aboutsummaryrefslogtreecommitdiffstats
path: root/erts/doc/src/absform.xml
blob: d77d9890572c1d3ba03e8aa595e2e6f15906b8ec (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE chapter SYSTEM "chapter.dtd">

<chapter>
  <header>
    <copyright>
      <year>2001</year><year>2018</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
      You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

      Unless required by applicable law or agreed to in writing, software
      distributed under the License is distributed on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      See the License for the specific language governing permissions and
      limitations under the License.

    </legalnotice>

    <title>The Abstract Format</title>
    <prepared>Arndt Jonasson</prepared>
    <responsible>Kenneth Lundin</responsible>
    <docno>1</docno>
    <approved></approved>
    <checked></checked>
    <date>2000-12-01</date>
    <rev>A</rev>
    <file>absform.xml</file>
  </header>
  <p>This section describes the standard representation of parse trees for Erlang
    programs as Erlang terms. This representation is known as the <em>abstract
    format</em>. Functions dealing with such parse trees are
    <seealso marker="compiler:compile#forms/1">
    <c>compile:forms/1,2</c></seealso> and functions in the following
    modules:</p>

  <list type="bulleted">
    <item><seealso marker="stdlib:epp">
      <c>epp(3)</c></seealso></item>
    <item><seealso marker="stdlib:erl_eval">
      <c>erl_eval(3)</c></seealso></item>
    <item><seealso marker="stdlib:erl_lint">
      <c>erl_lint(3)</c></seealso></item>
    <item><seealso marker="stdlib:erl_parse">
      <c>erl_parse(3)</c></seealso></item>
    <item><seealso marker="stdlib:erl_pp">
      <c>erl_pp(3)</c></seealso></item>
    <item><seealso marker="stdlib:io">
      <c>io(3)</c></seealso></item>
  </list>

  <p>The functions are also used as input and output for parse transforms, see
    the <seealso marker="compiler:compile"><c>compile(3)</c></seealso>
    module.</p>

  <p>We use the function <c>Rep</c> to denote the mapping from an Erlang source
    construct <c>C</c> to its abstract format representation <c>R</c>, and write
    <c>R = Rep(C)</c>.</p>

  <p>The word <c>LINE</c> in this section represents an integer, and denotes the
    number of the line in the source file where the construction occurred.
    Several instances of <c>LINE</c> in the same construction can denote
    different lines.</p>

  <p>As operators are not terms in their own right, when operators are
    mentioned below, the representation of an operator is to be taken to
    be the atom with a printname consisting of the same characters as the
    operator.</p>

  <section>
    <title>Module Declarations and Forms</title>
    <p>A module declaration consists of a sequence of forms, which are either
      function declarations or attributes.</p>

    <list type="bulleted">
      <item>
        <p>If D is a module declaration consisting of the forms
          <c>F_1</c>, ..., <c>F_k</c>, then
          Rep(D) = <c>[Rep(F_1), ..., Rep(F_k)]</c>.</p>
      </item>
      <item>
        <p>If F is an attribute <c>-export([Fun_1/A_1, ..., Fun_k/A_k])</c>,
          then Rep(F) =
          <c>{attribute,LINE,export,[{Fun_1,A_1}, ..., {Fun_k,A_k}]}</c>.</p>
      </item>
      <item>
        <p>If F is an attribute <c>-import(Mod,[Fun_1/A_1, ..., Fun_k/A_k])</c>,
          then Rep(F) =
          <c>{attribute,LINE,import,{Mod,[{Fun_1,A_1}, ...,
          {Fun_k,A_k}]}}</c>.</p>
      </item>
      <item>
        <p>If F is an attribute <c>-module(Mod)</c>, then
          Rep(F) = <c>{attribute,LINE,module,Mod}</c>.</p>
      </item>
      <item>
        <p>If F is an attribute <c>-file(File,Line)</c>, then
          Rep(F) = <c>{attribute,LINE,file,{File,Line}}</c>.</p>
      </item>
      <item>
        <p>If F is a function declaration <c>Name Fc_1 ; ... ; Name Fc_k</c>,
          where each <c>Fc_i</c> is a function clause with a pattern sequence of
          the same length <c>Arity</c>, then Rep(F) =
          <c>{function,LINE,Name,Arity,[Rep(Fc_1), ...,Rep(Fc_k)]}</c>.</p>
      </item>
      <item>
        <p>If F is a function specification <c>-Spec Name Ft_1; ...; Ft_k</c>,
          where <c>Spec</c> is either the atom <c>spec</c> or the atom
          <c>callback</c>, and each <c>Ft_i</c> is a possibly constrained
          function type with an argument sequence of the same length
          <c>Arity</c>, then Rep(F) =
          <c>{attribute,Line,Spec,{{Name,Arity},[Rep(Ft_1), ...,
          Rep(Ft_k)]}}</c>.</p>
      </item>
      <item>
        <p>If F is a function specification
          <c>-spec Mod:Name Ft_1; ...; Ft_k</c>, where each <c>Ft_i</c> is a
          possibly constrained function type with an argument sequence of the
          same length <c>Arity</c>, then Rep(F) =
          <c>{attribute,Line,spec,{{Mod,Name,Arity},[Rep(Ft_1), ...,
          Rep(Ft_k)]}}</c>.</p>
      </item>
      <item>
        <p>If F is a record declaration <c>-record(Name,{V_1, ..., V_k})</c>,
          where each <c>V_i</c> is a record field, then Rep(F) =
          <c>{attribute,LINE,record,{Name,[Rep(V_1), ..., Rep(V_k)]}}</c>.
          For Rep(V), see below.</p>
      </item>
      <item>
        <p>If F is a type declaration <c>-Type Name(V_1, ..., V_k) :: T</c>,
          where <c>Type</c> is either the atom <c>type</c> or the atom
          <c>opaque</c>, each <c>V_i</c> is a variable, and <c>T</c> is a type,
          then Rep(F) =
          <c>{attribute,LINE,Type,{Name,Rep(T),[Rep(V_1), ...,
          Rep(V_k)]}}</c>.</p>
      </item>
      <item>
        <p>If F is a wild attribute <c>-A(T)</c>, then
          Rep(F) = <c>{attribute,LINE,A,T}</c>.</p>
      </item>
    </list>

    <section>
      <title>Record Fields</title>
      <p>Each field in a record declaration can have an optional,
        explicit, default initializer expression, and an
        optional type.</p>

      <list type="bulleted">
        <item>
          <p>If V is <c>A</c>, then
            Rep(V) = <c>{record_field,LINE,Rep(A)}</c>.</p>
        </item>
        <item>
          <p>If V is <c>A = E</c>, where <c>E</c> is an expression, then
            Rep(V) = <c>{record_field,LINE,Rep(A),Rep(E)}</c>.</p>
        </item>
        <item>
          <p>If V is <c>A :: T</c>, where <c>T</c> is a type, then Rep(V) =
            <c>{typed_record_field,{record_field,LINE,Rep(A)},Rep(T)}</c>.</p>
        </item>
        <item>
          <p>If V is <c>A = E :: T</c>, where
            <c>E</c> is an expression and <c>T</c> is a type, then Rep(V) =
            <c>{typed_record_field,{record_field,LINE,Rep(A),Rep(E)},Rep(T)}</c>.
          </p>
        </item>
      </list>
    </section>

    <section>
      <title>Representation of Parse Errors and End-of-File</title>
      <p>In addition to the representations of forms, the list that represents
        a module declaration (as returned by functions in
        <seealso marker="stdlib:epp"><c>epp(3)</c></seealso> and
        <seealso marker="stdlib:erl_parse"><c>erl_parse(3)</c></seealso>)
        can contain the following:</p>

      <list type="bulleted">
        <item>
          <p>Tuples <c>{error,E}</c> and <c>{warning,W}</c>, denoting
            syntactically incorrect forms and warnings.
          </p>
        </item>
        <item>
          <p><c>{eof,LOCATION}</c>, denoting an end-of-stream
            encountered before a complete form had been parsed.
            The word <c>LOCATION</c> represents an integer, and denotes the
            number of the last line in the source file.
          </p>
        </item>
      </list>
    </section>
  </section>

  <section>
    <title>Atomic Literals</title>
    <p>There are five kinds of atomic literals, which are represented in the
      same way in patterns, expressions, and guards:</p>

    <list type="bulleted">
      <item>
        <p>If L is an atom literal, then Rep(L) = <c>{atom,LINE,L}</c>.</p>
      </item>
      <item>
        <p>If L is a character literal, then Rep(L) = <c>{char,LINE,L}</c>.</p>
      </item>
      <item>
        <p>If L is a float literal, then Rep(L) = <c>{float,LINE,L}</c>.</p>
      </item>
      <item>
        <p>If L is an integer literal, then
          Rep(L) = <c>{integer,LINE,L}</c>.</p>
      </item>
      <item>
        <p>If L is a string literal consisting of the characters
          <c>C_1</c>, ..., <c>C_k</c>, then
          Rep(L) = <c>{string,LINE,[C_1, ..., C_k]}</c>.</p>
      </item>
    </list>

    <p>Notice that negative integer and float literals do not occur as such;
      they are parsed as an application of the unary negation operator.</p>
  </section>

  <section>
    <title>Patterns</title>
    <p>If Ps is a sequence of patterns <c>P_1, ..., P_k</c>, then
      Rep(Ps) = <c>[Rep(P_1), ..., Rep(P_k)]</c>. Such sequences occur as the
      list of arguments to a function or fun.</p>

    <p>Individual patterns are represented as follows:</p>

    <list type="bulleted">
      <item>
        <p>If P is an atomic literal <c>L</c>, then Rep(P) = Rep(L).</p>
      </item>
      <item>
        <p>If P is a bitstring pattern
          <c>&lt;&lt;P_1:Size_1/TSL_1, ..., P_k:Size_k/TSL_k>></c>, where each
          <c>Size_i</c> is an expression that can be evaluated to an integer,
          and each <c>TSL_i</c> is a type specificer list, then Rep(P) =
          <c>{bin,LINE,[{bin_element,LINE,Rep(P_1),Rep(Size_1),Rep(TSL_1)},
          ..., {bin_element,LINE,Rep(P_k),Rep(Size_k),Rep(TSL_k)}]}</c>.
          For Rep(TSL), see below.
          An omitted <c>Size_i</c> is represented by <c>default</c>.
          An omitted <c>TSL_i</c> is represented by <c>default</c>.</p>
      </item>
      <item>
        <p>If P is a compound pattern <c>P_1 = P_2</c>, then Rep(P) =
          <c>{match,LINE,Rep(P_1),Rep(P_2)}</c>.</p>
      </item>
      <item>
        <p>If P is a cons pattern <c>[P_h | P_t]</c>, then Rep(P) =
          <c>{cons,LINE,Rep(P_h),Rep(P_t)}</c>.</p>
      </item>
      <item>
        <p>If P is a map pattern <c>#{A_1, ..., A_k}</c>, where each
          <c>A_i</c> is an association <c>P_i_1 := P_i_2</c>, then Rep(P) =
          <c>{map,LINE,[Rep(A_1), ..., Rep(A_k)]}</c>.
          For Rep(A), see below.</p>
      </item>
      <item>
        <p>If P is a nil pattern <c>[]</c>, then Rep(P) =
          <c>{nil,LINE}</c>.</p>
      </item>
      <item>
        <p>If P is an operator pattern <c>P_1 Op P_2</c>, where <c>Op</c> is a
          binary operator (this is either an occurrence of <c>++</c> applied to
          a literal string or character list, or an occurrence of an expression
          that can be evaluated to a number at compile time), then Rep(P) =
          <c>{op,LINE,Op,Rep(P_1),Rep(P_2)}</c>.</p>
      </item>
      <item>
        <p>If P is an operator pattern <c>Op P_0</c>, where <c>Op</c> is a
          unary operator (this is an occurrence of an expression that can be
          evaluated to a number at compile time), then Rep(P) =
          <c>{op,LINE,Op,Rep(P_0)}</c>.</p>
      </item>
      <item>
        <p>If P is a parenthesized pattern <c>( P_0 )</c>, then Rep(P) =
          <c>Rep(P_0)</c>, that is, parenthesized patterns cannot be
          distinguished from their bodies.</p>
      </item>
      <item>
        <p>If P is a record field index pattern <c>#Name.Field</c>,
          where <c>Field</c> is an atom, then Rep(P) =
          <c>{record_index,LINE,Name,Rep(Field)}</c>.</p>
      </item>
      <item>
        <p>If P is a record pattern <c>#Name{Field_1=P_1, ..., Field_k=P_k}</c>,
          where each <c>Field_i</c> is an atom or <c>_</c>, then Rep(P) =
          <c>{record,LINE,Name,[{record_field,LINE,Rep(Field_1),Rep(P_1)}, ...,
          {record_field,LINE,Rep(Field_k),Rep(P_k)}]}</c>.</p>
      </item>
      <item>
        <p>If P is a tuple pattern <c>{P_1, ..., P_k}</c>, then Rep(P) =
          <c>{tuple,LINE,[Rep(P_1), ..., Rep(P_k)]}</c>.</p>
      </item>
      <item>
        <p>If P is a universal pattern <c>_</c>, then Rep(P) =
          <c>{var,LINE,'_'}</c>.</p></item>
      <item>
        <p>If P is a variable pattern <c>V</c>, then Rep(P) =
          <c>{var,LINE,A}</c>, where A is an atom with a printname consisting
          of the same characters as <c>V</c>.</p>
      </item>
    </list>

    <p>Notice that every pattern has the same source form as some expression,
      and is represented in the same way as the corresponding expression.</p>
  </section>

  <section>
    <title>Expressions</title>
    <p>A body B is a non-empty sequence of expressions <c>E_1, ..., E_k</c>,
      and Rep(B) = <c>[Rep(E_1), ..., Rep(E_k)]</c>.</p>

    <p>An expression E is one of the following:</p>

    <list type="bulleted">
      <item>
        <p>If E is an atomic literal <c>L</c>, then Rep(E) = Rep(L).</p>
      </item>
      <item>
        <p>If E is a bitstring comprehension
          <c>&lt;&lt;E_0 || Q_1, ..., Q_k>></c>,
          where each <c>Q_i</c> is a qualifier, then Rep(E) =
          <c>{bc,LINE,Rep(E_0),[Rep(Q_1), ..., Rep(Q_k)]}</c>.
          For Rep(Q), see below.</p>
      </item>
      <item>
        <p>If E is a bitstring constructor
          <c>&lt;&lt;E_1:Size_1/TSL_1, ..., E_k:Size_k/TSL_k>></c>,
          where each <c>Size_i</c> is an expression and each
          <c>TSL_i</c> is a type specificer list, then Rep(E) =
          <c>{bin,LINE,[{bin_element,LINE,Rep(E_1),Rep(Size_1),Rep(TSL_1)},
          ..., {bin_element,LINE,Rep(E_k),Rep(Size_k),Rep(TSL_k)}]}</c>.
          For Rep(TSL), see below.
          An omitted <c>Size_i</c> is represented by <c>default</c>.
          An omitted <c>TSL_i</c> is represented by <c>default</c>.</p>
      </item>
      <item>
        <p>If E is a block expression <c>begin B end</c>,
          where <c>B</c> is a body, then Rep(E) =
          <c>{block,LINE,Rep(B)}</c>.</p>
      </item>
      <item>
        <p>If E is a case expression <c>case E_0 of Cc_1 ; ... ; Cc_k end</c>,
          where <c>E_0</c> is an expression and each <c>Cc_i</c> is a
          case clause, then Rep(E) =
          <c>{'case',LINE,Rep(E_0),[Rep(Cc_1), ..., Rep(Cc_k)]}</c>.</p>
      </item>
      <item>
        <p>If E is a catch expression <c>catch E_0</c>, then Rep(E) =
          <c>{'catch',LINE,Rep(E_0)}</c>.</p>
      </item>
      <item>
        <p>If E is a cons skeleton <c>[E_h | E_t]</c>, then Rep(E) =
          <c>{cons,LINE,Rep(E_h),Rep(E_t)}</c>.</p>
      </item>
      <item>
        <p>If E is a fun expression <c>fun Name/Arity</c>, then Rep(E) =
          <c>{'fun',LINE,{function,Name,Arity}}</c>.</p>
      </item>
      <item>
        <p>If E is a fun expression <c>fun Module:Name/Arity</c>, then Rep(E) =
          <c>{'fun',LINE,{function,Rep(Module),Rep(Name),Rep(Arity)}}</c>.
          (Before Erlang/OTP R15: Rep(E) =
          <c>{'fun',LINE,{function,Module,Name,Arity}}</c>.)</p>
      </item>
      <item>
        <p>If E is a fun expression <c>fun Fc_1 ; ... ; Fc_k end</c>,
          where each <c>Fc_i</c> is a function clause, then Rep(E) =
          <c>{'fun',LINE,{clauses,[Rep(Fc_1), ..., Rep(Fc_k)]}}</c>.</p>
      </item>
      <item>
        <p>If E is a fun expression <c>fun Name Fc_1 ; ... ; Name Fc_k end</c>,
          where <c>Name</c> is a variable and each
          <c>Fc_i</c> is a function clause, then Rep(E) =
          <c>{named_fun,LINE,Name,[Rep(Fc_1), ..., Rep(Fc_k)]}</c>.</p>
      </item>
      <item>
        <p>If E is a function call <c>E_0(E_1, ..., E_k)</c>, then Rep(E) =
          <c>{call,LINE,Rep(E_0),[Rep(E_1), ..., Rep(E_k)]}</c>.</p>
      </item>
      <item>
        <p>If E is a function call <c>E_m:E_0(E_1, ..., E_k)</c>, then Rep(E) =
          <c>{call,LINE,{remote,LINE,Rep(E_m),Rep(E_0)},[Rep(E_1), ...,
          Rep(E_k)]}</c>.</p>
      </item>
      <item>
        <p>If E is an if expression <c>if Ic_1 ; ... ; Ic_k  end</c>,
          where each <c>Ic_i</c> is an if clause, then Rep(E) =
          <c>{'if',LINE,[Rep(Ic_1), ..., Rep(Ic_k)]}</c>.</p>
      </item>
      <item>
        <p>If E is a list comprehension <c>[E_0 || Q_1, ..., Q_k]</c>,
          where each <c>Q_i</c> is a qualifier, then Rep(E) =
          <c>{lc,LINE,Rep(E_0),[Rep(Q_1), ..., Rep(Q_k)]}</c>.
          For Rep(Q), see below.</p>
      </item>
      <item>
        <p>If E is a map creation <c>#{A_1, ..., A_k}</c>,
          where each <c>A_i</c> is an association <c>E_i_1 => E_i_2</c>,
	  then Rep(E) = <c>{map,LINE,[Rep(A_1), ..., Rep(A_k)]}</c>.
          For Rep(A), see below.</p>
      </item>
      <item>
        <p>If E is a map update <c>E_0#{A_1, ..., A_k}</c>,
          where each <c>A_i</c> is an association <c>E_i_1 => E_i_2</c>
          or <c>E_i_1 := E_i_2</c>, then Rep(E) =
          <c>{map,LINE,Rep(E_0),[Rep(A_1), ..., Rep(A_k)]}</c>.
          For Rep(A), see below.</p>
      </item>
      <item>
        <p>If E is a match operator expression <c>P = E_0</c>,
          where <c>P</c> is a pattern, then Rep(E) =
          <c>{match,LINE,Rep(P),Rep(E_0)}</c>.</p>
      </item>
      <item>
        <p>If E is nil, <c>[]</c>, then Rep(E) = <c>{nil,LINE}</c>.</p>
      </item>
      <item>
        <p>If E is an operator expression <c>E_1 Op E_2</c>,
          where <c>Op</c> is a binary operator other than match operator
          <c>=</c>, then Rep(E) =
          <c>{op,LINE,Op,Rep(E_1),Rep(E_2)}</c>.</p>
      </item>
      <item>
        <p>If E is an operator expression <c>Op E_0</c>,
          where <c>Op</c> is a unary operator, then Rep(E) =
          <c>{op,LINE,Op,Rep(E_0)}</c>.</p>
      </item>
      <item>
        <p>If E is a parenthesized expression <c>( E_0 )</c>, then Rep(E) =
          <c>Rep(E_0)</c>, that is, parenthesized expressions cannot be
          distinguished from their bodies.</p>
      </item>
      <item>
        <p>If E is a receive expression <c>receive Cc_1 ; ... ; Cc_k end</c>,
          where each <c>Cc_i</c> is a case clause, then Rep(E) =
          <c>{'receive',LINE,[Rep(Cc_1), ..., Rep(Cc_k)]}</c>.</p>
      </item>
      <item>
        <p>If E is a receive expression
          <c>receive Cc_1 ; ... ; Cc_k after E_0 -> B_t end</c>,
          where each <c>Cc_i</c> is a case clause, <c>E_0</c> is an expression,
          and <c>B_t</c> is a body, then Rep(E) =
          <c>{'receive',LINE,[Rep(Cc_1), ...,
          Rep(Cc_k)],Rep(E_0),Rep(B_t)}</c>.</p>
      </item>
      <item>
        <p>If E is a record creation
          <c>#Name{Field_1=E_1, ..., Field_k=E_k}</c>,
          where each <c>Field_i</c> is an atom or <c>_</c>, then Rep(E) =
          <c>{record,LINE,Name,[{record_field,LINE,Rep(Field_1),Rep(E_1)},
          ..., {record_field,LINE,Rep(Field_k),Rep(E_k)}]}</c>.</p>
      </item>
      <item>
        <p>If E is a record field access <c>E_0#Name.Field</c>,
          where <c>Field</c> is an atom, then Rep(E) =
          <c>{record_field,LINE,Rep(E_0),Name,Rep(Field)}</c>.</p>
      </item>
      <item>
        <p>If E is a record field index <c>#Name.Field</c>,
          where <c>Field</c> is an atom, then Rep(E) =
          <c>{record_index,LINE,Name,Rep(Field)}</c>.</p></item>
      <item>
        <p>If E is a record update
          <c>E_0#Name{Field_1=E_1, ..., Field_k=E_k}</c>,
          where each <c>Field_i</c> is an atom, then Rep(E) =
          <c>{record,LINE,Rep(E_0),Name,[{record_field,LINE,Rep(Field_1),Rep(E_1)},
      ..., {record_field,LINE,Rep(Field_k),Rep(E_k)}]}</c>.</p>
      </item>
      <item>
        <p>If E is a tuple skeleton <c>{E_1, ..., E_k}</c>, then Rep(E) =
          <c>{tuple,LINE,[Rep(E_1), ..., Rep(E_k)]}</c>.</p>
      </item>
      <item>
        <p>If E is a try expression <c>try B catch Tc_1 ; ... ; Tc_k end</c>,
          where <c>B</c> is a body and each <c>Tc_i</c> is a catch clause,
          then Rep(E) =
          <c>{'try',LINE,Rep(B),[],[Rep(Tc_1), ..., Rep(Tc_k)],[]}</c>.</p>
      </item>
      <item>
        <p>If E is a try expression
          <c>try B of Cc_1 ; ... ; Cc_k catch Tc_1 ; ... ; Tc_n end</c>,
          where <c>B</c> is a body, each <c>Cc_i</c> is a case clause, and
          each <c>Tc_j</c> is a catch clause, then Rep(E) =
          <c>{'try',LINE,Rep(B),[Rep(Cc_1), ..., Rep(Cc_k)],[Rep(Tc_1), ...,
          Rep(Tc_n)],[]}</c>.</p>
      </item>
      <item>
        <p>If E is a try expression <c>try B after A end</c>,
          where <c>B</c> and <c>A</c> are bodies, then Rep(E) =
          <c>{'try',LINE,Rep(B),[],[],Rep(A)}</c>.</p>
      </item>
      <item>
        <p>If E is a try expression
          <c>try B of Cc_1 ; ... ; Cc_k after A end</c>,
          where <c>B</c> and <c>A</c> are a bodies,
          and each <c>Cc_i</c> is a case clause, then Rep(E) =
          <c>{'try',LINE,Rep(B),[Rep(Cc_1), ...,
          Rep(Cc_k)],[],Rep(A)}</c>.</p>
      </item>
      <item>
        <p>If E is a try expression
          <c>try B catch Tc_1 ; ... ; Tc_k after A end</c>,
          where <c>B</c> and <c>A</c> are bodies,
          and each <c>Tc_i</c> is a catch clause, then Rep(E) =
          <c>{'try',LINE,Rep(B),[],[Rep(Tc_1), ...,
          Rep(Tc_k)],Rep(A)}</c>.</p>
      </item>
      <item>
        <p>If E is a try expression
          <c>try B of Cc_1 ; ... ; Cc_k  catch Tc_1 ; ... ; Tc_n after A
          end</c>, where <c>B</c> and <c>A</c> are a bodies,
          each <c>Cc_i</c> is a case clause,
          and each <c>Tc_j</c> is a catch clause, then Rep(E) =
          <c>{'try',LINE,Rep(B),[Rep(Cc_1), ..., Rep(Cc_k)],[Rep(Tc_1), ...,
          Rep(Tc_n)],Rep(A)}</c>.</p>
      </item>
      <item>
        <p>If E is a variable <c>V</c>, then Rep(E) = <c>{var,LINE,A}</c>,
          where <c>A</c> is an atom with a printname consisting of the same
          characters as <c>V</c>.</p>
      </item>
    </list>

    <section>
      <title>Qualifiers</title>
      <p>A qualifier Q is one of the following:</p>

      <list type="bulleted">
        <item>
          <p>If Q is a filter <c>E</c>, where <c>E</c> is an expression, then
            Rep(Q) = <c>Rep(E)</c>.</p>
        </item>
        <item>
          <p>If Q is a generator <c>P &lt;- E</c>, where <c>P</c> is
            a pattern and <c>E</c> is an expression, then Rep(Q) =
            <c>{generate,LINE,Rep(P),Rep(E)}</c>.</p>
        </item>
        <item>
          <p>If Q is a bitstring generator <c>P &lt;= E</c>, where <c>P</c> is
            a pattern and <c>E</c> is an expression, then Rep(Q) =
            <c>{b_generate,LINE,Rep(P),Rep(E)}</c>.</p>
        </item>
      </list>
    </section>

    <section>
      <title>Bitstring Element Type Specifiers</title>
      <p>A type specifier list TSL for a bitstring element is a sequence
        of type specifiers <c>TS_1 - ... - TS_k</c>, and
        Rep(TSL) = <c>[Rep(TS_1), ..., Rep(TS_k)]</c>.</p>

      <list type="bulleted">
        <item>
          <p>If TS is a type specifier <c>A</c>, where <c>A</c> is an atom,
            then Rep(TS) = <c>A</c>.</p>
        </item>
        <item>
          <p>If TS is a type specifier <c>A:Value</c>,
            where <c>A</c> is an atom and <c>Value</c> is an integer,
            then Rep(TS) = <c>{A,Value}</c>.</p>
        </item>
      </list>
    </section>

    <section>
      <title>Associations</title>
      <p>An association A is one of the following:</p>

      <list type="bulleted">
         <item>
           <p>If A is an association <c>K => V</c>,
             then Rep(A) = <c>{map_field_assoc,LINE,Rep(K),Rep(V)}</c>.</p>
        </item>
        <item>
          <p>If A is an association <c>K := V</c>,
            then Rep(A) = <c>{map_field_exact,LINE,Rep(K),Rep(V)}</c>.</p>
        </item>
      </list>
    </section>
  </section>

  <section>
    <title>Clauses</title>
    <p>There are function clauses, if clauses, case clauses,
      and catch clauses.</p>

    <p>A clause C is one of the following:</p>

    <list type="bulleted">
      <item>
        <p>If C is a case clause <c>P -> B</c>,
          where <c>P</c> is a pattern and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,[Rep(P)],[],Rep(B)}</c>.</p>
      </item>
      <item>
        <p>If C is a case clause <c>P when Gs -> B</c>,
          where <c>P</c> is a pattern,
          <c>Gs</c> is a guard sequence, and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,[Rep(P)],Rep(Gs),Rep(B)}</c>.</p>
      </item>
      <item>
        <p>If C is a catch clause <c>P -> B</c>,
          where <c>P</c> is a pattern and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,[Rep({throw,P,_})],[],Rep(B)}</c>,
	  that is, a catch clause with an explicit exception class
	  <c>throw</c> and with or without an explicit stacktrace
	  variable <c>_</c> cannot be distinguished from a catch clause
	  without an explicit exception class and without an explicit
	  stacktrace variable.</p>
      </item>
      <item>
        <p>If C is a catch clause <c>X : P -> B</c>,
          where <c>X</c> is an atomic literal or a variable pattern,
          <c>P</c> is a pattern, and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,[Rep({X,P,_})],[],Rep(B)}</c>,
	  that is, a catch clause with an explicit exception class and
	  with an explicit stacktrace variable <c>_</c> cannot be
	  distinguished from a catch clause with an explicit exception
	  class and without an explicit stacktrace variable.</p>
      </item>
      <item>
        <p>If C is a catch clause <c>X : P : S -> B</c>,
          where <c>X</c> is an atomic literal or a variable pattern,
          <c>P</c> is a pattern, <c>S</c> is a variable, and <c>B</c>
	  is a body, then
          Rep(C) = <c>{clause,LINE,[Rep({X,P,S})],[],Rep(B)}</c>.</p>
      </item>
      <item>
        <p>If C is a catch clause <c>P when Gs -> B</c>,
          where <c>P</c> is a pattern, <c>Gs</c> is a guard sequence,
          and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,[Rep({throw,P,_})],Rep(Gs),Rep(B)}</c>,
	  that is, a catch clause with an explicit exception class
	  <c>throw</c> and with or without an explicit stacktrace
	  variable <c>_</c> cannot be distinguished from a catch clause
	  without an explicit exception class and without an explicit
	  stacktrace variable.</p>
      </item>
      <item>
        <p>If C is a catch clause <c>X : P when Gs -> B</c>,
          where <c>X</c> is an atomic literal or a variable pattern,
          <c>P</c> is a pattern, <c>Gs</c> is a guard sequence,
          and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,[Rep({X,P,_})],Rep(Gs),Rep(B)}</c>,
	  that is, a catch clause with an explicit exception class and
	  with an explicit stacktrace variable <c>_</c> cannot be
	  distinguished from a catch clause with an explicit exception
	  class and without an explicit stacktrace variable.</p>
      </item>
      <item>
        <p>If C is a catch clause <c>X : P : S when Gs -> B</c>,
          where <c>X</c> is an atomic literal or a variable pattern,
          <c>P</c> is a pattern, <c>Gs</c> is a guard sequence,
          <c>S</c> is a variable, and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,[Rep({X,P,S})],Rep(Gs),Rep(B)}</c>.</p>
      </item>
      <item>
        <p>If C is a function clause <c>( Ps ) -> B</c>,
          where <c>Ps</c> is a pattern sequence and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,Rep(Ps),[],Rep(B)}</c>.</p>
      </item>
      <item>
        <p>If C is a function clause <c>( Ps ) when Gs -> B</c>,
          where <c>Ps</c> is a pattern sequence,
          <c>Gs</c> is a guard sequence and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,Rep(Ps),Rep(Gs),Rep(B)}</c>.</p>
      </item>
      <item>
        <p>If C is an if clause <c>Gs -> B</c>,
          where <c>Gs</c> is a guard sequence and <c>B</c> is a body, then
          Rep(C) = <c>{clause,LINE,[],Rep(Gs),Rep(B)}</c>.</p>
      </item>
    </list>
  </section>

  <section>
    <title>Guards</title>
    <p>A guard sequence Gs is a sequence of guards <c>G_1; ...; G_k</c>, and
      Rep(Gs) = <c>[Rep(G_1), ..., Rep(G_k)]</c>. If the guard sequence is
      empty, then Rep(Gs) = <c>[]</c>.</p>

    <p>A guard G is a non-empty sequence of guard tests
      <c>Gt_1, ..., Gt_k</c>, and Rep(G) =
      <c>[Rep(Gt_1), ..., Rep(Gt_k)]</c>.</p>

    <p>A guard test Gt is one of the following:</p>

    <list type="bulleted">
      <item>
        <p>If Gt is an atomic literal <c>L</c>, then Rep(Gt) = Rep(L).</p>
      </item>
      <item>
        <p>If Gt is a bitstring constructor
          <c>&lt;&lt;Gt_1:Size_1/TSL_1, ..., Gt_k:Size_k/TSL_k>></c>,
          where each <c>Size_i</c> is a guard test and each
          <c>TSL_i</c> is a type specificer list, then Rep(Gt) =
          <c>{bin,LINE,[{bin_element,LINE,Rep(Gt_1),Rep(Size_1),Rep(TSL_1)},
          ..., {bin_element,LINE,Rep(Gt_k),Rep(Size_k),Rep(TSL_k)}]}</c>.
          For Rep(TSL), see above.
          An omitted <c>Size_i</c> is represented by <c>default</c>.
          An omitted <c>TSL_i</c> is represented by <c>default</c>.</p>
      </item>
      <item>
        <p>If Gt is a cons skeleton <c>[Gt_h | Gt_t]</c>, then Rep(Gt) =
          <c>{cons,LINE,Rep(Gt_h),Rep(Gt_t)}</c>.</p>
      </item>
      <item>
        <p>If Gt is a function call <c>A(Gt_1, ..., Gt_k)</c>,
          where <c>A</c> is an atom, then Rep(Gt) =
          <c>{call,LINE,Rep(A),[Rep(Gt_1), ..., Rep(Gt_k)]}</c>.</p>
      </item>
      <item>
        <p>If Gt is a function call <c>A_m:A(Gt_1, ..., Gt_k)</c>,
          where <c>A_m</c> is the atom <c>erlang</c> and <c>A</c> is
          an atom or an operator, then Rep(Gt) =
          <c>{call,LINE,{remote,LINE,Rep(A_m),Rep(A)},[Rep(Gt_1), ...,
          Rep(Gt_k)]}</c>.</p>
      </item>
      <item>
        <p>If Gt is a map creation <c>#{A_1, ..., A_k}</c>,
          where each <c>A_i</c> is an association <c>Gt_i_1 => Gt_i_2</c>,
	  then Rep(Gt) = <c>{map,LINE,[Rep(A_1), ..., Rep(A_k)]}</c>.
          For Rep(A), see above.</p>
      </item>
      <item>
        <p>If Gt is a map update <c>Gt_0#{A_1, ..., A_k}</c>,
          where each <c>A_i</c> is an association <c>Gt_i_1 => Gt_i_2</c>
          or <c>Gt_i_1 := Gt_i_2</c>, then Rep(Gt) =
          <c>{map,LINE,Rep(Gt_0),[Rep(A_1), ..., Rep(A_k)]}</c>.
          For Rep(A), see above.</p>
      </item>
      <item>
        <p>If Gt is nil, <c>[]</c>, then Rep(Gt) = <c>{nil,LINE}</c>.</p>
      </item>
      <item>
        <p>If Gt is an operator guard test <c>Gt_1 Op Gt_2</c>,
          where <c>Op</c> is a binary operator other than match
          operator <c>=</c>, then Rep(Gt) =
          <c>{op,LINE,Op,Rep(Gt_1),Rep(Gt_2)}</c>.</p>
      </item>
      <item>
        <p>If Gt is an operator guard test <c>Op Gt_0</c>,
          where <c>Op</c> is a unary operator, then Rep(Gt) =
          <c>{op,LINE,Op,Rep(Gt_0)}</c>.</p>
      </item>
      <item>
        <p>If Gt is a parenthesized guard test <c>( Gt_0 )</c>, then Rep(Gt) =
          <c>Rep(Gt_0)</c>, that is, parenthesized
          guard tests cannot be distinguished from their bodies.</p>
      </item>
      <item>
        <p>If Gt is a record creation
          <c>#Name{Field_1=Gt_1, ..., Field_k=Gt_k}</c>,
           where each <c>Field_i</c> is an atom or <c>_</c>, then Rep(Gt) =
           <c>{record,LINE,Name,[{record_field,LINE,Rep(Field_1),Rep(Gt_1)},
           ..., {record_field,LINE,Rep(Field_k),Rep(Gt_k)}]}</c>.</p>
      </item>
      <item>
        <p>If Gt is  a record field access <c>Gt_0#Name.Field</c>,
          where <c>Field</c> is an atom, then Rep(Gt) =
          <c>{record_field,LINE,Rep(Gt_0),Name,Rep(Field)}</c>.</p>
      </item>
      <item>
        <p>If Gt is a record field index <c>#Name.Field</c>,
          where <c>Field</c> is an atom, then Rep(Gt) =
          <c>{record_index,LINE,Name,Rep(Field)}</c>.</p>
      </item>
      <item>
        <p>If Gt is a tuple skeleton <c>{Gt_1, ..., Gt_k}</c>, then Rep(Gt) =
          <c>{tuple,LINE,[Rep(Gt_1), ..., Rep(Gt_k)]}</c>.</p>
      </item>
      <item>
        <p>If Gt is a variable pattern <c>V</c>, then Rep(Gt) =
          <c>{var,LINE,A}</c>, where A is an atom with
          a printname consisting of the same characters as <c>V</c>.</p>
      </item>
    </list>

    <p>Notice that every guard test has the same source form as some expression,
      and is represented in the same way as the corresponding expression.</p>
  </section>

  <section>
    <title>Types</title>
    <list type="bulleted">
      <item>
        <p>If T is an annotated type <c>A :: T_0</c>,
          where <c>A</c> is a variable, then Rep(T) =
          <c>{ann_type,LINE,[Rep(A),Rep(T_0)]}</c>.</p>
      </item>
      <item>
        <p>If T is an atom, a character, or an integer literal L,
	  then Rep(T) = Rep(L).</p>
      </item>
      <item>
        <p>If T is a bitstring type <c>&lt;&lt;_:M,_:_*N>></c>,
          where <c>M</c> and <c>N</c> are singleton integer types, then Rep(T) =
          <c>{type,LINE,binary,[Rep(M),Rep(N)]}</c>.</p>
      </item>
      <item>
        <p>If T is the empty list type <c>[]</c>, then Rep(T) =
          <c>{type,Line,nil,[]}</c>, that is, the empty list type
          <c>[]</c> cannot be distinguished from the predefined type
          <c>nil()</c>.</p>
      </item>
      <item>
        <p>If T is a fun type <c>fun()</c>, then Rep(T) =
          <c>{type,LINE,'fun',[]}</c>.</p>
      </item>
      <item>
        <p>If T is a fun type <c>fun((...) -> T_0)</c>, then Rep(T) =
          <c>{type,LINE,'fun',[{type,LINE,any},Rep(T_0)]}</c>.</p>
      </item>
      <item>
        <p>If T is a fun type <c>fun(Ft)</c>, where
          <c>Ft</c> is a function type, then Rep(T) = <c>Rep(Ft)</c>.
          For Rep(Ft), see below.</p>
      </item>
      <item>
        <p>If T is an integer range type <c>L .. H</c>,
          where <c>L</c> and <c>H</c> are singleton integer types, then Rep(T) =
          <c>{type,LINE,range,[Rep(L),Rep(H)]}</c>.</p>
      </item>
      <item>
        <p>If T is a map type <c>map()</c>, then Rep(T) =
          <c>{type,LINE,map,any}</c>.</p>
      </item>
      <item>
        <p>If T is a map type <c>#{A_1, ..., A_k}</c>, where each
          <c>A_i</c> is an association type, then Rep(T) =
          <c>{type,LINE,map,[Rep(A_1), ..., Rep(A_k)]}</c>.
          For Rep(A), see below.</p>
      </item>
      <item>
        <p>If T is an operator type <c>T_1 Op T_2</c>,
          where <c>Op</c> is a binary operator (this is an occurrence of
          an expression that can be evaluated to an integer at compile
          time), then Rep(T) =
          <c>{op,LINE,Op,Rep(T_1),Rep(T_2)}</c>.</p>
      </item>
      <item>
        <p>If T is an operator type <c>Op T_0</c>, where <c>Op</c> is a
          unary operator (this is an occurrence of an expression that can
          be evaluated to an integer at compile time), then Rep(T) =
          <c>{op,LINE,Op,Rep(T_0)}</c>.</p>
      </item>
      <item>
        <p>If T is <c>( T_0 )</c>, then Rep(T) = <c>Rep(T_0)</c>, that is,
          parenthesized types cannot be distinguished from their bodies.</p>
      </item>
      <item>
        <p>If T is a predefined (or built-in) type <c>N(T_1, ..., T_k)</c>,
          then Rep(T) = <c>{type,LINE,N,[Rep(T_1), ..., Rep(T_k)]}</c>.</p>
      </item>
      <item>
        <p>If T is a record type <c>#Name{F_1, ..., F_k}</c>,
          where each <c>F_i</c> is a record field type, then Rep(T) =
          <c>{type,LINE,record,[Rep(Name),Rep(F_1), ..., Rep(F_k)]}</c>.
          For Rep(F), see below.</p>
      </item>
      <item>
        <p>If T is a remote type <c>M:N(T_1, ..., T_k)</c>, then Rep(T) =
          <c>{remote_type,LINE,[Rep(M),Rep(N),[Rep(T_1), ...,
          Rep(T_k)]]}</c>.</p>
      </item>
      <item>
        <p>If T is a tuple type <c>tuple()</c>, then Rep(T) =
          <c>{type,LINE,tuple,any}</c>.</p>
      </item>
      <item>
        <p>If T is a tuple type <c>{T_1, ..., T_k}</c>, then Rep(T) =
          <c>{type,LINE,tuple,[Rep(T_1), ..., Rep(T_k)]}</c>.</p>
      </item>
      <item>
        <p>If T is a type union <c>T_1 | ... | T_k</c>, then Rep(T) =
          <c>{type,LINE,union,[Rep(T_1), ..., Rep(T_k)]}</c>.</p>
      </item>
      <item>
        <p>If T is a type variable <c>V</c>, then Rep(T) =
          <c>{var,LINE,A}</c>, where <c>A</c> is an atom with a printname
          consisting of the same characters as <c>V</c>. A type variable
          is any variable except underscore (<c>_</c>).</p>
      </item>
      <item>
        <p>If T is a user-defined type <c>N(T_1, ..., T_k)</c>, then Rep(T) =
          <c>{user_type,LINE,N,[Rep(T_1), ..., Rep(T_k)]}</c>.</p>
      </item>
    </list>

    <section>
      <title>Function Types</title>
      <p>A function type Ft is one of the following:</p>

      <list type="bulleted">
        <item>
          <p>If Ft is a constrained function type <c>Ft_1 when Fc</c>,
            where <c>Ft_1</c> is a function type and
            <c>Fc</c> is a function constraint, then Rep(T) =
            <c>{type,LINE,bounded_fun,[Rep(Ft_1),Rep(Fc)]}</c>.
            For Rep(Fc), see below.</p>
        </item>
        <item>
          <p>If Ft is a function type <c>(T_1, ..., T_n) -> T_0</c>,
            where each <c>T_i</c> is a type, then Rep(Ft) =
            <c>{type,LINE,'fun',[{type,LINE,product,[Rep(T_1), ...,
            Rep(T_n)]},Rep(T_0)]}</c>.</p>
        </item>
      </list>
    </section>

    <section>
      <title>Function Constraints</title>
      <p>A function constraint Fc is a non-empty sequence of constraints
        <c>C_1, ..., C_k</c>, and
        Rep(Fc) = <c>[Rep(C_1), ..., Rep(C_k)]</c>.</p>

      <list type="bulleted">
        <item>If C is a constraint <c>V :: T</c>,
          where <c>V</c> is a type variable
          and <c>T</c> is a type, then Rep(C) =
          <c>{type,LINE,constraint,[{atom,LINE,is_subtype},[Rep(V),Rep(T)]]}</c>.
        </item>
      </list>
    </section>

    <section>
      <title>Association Types</title>
      <list type="bulleted">
        <item>
          <p>If A is an association type <c>K => V</c>,
            where <c>K</c> and <c>V</c> are types, then Rep(A) =
            <c>{type,LINE,map_field_assoc,[Rep(K),Rep(V)]}</c>.</p>
        </item>
        <item>
          <p>If A is an association type <c>K := V</c>,
            where <c>K</c> and <c>V</c> are types, then Rep(A) =
            <c>{type,LINE,map_field_exact,[Rep(K),Rep(V)]}</c>.</p>
        </item>
      </list>
    </section>

    <section>
      <title>Record Field Types</title>
      <list type="bulleted">
        <item>If F is a record field type <c>Name :: Type</c>,
          where <c>Type</c> is a type, then Rep(F) =
          <c>{type,LINE,field_type,[Rep(Name),Rep(Type)]}</c>.
        </item>
      </list>
    </section>
  </section>

  <section>
    <title>The Abstract Format after Preprocessing</title>
    <p>The compilation option <c>debug_info</c> can be specified to the
      compiler to have the abstract code stored in
      the <c>abstract_code</c> chunk in the Beam file
      (for debugging purposes).</p>

    <p>As from Erlang/OTP R9C, the <c>abstract_code</c> chunk contains
      <c>{raw_abstract_v1,AbstractCode}</c>, where <c>AbstractCode</c> is the
      abstract code as described in this section.</p>

    <p>In OTP releases before R9C, the abstract code after some more
      processing was stored in the Beam file. The first element of the
      tuple would be either <c>abstract_v1</c> (in OTP R7B) or
      <c>abstract_v2</c> (in OTP R8B).</p>
  </section>
</chapter>