return</span> <span class="Constant">false</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>

set&lt;<span class="Normal">int</span>&gt; ingredient_indices<span class="Delimiter">(</span><span class="Normal">const</span> instruction&amp; inst<span class="Delimiter">,</span> <span class="Normal">const</span> set&lt;reagent&gt;&amp; ingredient_names<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  set&lt;<span class="Normal">int</span>&gt; result<span class="Delimiter">;</span>
  <span class="Normal">for</span> <span class="Delimiter">(</span><span class="Normal">int</span> i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; SIZE<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">);</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>is_literal<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">)))</span> <span class="Identifier">continue</span><span class="Delimiter">;</span>
    <span class="Normal">if</span> <span class="Delimiter">(</span>ingredient_names<span class="Delimiter">.</span>find<span class="Delimiter">(</span>inst<span class="Delimiter">.</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">))</span> != ingredient_names<span class="Delimiter">.</span>end<span class="Delimiter">())</span>
      result<span class="Delimiter">.</span>insert<span class="Delimiter">(</span>i<span class="Delimiter">);</span>
  <span class="Delimiter">}</span>
  <span class="Identifier">return</span> result<span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="Comment">//: Sometimes you want to pass in two addresses, one pointing inside the</span>
<span class="Comment">//: other. For example, you want to delete a node from a linked list. You</span>
<span class="Comment">//: can't pass both pointers back out, because if a caller tries to make both</span>
<span class="Comment">//: identical then you can't tell which value will be written on the way out.</span>
<span class="Comment">//:</span>
<span class="Comment">//: Experimental solution: just tell mu that one points inside the other.</span>
<span class="Comment">//: This way we can return just one pointer as high up as necessary to capture</span>
<span class="Comment">//: all modifications performed by a recipe.</span>
<span class="Comment">//:</span>
<span class="Comment">//: We'll see if we end up wanting to abuse /contained-in for other reasons.</span>

<span class="Delimiter">:(scenarios transform)</span>
<span class="Delimiter">:(scenario can_modify_contained_in_addresses)</span>
container test-list [
  <span class="Normal">value</span>:number
  <span class="Normal">next</span>:address:test-list
]
def main [
  local-scope
  <span class="Normal">p</span>:address:test-list<span class="Special"> &lt;- </span><span class="Normal">new</span> test-list:type
  foo p
]
def foo p:address:test-list <span class="Delimiter">-&gt;</span> p:address:test-list [
  local-scope
  load-ingredients
  <span class="Normal">p2</span>:address:test-list<span class="Special"> &lt;- </span>test-next p
  p<span class="Special"> &lt;- </span>test-remove p2<span class="Delimiter">,</span> p
]
def test-next x:address:test-list <span class="Delimiter">-&gt;</span> y:address:test-list [
  local-scope
  load-ingredients
  y<span class="Special"> &lt;- </span>get *x<span class="Delimiter">,</span> next:offset
]
def test-remove x:address:test-list/contained-in:from<span class="Delimiter">,</span> from:address:test-list <span class="Delimiter">-&gt;</span> from:address:test-list [
  local-scope
  load-ingredients
  *x<span class="Special"> &lt;- </span>put *x<span class="Delimiter">,</span> value:offset<span class="Delimiter">,</span> <span class="Constant">34</span>  <span class="Comment"># can modify x</span>
]
$error: <span class="Constant">0</span>

<span class="Delimiter">:(before &quot;End Immutable Ingredients Special-cases&quot;)</span>
<span class="Normal">if</span> <span class="Delimiter">(</span>has_property<span class="Delimiter">(</span>current_ingredient<span class="Delimiter">,</span> <span class="Constant">&quot;contained-in&quot;</span><span class="Delimiter">))</span> <span class="Delimiter">{</span>
  <span class="Normal">const</span> string_tree* tmp = property<span class="Delimiter">(</span>current_ingredient<span class="Delimiter">,</span> <span class="Constant">&quot;contained-in&quot;</span><span class="Delimiter">);</span>
  <span class="Normal">if</span> <span class="Delimiter">(</span>tmp<span class="Delimiter">-&gt;</span>left || tmp<span class="Delimiter">-&gt;</span>right
      || !is_present_in_ingredients<span class="Delimiter">(</span>caller<span class="Delimiter">,</span> tmp<span class="Delimiter">-&gt;</span>value<span class="Delimiter">)</span>
      || !is_present_in_products<span class="Delimiter">(</span>caller<span class="Delimiter">,</span> tmp<span class="Delimiter">-&gt;</span>value<span class="Delimiter">))</span>
    raise &lt;&lt; maybe<span class="Delimiter">(</span>caller<span class="Delimiter">.</span>name<span class="Delimiter">)</span> &lt;&lt; <span class="Constant">&quot;/contained-in can only point to another ingredient+product, but got '&quot;</span> &lt;&lt; to_string<span class="Delimiter">(</span>property<span class="Delimiter">(</span>current_ingredient<span class="Delimiter">,</span> <span class="Constant">&quot;contained-in&quot;</span><span class="Delimiter">))</span> &lt;&lt; <span class="Constant">&quot;'</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
  <span class="Identifier">continue</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>
</pre>
</body>
</html>
<!-- vim: set foldmethod=manual : -->