1Stdlib.Format(3) OCaml library Stdlib.Format(3)
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6 Stdlib.Format - no description
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9 Module Stdlib.Format
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12 Module Format
13 : (module Stdlib__Format)
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23 Introduction
24 You may consider this module as providing an extension to the printf
25 facility to provide automatic line splitting. The addition of
26 pretty-printing annotations to your regular printf format strings gives
27 you fancy indentation and line breaks. Pretty-printing annotations are
28 described below in the documentation of the function Format.fprintf .
29
30 You may also use the explicit pretty-printing box management and print‐
31 ing functions provided by this module. This style is more basic but
32 more verbose than the concise fprintf format strings.
33
34 For instance, the sequence open_box 0; print_string "x ="; print_space
35 ();
36 print_int 1; close_box (); print_newline () that prints x = 1
37 within a pretty-printing box, can be abbreviated as printf "@[%s@
38 %i@]@." "x =" 1 , or even shorter printf "@[x =@ %i@]@." 1 .
39
40 Rule of thumb for casual users of this library:
41
42 -use simple pretty-printing boxes (as obtained by open_box 0 );
43
44 -use simple break hints as obtained by print_cut () that outputs a sim‐
45 ple break hint, or by print_space () that outputs a space indicating a
46 break hint;
47
48 -once a pretty-printing box is open, display its material with basic
49 printing functions (e. g. print_int and print_string );
50
51 -when the material for a pretty-printing box has been printed, call
52 close_box () to close the box;
53
54 -at the end of pretty-printing, flush the pretty-printer to display all
55 the remaining material, e.g. evaluate print_newline () .
56
57 The behavior of pretty-printing commands is unspecified if there is no
58 open pretty-printing box. Each box opened by one of the open_ functions
59 below must be closed using close_box for proper formatting. Otherwise,
60 some of the material printed in the boxes may not be output, or may be
61 formatted incorrectly.
62
63 In case of interactive use, each phrase is executed in the initial
64 state of the standard pretty-printer: after each phrase execution, the
65 interactive system closes all open pretty-printing boxes, flushes all
66 pending text, and resets the standard pretty-printer.
67
68 Warning: mixing calls to pretty-printing functions of this module with
69 calls to Stdlib low level output functions is error prone.
70
71 The pretty-printing functions output material that is delayed in the
72 pretty-printer queue and stacks in order to compute proper line split‐
73 ting. In contrast, basic I/O output functions write directly in their
74 output device. As a consequence, the output of a basic I/O function may
75 appear before the output of a pretty-printing function that has been
76 called before. For instance,
77 Stdlib.print_string "<";
78 Format.print_string "PRETTY";
79 Stdlib.print_string ">";
80 Format.print_string "TEXT";
81 leads to output <>PRETTYTEXT .
82
83 Formatters
84 type formatter
85
86
87 Abstract data corresponding to a pretty-printer (also called a format‐
88 ter) and all its machinery. See also Format.formatter .
89
90
91
92
93 Pretty-printing boxes
94 The pretty-printing engine uses the concepts of pretty-printing box and
95 break hint to drive indentation and line splitting behavior of the
96 pretty-printer.
97
98 Each different pretty-printing box kind introduces a specific line
99 splitting policy:
100
101
102 -within an horizontal box, break hints never split the line (but the
103 line may be split in a box nested deeper),
104
105 -within a vertical box, break hints always split the line,
106
107 -within an horizontal/vertical box, if the box fits on the current line
108 then break hints never split the line, otherwise break hint always
109 split the line,
110
111 -within a compacting box, a break hint never splits the line, unless
112 there is no more room on the current line.
113
114 Note that line splitting policy is box specific: the policy of a box
115 does not rule the policy of inner boxes. For instance, if a vertical
116 box is nested in an horizontal box, all break hints within the vertical
117 box will split the line.
118
119 Moreover, opening a box after the Format.maxindent splits the line
120 whether or not the box would end up fitting on the line.
121
122 val pp_open_box : formatter -> int -> unit
123
124
125
126
127 val open_box : int -> unit
128
129
130 pp_open_box ppf d opens a new compacting pretty-printing box with off‐
131 set d in the formatter ppf .
132
133 Within this box, the pretty-printer prints as much as possible material
134 on every line.
135
136 A break hint splits the line if there is no more room on the line to
137 print the remainder of the box.
138
139 Within this box, the pretty-printer emphasizes the box structure: if a
140 structural box does not fit fully on a simple line, a break hint also
141 splits the line if the splitting ``moves to the left'' (i.e. the new
142 line gets an indentation smaller than the one of the current line).
143
144 This box is the general purpose pretty-printing box.
145
146 If the pretty-printer splits the line in the box, offset d is added to
147 the current indentation.
148
149
150
151 val pp_close_box : formatter -> unit -> unit
152
153
154
155
156 val close_box : unit -> unit
157
158 Closes the most recently open pretty-printing box.
159
160
161
162 val pp_open_hbox : formatter -> unit -> unit
163
164
165
166
167 val open_hbox : unit -> unit
168
169
170 pp_open_hbox ppf () opens a new 'horizontal' pretty-printing box.
171
172 This box prints material on a single line.
173
174 Break hints in a horizontal box never split the line. (Line splitting
175 may still occur inside boxes nested deeper).
176
177
178
179 val pp_open_vbox : formatter -> int -> unit
180
181
182
183
184 val open_vbox : int -> unit
185
186
187 pp_open_vbox ppf d opens a new 'vertical' pretty-printing box with off‐
188 set d .
189
190 This box prints material on as many lines as break hints in the box.
191
192 Every break hint in a vertical box splits the line.
193
194 If the pretty-printer splits the line in the box, d is added to the
195 current indentation.
196
197
198
199 val pp_open_hvbox : formatter -> int -> unit
200
201
202
203
204 val open_hvbox : int -> unit
205
206
207 pp_open_hvbox ppf d opens a new 'horizontal/vertical' pretty-printing
208 box with offset d .
209
210 This box behaves as an horizontal box if it fits on a single line, oth‐
211 erwise it behaves as a vertical box.
212
213 If the pretty-printer splits the line in the box, d is added to the
214 current indentation.
215
216
217
218 val pp_open_hovbox : formatter -> int -> unit
219
220
221
222
223 val open_hovbox : int -> unit
224
225
226 pp_open_hovbox ppf d opens a new 'horizontal-or-vertical' pretty-print‐
227 ing box with offset d .
228
229 This box prints material as much as possible on every line.
230
231 A break hint splits the line if there is no more room on the line to
232 print the remainder of the box.
233
234 If the pretty-printer splits the line in the box, d is added to the
235 current indentation.
236
237
238
239
240 Formatting functions
241 val pp_print_string : formatter -> string -> unit
242
243
244
245
246 val print_string : string -> unit
247
248
249 pp_print_string ppf s prints s in the current pretty-printing box.
250
251
252
253 val pp_print_bytes : formatter -> bytes -> unit
254
255
256
257
258 val print_bytes : bytes -> unit
259
260
261 pp_print_bytes ppf b prints b in the current pretty-printing box.
262
263
264 Since 4.13.0
265
266
267
268 val pp_print_as : formatter -> int -> string -> unit
269
270
271
272
273 val print_as : int -> string -> unit
274
275
276 pp_print_as ppf len s prints s in the current pretty-printing box. The
277 pretty-printer formats s as if it were of length len .
278
279
280
281 val pp_print_int : formatter -> int -> unit
282
283
284
285
286 val print_int : int -> unit
287
288 Print an integer in the current pretty-printing box.
289
290
291
292 val pp_print_float : formatter -> float -> unit
293
294
295
296
297 val print_float : float -> unit
298
299 Print a floating point number in the current pretty-printing box.
300
301
302
303 val pp_print_char : formatter -> char -> unit
304
305
306
307
308 val print_char : char -> unit
309
310 Print a character in the current pretty-printing box.
311
312
313
314 val pp_print_bool : formatter -> bool -> unit
315
316
317
318
319 val print_bool : bool -> unit
320
321 Print a boolean in the current pretty-printing box.
322
323
324
325
326 Break hints
327 A 'break hint' tells the pretty-printer to output some space or split
328 the line whichever way is more appropriate to the current pretty-print‐
329 ing box splitting rules.
330
331 Break hints are used to separate printing items and are mandatory to
332 let the pretty-printer correctly split lines and indent items.
333
334 Simple break hints are:
335
336 -the 'space': output a space or split the line if appropriate,
337
338 -the 'cut': split the line if appropriate.
339
340 Note: the notions of space and line splitting are abstract for the
341 pretty-printing engine, since those notions can be completely redefined
342 by the programmer. However, in the pretty-printer default setting,
343 ``output a space'' simply means printing a space character (ASCII code
344 32) and ``split the line'' means printing a newline character (ASCII
345 code 10).
346
347 val pp_print_space : formatter -> unit -> unit
348
349
350
351
352 val print_space : unit -> unit
353
354
355 pp_print_space ppf () emits a 'space' break hint: the pretty-printer
356 may split the line at this point, otherwise it prints one space.
357
358
359 pp_print_space ppf () is equivalent to pp_print_break ppf 1 0 .
360
361
362
363 val pp_print_cut : formatter -> unit -> unit
364
365
366
367
368 val print_cut : unit -> unit
369
370
371 pp_print_cut ppf () emits a 'cut' break hint: the pretty-printer may
372 split the line at this point, otherwise it prints nothing.
373
374
375 pp_print_cut ppf () is equivalent to pp_print_break ppf 0 0 .
376
377
378
379 val pp_print_break : formatter -> int -> int -> unit
380
381
382
383
384 val print_break : int -> int -> unit
385
386
387 pp_print_break ppf nspaces offset emits a 'full' break hint: the
388 pretty-printer may split the line at this point, otherwise it prints
389 nspaces spaces.
390
391 If the pretty-printer splits the line, offset is added to the current
392 indentation.
393
394
395
396 val pp_print_custom_break : formatter -> fits:string * int * string ->
397 breaks:string * int * string -> unit
398
399
400 pp_print_custom_break ppf ~fits:(s1, n, s2) ~breaks:(s3, m, s4) emits a
401 custom break hint: the pretty-printer may split the line at this point.
402
403 If it does not split the line, then the s1 is emitted, then n spaces,
404 then s2 .
405
406 If it splits the line, then it emits the s3 string, then an indent (ac‐
407 cording to the box rules), then an offset of m spaces, then the s4
408 string.
409
410 While n and m are handled by formatter_out_functions.out_indent , the
411 strings will be handled by formatter_out_functions.out_string . This
412 allows for a custom formatter that handles indentation distinctly, for
413 example, outputs <br/> tags or entities.
414
415 The custom break is useful if you want to change which visible
416 (non-whitespace) characters are printed in case of break or no break.
417 For example, when printing a list [a; b; c] , you might want to add a
418 trailing semicolon when it is printed vertically:
419
420
421 [
422 a;
423 b;
424 c;
425 ]
426
427
428 You can do this as follows:
429 printf "@[<v 0>[@;<0 2>@[<v 0>a;@,b;@,c@]%t]@]@\n"
430 (pp_print_custom_break ~fits:("", 0, "") ~breaks:(";", 0, ""))
431
432
433
434 Since 4.08.0
435
436
437
438 val pp_force_newline : formatter -> unit -> unit
439
440
441
442
443 val force_newline : unit -> unit
444
445 Force a new line in the current pretty-printing box.
446
447 The pretty-printer must split the line at this point,
448
449 Not the normal way of pretty-printing, since imperative line splitting
450 may interfere with current line counters and box size calculation. Us‐
451 ing break hints within an enclosing vertical box is a better alterna‐
452 tive.
453
454
455
456 val pp_print_if_newline : formatter -> unit -> unit
457
458
459
460
461 val print_if_newline : unit -> unit
462
463 Execute the next formatting command if the preceding line has just been
464 split. Otherwise, ignore the next formatting command.
465
466
467
468
469 Pretty-printing termination
470 val pp_print_flush : formatter -> unit -> unit
471
472
473
474
475 val print_flush : unit -> unit
476
477 End of pretty-printing: resets the pretty-printer to initial state.
478
479 All open pretty-printing boxes are closed, all pending text is printed.
480 In addition, the pretty-printer low level output device is flushed to
481 ensure that all pending text is really displayed.
482
483 Note: never use print_flush in the normal course of a pretty-printing
484 routine, since the pretty-printer uses a complex buffering machinery to
485 properly indent the output; manually flushing those buffers at random
486 would conflict with the pretty-printer strategy and result to poor ren‐
487 dering.
488
489 Only consider using print_flush when displaying all pending material is
490 mandatory (for instance in case of interactive use when you want the
491 user to read some text) and when resetting the pretty-printer state
492 will not disturb further pretty-printing.
493
494 Warning: If the output device of the pretty-printer is an output chan‐
495 nel, repeated calls to print_flush means repeated calls to flush to
496 flush the out channel; these explicit flush calls could foil the
497 buffering strategy of output channels and could dramatically impact ef‐
498 ficiency.
499
500
501
502 val pp_print_newline : formatter -> unit -> unit
503
504
505
506
507 val print_newline : unit -> unit
508
509 End of pretty-printing: resets the pretty-printer to initial state.
510
511 All open pretty-printing boxes are closed, all pending text is printed.
512
513 Equivalent to Format.print_flush followed by a new line. See corre‐
514 sponding words of caution for Format.print_flush .
515
516 Note: this is not the normal way to output a new line; the preferred
517 method is using break hints within a vertical pretty-printing box.
518
519
520
521
522 Margin
523 val pp_set_margin : formatter -> int -> unit
524
525
526
527
528 val set_margin : int -> unit
529
530
531 pp_set_margin ppf d sets the right margin to d (in characters): the
532 pretty-printer splits lines that overflow the right margin according to
533 the break hints given. Setting the margin to d means that the format‐
534 ting engine aims at printing at most d-1 characters per line. Nothing
535 happens if d is smaller than 2. If d is too large, the right margin is
536 set to the maximum admissible value (which is greater than 10 ^ 9 ).
537 If d is less than the current maximum indentation limit, the maximum
538 indentation limit is decreased while trying to preserve a minimal ratio
539 max_indent/margin>=50% and if possible the current difference margin -
540 max_indent .
541
542 See also Format.pp_set_geometry .
543
544
545
546 val pp_get_margin : formatter -> unit -> int
547
548
549
550
551 val get_margin : unit -> int
552
553 Returns the position of the right margin.
554
555
556
557
558 Maximum indentation limit
559 val pp_set_max_indent : formatter -> int -> unit
560
561
562
563
564 val set_max_indent : int -> unit
565
566
567 pp_set_max_indent ppf d sets the maximum indentation limit of lines to
568 d (in characters): once this limit is reached, new pretty-printing
569 boxes are rejected to the left, unless the enclosing box fully fits on
570 the current line. As an illustration,
571 set_margin 10; set_max_indent 5; printf "@[123456@[7@]89A@]@."
572 yields
573 123456
574 789A
575
576 because the nested box "@[7@]" is opened after the maximum indentation
577 limit ( 7>5 ) and its parent box does not fit on the current line. Ei‐
578 ther decreasing the length of the parent box to make it fit on a line:
579 printf "@[123456@[7@]89@]@."
580 or opening an intermediary box before the maximum indentation limit
581 which fits on the current line
582 printf "@[123@[456@[7@]89@]A@]@."
583 avoids the rejection to the left of the inner boxes and print respec‐
584 tively "123456789" and "123456789A" . Note also that vertical boxes
585 never fit on a line whereas horizontal boxes always fully fit on the
586 current line. Opening a box may split a line whereas the contents may
587 have fit. If this behavior is problematic, it can be curtailed by set‐
588 ting the maximum indentation limit to margin - 1 . Note that setting
589 the maximum indentation limit to margin is invalid.
590
591 Nothing happens if d is smaller than 2.
592
593 If d is too large, the limit is set to the maximum admissible value
594 (which is greater than 10 ^ 9 ).
595
596 If d is greater or equal than the current margin, it is ignored, and
597 the current maximum indentation limit is kept.
598
599 See also Format.pp_set_geometry .
600
601
602
603 val pp_get_max_indent : formatter -> unit -> int
604
605
606
607
608 val get_max_indent : unit -> int
609
610 Return the maximum indentation limit (in characters).
611
612
613
614
615 Geometry
616 Geometric functions can be used to manipulate simultaneously the cou‐
617 pled variables, margin and maxixum indentation limit.
618
619 type geometry = {
620 max_indent : int ;
621 margin : int ;
622 }
623
624
625
626
627
628 val check_geometry : geometry -> bool
629
630 Check if the formatter geometry is valid: 1 < max_indent < margin
631
632
633
634
635 val pp_set_geometry : formatter -> max_indent:int -> margin:int -> unit
636
637
638
639
640 val set_geometry : max_indent:int -> margin:int -> unit
641
642
643
644
645 val pp_safe_set_geometry : formatter -> max_indent:int -> margin:int ->
646 unit
647
648
649
650
651 val safe_set_geometry : max_indent:int -> margin:int -> unit
652
653
654 pp_set_geometry ppf ~max_indent ~margin sets both the margin and maxi‐
655 mum indentation limit for ppf .
656
657 When 1 < max_indent < margin , pp_set_geometry ppf ~max_indent ~margin
658 is equivalent to pp_set_margin ppf margin; pp_set_max_indent ppf
659 max_indent ; and avoids the subtly incorrect pp_set_max_indent ppf
660 max_indent; pp_set_margin ppf margin ;
661
662 Outside of this domain, pp_set_geometry raises an invalid argument ex‐
663 ception whereas pp_safe_set_geometry does nothing.
664
665
666 Since 4.08.0
667
668
669
670 val pp_update_geometry : formatter -> (geometry -> geometry) -> unit
671
672
673 pp_update_geometry ppf (fun geo -> { geo with ... }) lets you update a
674 formatter's geometry in a way that is robust to extension of the geome‐
675 try record with new fields.
676
677 Raises an invalid argument exception if the returned geometry does not
678 satisfy Format.check_geometry .
679
680
681 Since 4.11.0
682
683
684
685 val update_geometry : (geometry -> geometry) -> unit
686
687
688
689
690 val pp_get_geometry : formatter -> unit -> geometry
691
692
693
694
695 val get_geometry : unit -> geometry
696
697 Return the current geometry of the formatter
698
699
700 Since 4.08.0
701
702
703
704
705 Maximum formatting depth
706 The maximum formatting depth is the maximum number of pretty-printing
707 boxes simultaneously open.
708
709 Material inside boxes nested deeper is printed as an ellipsis (more
710 precisely as the text returned by Format.get_ellipsis_text () ).
711
712 val pp_set_max_boxes : formatter -> int -> unit
713
714
715
716
717 val set_max_boxes : int -> unit
718
719
720 pp_set_max_boxes ppf max sets the maximum number of pretty-printing
721 boxes simultaneously open.
722
723 Material inside boxes nested deeper is printed as an ellipsis (more
724 precisely as the text returned by Format.get_ellipsis_text () ).
725
726 Nothing happens if max is smaller than 2.
727
728
729
730 val pp_get_max_boxes : formatter -> unit -> int
731
732
733
734
735 val get_max_boxes : unit -> int
736
737 Returns the maximum number of pretty-printing boxes allowed before el‐
738 lipsis.
739
740
741
742 val pp_over_max_boxes : formatter -> unit -> bool
743
744
745
746
747 val over_max_boxes : unit -> bool
748
749 Tests if the maximum number of pretty-printing boxes allowed have al‐
750 ready been opened.
751
752
753
754
755 Tabulation boxes
756 A tabulation box prints material on lines divided into cells of fixed
757 length. A tabulation box provides a simple way to display vertical col‐
758 umns of left adjusted text.
759
760 This box features command set_tab to define cell boundaries, and com‐
761 mand print_tab to move from cell to cell and split the line when there
762 is no more cells to print on the line.
763
764 Note: printing within tabulation box is line directed, so arbitrary
765 line splitting inside a tabulation box leads to poor rendering. Yet,
766 controlled use of tabulation boxes allows simple printing of columns
767 within module Format .
768
769 val pp_open_tbox : formatter -> unit -> unit
770
771
772
773
774 val open_tbox : unit -> unit
775
776
777 open_tbox () opens a new tabulation box.
778
779 This box prints lines separated into cells of fixed width.
780
781 Inside a tabulation box, special tabulation markers defines points of
782 interest on the line (for instance to delimit cell boundaries). Func‐
783 tion Format.set_tab sets a tabulation marker at insertion point.
784
785 A tabulation box features specific tabulation breaks to move to next
786 tabulation marker or split the line. Function Format.print_tbreak
787 prints a tabulation break.
788
789
790
791 val pp_close_tbox : formatter -> unit -> unit
792
793
794
795
796 val close_tbox : unit -> unit
797
798 Closes the most recently opened tabulation box.
799
800
801
802 val pp_set_tab : formatter -> unit -> unit
803
804
805
806
807 val set_tab : unit -> unit
808
809 Sets a tabulation marker at current insertion point.
810
811
812
813 val pp_print_tab : formatter -> unit -> unit
814
815
816
817
818 val print_tab : unit -> unit
819
820
821 print_tab () emits a 'next' tabulation break hint: if not already set
822 on a tabulation marker, the insertion point moves to the first tabula‐
823 tion marker on the right, or the pretty-printer splits the line and in‐
824 sertion point moves to the leftmost tabulation marker.
825
826 It is equivalent to print_tbreak 0 0 .
827
828
829
830 val pp_print_tbreak : formatter -> int -> int -> unit
831
832
833
834
835 val print_tbreak : int -> int -> unit
836
837
838 print_tbreak nspaces offset emits a 'full' tabulation break hint.
839
840 If not already set on a tabulation marker, the insertion point moves to
841 the first tabulation marker on the right and the pretty-printer prints
842 nspaces spaces.
843
844 If there is no next tabulation marker on the right, the pretty-printer
845 splits the line at this point, then insertion point moves to the left‐
846 most tabulation marker of the box.
847
848 If the pretty-printer splits the line, offset is added to the current
849 indentation.
850
851
852
853
854 Ellipsis
855 val pp_set_ellipsis_text : formatter -> string -> unit
856
857
858
859
860 val set_ellipsis_text : string -> unit
861
862 Set the text of the ellipsis printed when too many pretty-printing
863 boxes are open (a single dot, . , by default).
864
865
866
867 val pp_get_ellipsis_text : formatter -> unit -> string
868
869
870
871
872 val get_ellipsis_text : unit -> string
873
874 Return the text of the ellipsis.
875
876
877
878
879 Semantic tags
880 type stag = ..
881
882
883 Semantic tags (or simply tags) are user's defined annotations to asso‐
884 ciate user's specific operations to printed entities.
885
886 Common usage of semantic tags is text decoration to get specific font
887 or text size rendering for a display device, or marking delimitation of
888 entities (e.g. HTML or TeX elements or terminal escape sequences).
889 More sophisticated usage of semantic tags could handle dynamic modifi‐
890 cation of the pretty-printer behavior to properly print the material
891 within some specific tags. For instance, we can define an RGB tag like
892 so:
893 type stag += RGB of {r:int;g:int;b:int}
894
895
896 In order to properly delimit printed entities, a semantic tag must be
897 opened before and closed after the entity. Semantic tags must be prop‐
898 erly nested like parentheses using Format.pp_open_stag and For‐
899 mat.pp_close_stag .
900
901 Tag specific operations occur any time a tag is opened or closed, At
902 each occurrence, two kinds of operations are performed tag-marking and
903 tag-printing:
904
905 -The tag-marking operation is the simpler tag specific operation: it
906 simply writes a tag specific string into the output device of the for‐
907 matter. Tag-marking does not interfere with line-splitting computation.
908
909 -The tag-printing operation is the more involved tag specific opera‐
910 tion: it can print arbitrary material to the formatter. Tag-printing is
911 tightly linked to the current pretty-printer operations.
912
913 Roughly speaking, tag-marking is commonly used to get a better render‐
914 ing of texts in the rendering device, while tag-printing allows fine
915 tuning of printing routines to print the same entity differently ac‐
916 cording to the semantic tags (i.e. print additional material or even
917 omit parts of the output).
918
919 More precisely: when a semantic tag is opened or closed then both and
920 successive 'tag-printing' and 'tag-marking' operations occur:
921
922 -Tag-printing a semantic tag means calling the formatter specific func‐
923 tion print_open_stag (resp. print_close_stag ) with the name of the
924 tag as argument: that tag-printing function can then print any regular
925 material to the formatter (so that this material is enqueued as usual
926 in the formatter queue for further line splitting computation).
927
928 -Tag-marking a semantic tag means calling the formatter specific func‐
929 tion mark_open_stag (resp. mark_close_stag ) with the name of the tag
930 as argument: that tag-marking function can then return the 'tag-opening
931 marker' (resp. `tag-closing marker') for direct output into the output
932 device of the formatter.
933
934 Being written directly into the output device of the formatter, seman‐
935 tic tag marker strings are not considered as part of the printing mate‐
936 rial that drives line splitting (in other words, the length of the
937 strings corresponding to tag markers is considered as zero for line
938 splitting).
939
940 Thus, semantic tag handling is in some sense transparent to
941 pretty-printing and does not interfere with usual indentation. Hence, a
942 single pretty-printing routine can output both simple 'verbatim' mate‐
943 rial or richer decorated output depending on the treatment of tags. By
944 default, tags are not active, hence the output is not decorated with
945 tag information. Once set_tags is set to true , the pretty-printer en‐
946 gine honors tags and decorates the output accordingly.
947
948 Default tag-marking functions behave the HTML way: Format.tag are en‐
949 closed in "<" and ">" while other tags are ignored; hence, opening
950 marker for tag string "t" is "<t>" and closing marker is "</t>" .
951
952 Default tag-printing functions just do nothing.
953
954 Tag-marking and tag-printing functions are user definable and can be
955 set by calling Format.set_formatter_stag_functions .
956
957 Semantic tag operations may be set on or off with Format.set_tags .
958 Tag-marking operations may be set on or off with Format.set_mark_tags .
959 Tag-printing operations may be set on or off with Format.set_print_tags
960 .
961
962
963 Since 4.08.0
964
965
966 type tag = string
967
968
969
970
971 type Format.stag +=
972 | String_tag of tag (* String_tag s is a string tag s . String tags
973 can be inserted either by explicitly using the constructor String_tag
974 or by using the dedicated format syntax "@{<s> ... @}" .
975
976
977 Since 4.08.0
978 *)
979
980
981
982
983
984 val pp_open_stag : formatter -> stag -> unit
985
986
987
988
989 val open_stag : stag -> unit
990
991
992 pp_open_stag ppf t opens the semantic tag named t .
993
994 The print_open_stag tag-printing function of the formatter is called
995 with t as argument; then the opening tag marker for t , as given by
996 mark_open_stag t , is written into the output device of the formatter.
997
998
999 Since 4.08.0
1000
1001
1002
1003 val pp_close_stag : formatter -> unit -> unit
1004
1005
1006
1007
1008 val close_stag : unit -> unit
1009
1010
1011 pp_close_stag ppf () closes the most recently opened semantic tag t .
1012
1013 The closing tag marker, as given by mark_close_stag t , is written into
1014 the output device of the formatter; then the print_close_stag
1015 tag-printing function of the formatter is called with t as argument.
1016
1017
1018 Since 4.08.0
1019
1020
1021
1022 val pp_set_tags : formatter -> bool -> unit
1023
1024
1025
1026
1027 val set_tags : bool -> unit
1028
1029
1030 pp_set_tags ppf b turns on or off the treatment of semantic tags (de‐
1031 fault is off).
1032
1033
1034
1035 val pp_set_print_tags : formatter -> bool -> unit
1036
1037
1038
1039
1040 val set_print_tags : bool -> unit
1041
1042
1043 pp_set_print_tags ppf b turns on or off the tag-printing operations.
1044
1045
1046
1047 val pp_set_mark_tags : formatter -> bool -> unit
1048
1049
1050
1051
1052 val set_mark_tags : bool -> unit
1053
1054
1055 pp_set_mark_tags ppf b turns on or off the tag-marking operations.
1056
1057
1058
1059 val pp_get_print_tags : formatter -> unit -> bool
1060
1061
1062
1063
1064 val get_print_tags : unit -> bool
1065
1066 Return the current status of tag-printing operations.
1067
1068
1069
1070 val pp_get_mark_tags : formatter -> unit -> bool
1071
1072
1073
1074
1075 val get_mark_tags : unit -> bool
1076
1077 Return the current status of tag-marking operations.
1078
1079
1080
1081 val pp_set_formatter_out_channel : formatter -> out_channel -> unit
1082
1083
1084 Redirecting the standard formatter output
1085 val set_formatter_out_channel : out_channel -> unit
1086
1087 Redirect the standard pretty-printer output to the given channel. (All
1088 the output functions of the standard formatter are set to the default
1089 output functions printing to the given channel.)
1090
1091
1092 set_formatter_out_channel is equivalent to Format.pp_set_format‐
1093 ter_out_channel std_formatter .
1094
1095
1096
1097 val pp_set_formatter_output_functions : formatter -> (string -> int ->
1098 int -> unit) -> (unit -> unit) -> unit
1099
1100
1101
1102
1103 val set_formatter_output_functions : (string -> int -> int -> unit) ->
1104 (unit -> unit) -> unit
1105
1106
1107 pp_set_formatter_output_functions ppf out flush redirects the standard
1108 pretty-printer output functions to the functions out and flush .
1109
1110 The out function performs all the pretty-printer string output. It is
1111 called with a string s , a start position p , and a number of charac‐
1112 ters n ; it is supposed to output characters p to p + n - 1 of s .
1113
1114 The flush function is called whenever the pretty-printer is flushed
1115 (via conversion %! , or pretty-printing indications @? or @. , or
1116 using low level functions print_flush or print_newline ).
1117
1118
1119
1120 val pp_get_formatter_output_functions : formatter -> unit -> (string ->
1121 int -> int -> unit) * (unit -> unit)
1122
1123
1124
1125
1126 val get_formatter_output_functions : unit -> (string -> int -> int ->
1127 unit) * (unit -> unit)
1128
1129 Return the current output functions of the standard pretty-printer.
1130
1131
1132
1133
1134 Redefining formatter output
1135 The Format module is versatile enough to let you completely redefine
1136 the meaning of pretty-printing output: you may provide your own func‐
1137 tions to define how to handle indentation, line splitting, and even
1138 printing of all the characters that have to be printed!
1139
1140 Redefining output functions
1141 type formatter_out_functions = {
1142 out_string : string -> int -> int -> unit ;
1143 out_flush : unit -> unit ;
1144 out_newline : unit -> unit ;
1145 out_spaces : int -> unit ;
1146 out_indent : int -> unit ; (* .B "Since" 4.06.0
1147 *)
1148 }
1149
1150
1151 The set of output functions specific to a formatter:
1152
1153 -the out_string function performs all the pretty-printer string output.
1154 It is called with a string s , a start position p , and a number of
1155 characters n ; it is supposed to output characters p to p + n - 1 of s
1156 .
1157
1158 -the out_flush function flushes the pretty-printer output device.
1159
1160 - out_newline is called to open a new line when the pretty-printer
1161 splits the line.
1162
1163 -the out_spaces function outputs spaces when a break hint leads to spa‐
1164 ces instead of a line split. It is called with the number of spaces to
1165 output.
1166
1167 -the out_indent function performs new line indentation when the
1168 pretty-printer splits the line. It is called with the indentation value
1169 of the new line.
1170
1171 By default:
1172
1173 -fields out_string and out_flush are output device specific; (e.g.
1174 output_string and flush for a out_channel device, or Buffer.add_sub‐
1175 string and ignore for a Buffer.t output device),
1176
1177 -field out_newline is equivalent to out_string "\n" 0 1 ;
1178
1179 -fields out_spaces and out_indent are equivalent to out_string
1180 (String.make n ' ') 0 n .
1181
1182
1183
1184 Since 4.01.0
1185
1186
1187
1188 val pp_set_formatter_out_functions : formatter -> formatter_out_func‐
1189 tions -> unit
1190
1191
1192
1193
1194 val set_formatter_out_functions : formatter_out_functions -> unit
1195
1196
1197 pp_set_formatter_out_functions ppf out_funs Set all the pretty-printer
1198 output functions of ppf to those of argument out_funs ,
1199
1200 This way, you can change the meaning of indentation (which can be some‐
1201 thing else than just printing space characters) and the meaning of new
1202 lines opening (which can be connected to any other action needed by the
1203 application at hand).
1204
1205 Reasonable defaults for functions out_spaces and out_newline are re‐
1206 spectively out_funs.out_string (String.make n ' ') 0 n and
1207 out_funs.out_string "\n" 0 1 .
1208
1209
1210 Since 4.01.0
1211
1212
1213
1214 val pp_get_formatter_out_functions : formatter -> unit -> format‐
1215 ter_out_functions
1216
1217
1218
1219
1220 val get_formatter_out_functions : unit -> formatter_out_functions
1221
1222 Return the current output functions of the pretty-printer, including
1223 line splitting and indentation functions. Useful to record the current
1224 setting and restore it afterwards.
1225
1226
1227 Since 4.01.0
1228
1229
1230
1231
1232 Redefining semantic tag operations
1233 type formatter_stag_functions = {
1234 mark_open_stag : stag -> string ;
1235 mark_close_stag : stag -> string ;
1236 print_open_stag : stag -> unit ;
1237 print_close_stag : stag -> unit ;
1238 }
1239
1240
1241 The semantic tag handling functions specific to a formatter: mark ver‐
1242 sions are the 'tag-marking' functions that associate a string marker to
1243 a tag in order for the pretty-printing engine to write those markers as
1244 0 length tokens in the output device of the formatter. print versions
1245 are the 'tag-printing' functions that can perform regular printing when
1246 a tag is closed or opened.
1247
1248
1249 Since 4.08.0
1250
1251
1252
1253 val pp_set_formatter_stag_functions : formatter -> formatter_stag_func‐
1254 tions -> unit
1255
1256
1257
1258
1259 val set_formatter_stag_functions : formatter_stag_functions -> unit
1260
1261
1262 pp_set_formatter_stag_functions ppf tag_funs changes the meaning of
1263 opening and closing semantic tag operations to use the functions in
1264 tag_funs when printing on ppf .
1265
1266 When opening a semantic tag with name t , the string t is passed to the
1267 opening tag-marking function (the mark_open_stag field of the record
1268 tag_funs ), that must return the opening tag marker for that name. When
1269 the next call to close_stag () happens, the semantic tag name t is sent
1270 back to the closing tag-marking function (the mark_close_stag field of
1271 record tag_funs ), that must return a closing tag marker for that name.
1272
1273 The print_ field of the record contains the tag-printing functions that
1274 are called at tag opening and tag closing time, to output regular mate‐
1275 rial in the pretty-printer queue.
1276
1277
1278 Since 4.08.0
1279
1280
1281
1282 val pp_get_formatter_stag_functions : formatter -> unit -> format‐
1283 ter_stag_functions
1284
1285
1286
1287
1288 val get_formatter_stag_functions : unit -> formatter_stag_functions
1289
1290 Return the current semantic tag operation functions of the standard
1291 pretty-printer.
1292
1293
1294 Since 4.08.0
1295
1296
1297
1298
1299 Defining formatters
1300 Defining new formatters permits unrelated output of material in paral‐
1301 lel on several output devices. All the parameters of a formatter are
1302 local to the formatter: right margin, maximum indentation limit, maxi‐
1303 mum number of pretty-printing boxes simultaneously open, ellipsis, and
1304 so on, are specific to each formatter and may be fixed independently.
1305
1306 For instance, given a Buffer.t buffer b , Format.formatter_of_buffer b
1307 returns a new formatter using buffer b as its output device. Simi‐
1308 larly, given a out_channel output channel oc , Format.format‐
1309 ter_of_out_channel oc returns a new formatter using channel oc as its
1310 output device.
1311
1312 Alternatively, given out_funs , a complete set of output functions for
1313 a formatter, then Format.formatter_of_out_functions out_funs computes a
1314 new formatter using those functions for output.
1315
1316 val formatter_of_out_channel : out_channel -> formatter
1317
1318
1319 formatter_of_out_channel oc returns a new formatter writing to the cor‐
1320 responding output channel oc .
1321
1322
1323
1324 val std_formatter : formatter
1325
1326 The standard formatter to write to standard output.
1327
1328 It is defined as Format.formatter_of_out_channel stdout .
1329
1330
1331
1332 val err_formatter : formatter
1333
1334 A formatter to write to standard error.
1335
1336 It is defined as Format.formatter_of_out_channel stderr .
1337
1338
1339
1340 val formatter_of_buffer : Buffer.t -> formatter
1341
1342
1343 formatter_of_buffer b returns a new formatter writing to buffer b . At
1344 the end of pretty-printing, the formatter must be flushed using For‐
1345 mat.pp_print_flush or Format.pp_print_newline , to print all the pend‐
1346 ing material into the buffer.
1347
1348
1349
1350 val stdbuf : Buffer.t
1351
1352 The string buffer in which str_formatter writes.
1353
1354
1355
1356 val str_formatter : formatter
1357
1358 A formatter to output to the Format.stdbuf string buffer.
1359
1360
1361 str_formatter is defined as Format.formatter_of_buffer Format.stdbuf .
1362
1363
1364
1365 val flush_str_formatter : unit -> string
1366
1367 Returns the material printed with str_formatter , flushes the formatter
1368 and resets the corresponding buffer.
1369
1370
1371
1372 val make_formatter : (string -> int -> int -> unit) -> (unit -> unit)
1373 -> formatter
1374
1375
1376 make_formatter out flush returns a new formatter that outputs with
1377 function out , and flushes with function flush .
1378
1379 For instance,
1380 make_formatter
1381 (Stdlib.output oc)
1382 (fun () -> Stdlib.flush oc)
1383
1384 returns a formatter to the out_channel oc .
1385
1386
1387
1388 val formatter_of_out_functions : formatter_out_functions -> formatter
1389
1390
1391 formatter_of_out_functions out_funs returns a new formatter that writes
1392 with the set of output functions out_funs .
1393
1394 See definition of type Format.formatter_out_functions for the meaning
1395 of argument out_funs .
1396
1397
1398 Since 4.06.0
1399
1400
1401
1402
1403 Symbolic pretty-printing
1404 Symbolic pretty-printing is pretty-printing using a symbolic formatter,
1405 i.e. a formatter that outputs symbolic pretty-printing items.
1406
1407 When using a symbolic formatter, all regular pretty-printing activities
1408 occur but output material is symbolic and stored in a buffer of output
1409 items. At the end of pretty-printing, flushing the output buffer al‐
1410 lows post-processing of symbolic output before performing low level
1411 output operations.
1412
1413 In practice, first define a symbolic output buffer b using:
1414
1415 - let sob = make_symbolic_output_buffer () . Then define a symbolic
1416 formatter with:
1417
1418 - let ppf = formatter_of_symbolic_output_buffer sob
1419
1420 Use symbolic formatter ppf as usual, and retrieve symbolic items at end
1421 of pretty-printing by flushing symbolic output buffer sob with:
1422
1423 - flush_symbolic_output_buffer sob .
1424
1425
1426 type symbolic_output_item =
1427 | Output_flush (* symbolic flush command
1428 *)
1429 | Output_newline (* symbolic newline command
1430 *)
1431 | Output_string of string
1432 (* Output_string s : symbolic output for string s
1433
1434 *)
1435 | Output_spaces of int
1436 (* Output_spaces n : symbolic command to output n spaces
1437 *)
1438 | Output_indent of int
1439 (* Output_indent i : symbolic indentation of size i
1440
1441 *)
1442
1443
1444 Items produced by symbolic pretty-printers
1445
1446
1447 Since 4.06.0
1448
1449
1450 type symbolic_output_buffer
1451
1452
1453 The output buffer of a symbolic pretty-printer.
1454
1455
1456 Since 4.06.0
1457
1458
1459
1460 val make_symbolic_output_buffer : unit -> symbolic_output_buffer
1461
1462
1463 make_symbolic_output_buffer () returns a fresh buffer for symbolic out‐
1464 put.
1465
1466
1467 Since 4.06.0
1468
1469
1470
1471 val clear_symbolic_output_buffer : symbolic_output_buffer -> unit
1472
1473
1474 clear_symbolic_output_buffer sob resets buffer sob .
1475
1476
1477 Since 4.06.0
1478
1479
1480
1481 val get_symbolic_output_buffer : symbolic_output_buffer -> sym‐
1482 bolic_output_item list
1483
1484
1485 get_symbolic_output_buffer sob returns the contents of buffer sob .
1486
1487
1488 Since 4.06.0
1489
1490
1491
1492 val flush_symbolic_output_buffer : symbolic_output_buffer -> sym‐
1493 bolic_output_item list
1494
1495
1496 flush_symbolic_output_buffer sob returns the contents of buffer sob and
1497 resets buffer sob . flush_symbolic_output_buffer sob is equivalent to
1498 let items = get_symbolic_output_buffer sob in
1499 clear_symbolic_output_buffer sob; items
1500
1501
1502
1503 Since 4.06.0
1504
1505
1506
1507 val add_symbolic_output_item : symbolic_output_buffer -> symbolic_out‐
1508 put_item -> unit
1509
1510
1511 add_symbolic_output_item sob itm adds item itm to buffer sob .
1512
1513
1514 Since 4.06.0
1515
1516
1517
1518 val formatter_of_symbolic_output_buffer : symbolic_output_buffer ->
1519 formatter
1520
1521
1522 formatter_of_symbolic_output_buffer sob returns a symbolic formatter
1523 that outputs to symbolic_output_buffer sob .
1524
1525
1526 Since 4.06.0
1527
1528
1529
1530
1531 Convenience formatting functions.
1532 val pp_print_list : ?pp_sep:(formatter -> unit -> unit) -> (formatter
1533 -> 'a -> unit) -> formatter -> 'a list -> unit
1534
1535
1536 pp_print_list ?pp_sep pp_v ppf l prints items of list l , using pp_v to
1537 print each item, and calling pp_sep between items ( pp_sep defaults to
1538 Format.pp_print_cut . Does nothing on empty lists.
1539
1540
1541 Since 4.02.0
1542
1543
1544
1545 val pp_print_seq : ?pp_sep:(formatter -> unit -> unit) -> (formatter ->
1546 'a -> unit) -> formatter -> 'a Seq.t -> unit
1547
1548
1549 pp_print_seq ?pp_sep pp_v ppf s prints items of sequence s , using pp_v
1550 to print each item, and calling pp_sep between items ( pp_sep defaults
1551 to Format.pp_print_cut . Does nothing on empty sequences.
1552
1553 This function does not terminate on infinite sequences.
1554
1555
1556 Since 4.12
1557
1558
1559
1560 val pp_print_text : formatter -> string -> unit
1561
1562
1563 pp_print_text ppf s prints s with spaces and newlines respectively
1564 printed using Format.pp_print_space and Format.pp_force_newline .
1565
1566
1567 Since 4.02.0
1568
1569
1570
1571 val pp_print_option : ?none:(formatter -> unit -> unit) -> (formatter
1572 -> 'a -> unit) -> formatter -> 'a option -> unit
1573
1574
1575 pp_print_option ?none pp_v ppf o prints o on ppf using pp_v if o is
1576 Some v and none if it is None . none prints nothing by default.
1577
1578
1579 Since 4.08
1580
1581
1582
1583 val pp_print_result : ok:(formatter -> 'a -> unit) -> error:(formatter
1584 -> 'e -> unit) -> formatter -> ('a, 'e) result -> unit
1585
1586
1587 pp_print_result ~ok ~error ppf r prints r on ppf using ok if r is Ok _
1588 and error if r is Error _ .
1589
1590
1591 Since 4.08
1592
1593
1594
1595 val pp_print_either : left:(formatter -> 'a -> unit) -> right:(format‐
1596 ter -> 'b -> unit) -> formatter -> ('a, 'b) Either.t -> unit
1597
1598
1599 pp_print_either ~left ~right ppf e prints e on ppf using left if e is
1600 Either.Left _ and right if e is Either.Right _ .
1601
1602
1603 Since 4.13
1604
1605
1606
1607
1608 Formatted pretty-printing
1609 Module Format provides a complete set of printf like functions for
1610 pretty-printing using format string specifications.
1611
1612 Specific annotations may be added in the format strings to give
1613 pretty-printing commands to the pretty-printing engine.
1614
1615 Those annotations are introduced in the format strings using the @
1616 character. For instance, @ means a space break, @, means a cut, @[
1617 opens a new box, and @] closes the last open box.
1618
1619 val fprintf : formatter -> ('a, formatter, unit) format -> 'a
1620
1621
1622
1623
1624
1625 fprintf ff fmt arg1 ... argN formats the arguments arg1 to argN accord‐
1626 ing to the format string fmt , and outputs the resulting string on the
1627 formatter ff .
1628
1629 The format string fmt is a character string which contains three types
1630 of objects: plain characters and conversion specifications as specified
1631 in the Printf module, and pretty-printing indications specific to the
1632 Format module.
1633
1634 The pretty-printing indication characters are introduced by a @ charac‐
1635 ter, and their meanings are:
1636
1637 - @[ : open a pretty-printing box. The type and offset of the box may
1638 be optionally specified with the following syntax: the < character,
1639 followed by an optional box type indication, then an optional integer
1640 offset, and the closing > character. Pretty-printing box type is one
1641 of h , v , hv , b , or hov . ' h ' stands for an 'horizontal'
1642 pretty-printing box, ' v ' stands for a 'vertical' pretty-printing box,
1643 ' hv ' stands for an 'horizontal/vertical' pretty-printing box, ' b '
1644 stands for an 'horizontal-or-vertical' pretty-printing box demonstrat‐
1645 ing indentation, ' hov ' stands a simple 'horizontal-or-vertical'
1646 pretty-printing box. For instance, @[<hov 2> opens an 'horizon‐
1647 tal-or-vertical' pretty-printing box with indentation 2 as obtained
1648 with open_hovbox 2 . For more details about pretty-printing boxes, see
1649 the various box opening functions open_*box .
1650
1651 - @] : close the most recently opened pretty-printing box.
1652
1653 - @, : output a 'cut' break hint, as with print_cut () .
1654
1655 - @ : output a 'space' break hint, as with print_space () .
1656
1657 - @; : output a 'full' break hint as with print_break . The nspaces and
1658 offset parameters of the break hint may be optionally specified with
1659 the following syntax: the < character, followed by an integer nspaces
1660 value, then an integer offset , and a closing > character. If no pa‐
1661 rameters are provided, the good break defaults to a 'space' break hint.
1662
1663 - @. : flush the pretty-printer and split the line, as with print_new‐
1664 line () .
1665
1666 - @<n> : print the following item as if it were of length n . Hence,
1667 printf "@<0>%s" arg prints arg as a zero length string. If @<n> is not
1668 followed by a conversion specification, then the following character of
1669 the format is printed as if it were of length n .
1670
1671 - @{ : open a semantic tag. The name of the tag may be optionally spec‐
1672 ified with the following syntax: the < character, followed by an op‐
1673 tional string specification, and the closing > character. The string
1674 specification is any character string that does not contain the closing
1675 character '>' . If omitted, the tag name defaults to the empty string.
1676 For more details about semantic tags, see the functions For‐
1677 mat.open_stag and Format.close_stag .
1678
1679 - @} : close the most recently opened semantic tag.
1680
1681 - @? : flush the pretty-printer as with print_flush () . This is
1682 equivalent to the conversion %! .
1683
1684 - @\n : force a newline, as with force_newline () , not the normal way
1685 of pretty-printing, you should prefer using break hints inside a verti‐
1686 cal pretty-printing box.
1687
1688 Note: To prevent the interpretation of a @ character as a pretty-print‐
1689 ing indication, escape it with a % character. Old quotation mode @@ is
1690 deprecated since it is not compatible with formatted input interpreta‐
1691 tion of character '@' .
1692
1693 Example: printf "@[%s@ %d@]@." "x =" 1 is equivalent to open_box ();
1694 print_string "x ="; print_space ();
1695 print_int 1; close_box (); print_newline () . It prints x = 1
1696 within a pretty-printing 'horizontal-or-vertical' box.
1697
1698 val printf : ('a, formatter, unit) format -> 'a
1699
1700 Same as fprintf above, but output on std_formatter .
1701
1702
1703
1704 val eprintf : ('a, formatter, unit) format -> 'a
1705
1706 Same as fprintf above, but output on err_formatter .
1707
1708
1709
1710 val sprintf : ('a, unit, string) format -> 'a
1711
1712 Same as printf above, but instead of printing on a formatter, returns a
1713 string containing the result of formatting the arguments. Note that
1714 the pretty-printer queue is flushed at the end of each call to sprintf
1715 .
1716
1717 In case of multiple and related calls to sprintf to output material on
1718 a single string, you should consider using fprintf with the predefined
1719 formatter str_formatter and call flush_str_formatter () to get the fi‐
1720 nal result.
1721
1722 Alternatively, you can use Format.fprintf with a formatter writing to a
1723 buffer of your own: flushing the formatter and the buffer at the end of
1724 pretty-printing returns the desired string.
1725
1726
1727
1728 val asprintf : ('a, formatter, unit, string) format4 -> 'a
1729
1730 Same as printf above, but instead of printing on a formatter, returns a
1731 string containing the result of formatting the arguments. The type of
1732 asprintf is general enough to interact nicely with %a conversions.
1733
1734
1735 Since 4.01.0
1736
1737
1738
1739 val dprintf : ('a, formatter, unit, formatter -> unit) format4 -> 'a
1740
1741 Same as Format.fprintf , except the formatter is the last argument.
1742 dprintf "..." a b c is a function of type formatter -> unit which can
1743 be given to a format specifier %t .
1744
1745 This can be used as a replacement for Format.asprintf to delay format‐
1746 ting decisions. Using the string returned by Format.asprintf in a for‐
1747 matting context forces formatting decisions to be taken in isolation,
1748 and the final string may be created prematurely. Format.dprintf allows
1749 delay of formatting decisions until the final formatting context is
1750 known. For example:
1751 let t = Format.dprintf "%i@ %i@ %i" 1 2 3 in
1752 ...
1753 Format.printf "@[<v>%t@]" t
1754
1755
1756
1757 Since 4.08.0
1758
1759
1760
1761 val ifprintf : formatter -> ('a, formatter, unit) format -> 'a
1762
1763 Same as fprintf above, but does not print anything. Useful to ignore
1764 some material when conditionally printing.
1765
1766
1767 Since 3.10.0
1768
1769
1770
1771
1772 Formatted Pretty-Printing with continuations.
1773
1774 val kfprintf : (formatter -> 'a) -> formatter -> ('b, formatter, unit,
1775 'a) format4 -> 'b
1776
1777 Same as fprintf above, but instead of returning immediately, passes the
1778 formatter to its first argument at the end of printing.
1779
1780
1781
1782 val kdprintf : ((formatter -> unit) -> 'a) -> ('b, formatter, unit, 'a)
1783 format4 -> 'b
1784
1785 Same as Format.dprintf above, but instead of returning immediately,
1786 passes the suspended printer to its first argument at the end of print‐
1787 ing.
1788
1789
1790 Since 4.08.0
1791
1792
1793
1794 val ikfprintf : (formatter -> 'a) -> formatter -> ('b, formatter, unit,
1795 'a) format4 -> 'b
1796
1797 Same as kfprintf above, but does not print anything. Useful to ignore
1798 some material when conditionally printing.
1799
1800
1801 Since 3.12.0
1802
1803
1804
1805 val ksprintf : (string -> 'a) -> ('b, unit, string, 'a) format4 -> 'b
1806
1807 Same as sprintf above, but instead of returning the string, passes it
1808 to the first argument.
1809
1810
1811
1812 val kasprintf : (string -> 'a) -> ('b, formatter, unit, 'a) format4 ->
1813 'b
1814
1815 Same as asprintf above, but instead of returning the string, passes it
1816 to the first argument.
1817
1818
1819 Since 4.03
1820
1821
1822
1823
1824 Deprecated
1825 val bprintf : Buffer.t -> ('a, formatter, unit) format -> 'a
1826
1827 Deprecated. This function is error prone. Do not use it. This func‐
1828 tion is neither compositional nor incremental, since it flushes the
1829 pretty-printer queue at each call.
1830
1831 If you need to print to some buffer b , you must first define a format‐
1832 ter writing to b , using let to_b = formatter_of_buffer b ; then use
1833 regular calls to Format.fprintf with formatter to_b .
1834
1835
1836
1837 val kprintf : (string -> 'a) -> ('b, unit, string, 'a) format4 -> 'b
1838
1839 Deprecated. An alias for ksprintf .
1840
1841
1842
1843 val set_all_formatter_output_functions : out:(string -> int -> int ->
1844 unit) -> flush:(unit -> unit) -> newline:(unit -> unit) -> spaces:(int
1845 -> unit) -> unit
1846
1847 Deprecated. Subsumed by set_formatter_out_functions .
1848
1849
1850
1851 val get_all_formatter_output_functions : unit -> (string -> int -> int
1852 -> unit) * (unit -> unit) * (unit -> unit) * (int -> unit)
1853
1854 Deprecated. Subsumed by get_formatter_out_functions .
1855
1856
1857
1858 val pp_set_all_formatter_output_functions : formatter -> out:(string ->
1859 int -> int -> unit) -> flush:(unit -> unit) -> newline:(unit -> unit)
1860 -> spaces:(int -> unit) -> unit
1861
1862 Deprecated. Subsumed by pp_set_formatter_out_functions .
1863
1864
1865
1866 val pp_get_all_formatter_output_functions : formatter -> unit ->
1867 (string -> int -> int -> unit) * (unit -> unit) * (unit -> unit) * (int
1868 -> unit)
1869
1870 Deprecated. Subsumed by pp_get_formatter_out_functions .
1871
1872
1873
1874
1875 String tags
1876 val pp_open_tag : formatter -> tag -> unit
1877
1878 Deprecated. Subsumed by Format.pp_open_stag .
1879
1880
1881
1882 val open_tag : tag -> unit
1883
1884 Deprecated. Subsumed by Format.open_stag .
1885
1886
1887
1888 val pp_close_tag : formatter -> unit -> unit
1889
1890 Deprecated. Subsumed by Format.pp_close_stag .
1891
1892
1893
1894 val close_tag : unit -> unit
1895
1896 Deprecated. Subsumed by Format.close_stag .
1897
1898
1899 type formatter_tag_functions = {
1900 mark_open_tag : tag -> string ;
1901 mark_close_tag : tag -> string ;
1902 print_open_tag : tag -> unit ;
1903 print_close_tag : tag -> unit ;
1904 }
1905
1906
1907 Deprecated. Subsumed by Format.formatter_stag_functions .
1908
1909
1910
1911 val pp_set_formatter_tag_functions : formatter -> formatter_tag_func‐
1912 tions -> unit
1913
1914 Deprecated. Subsumed by Format.pp_set_formatter_stag_functions .
1915
1916
1917 This function will erase non-string tag formatting functions.
1918
1919
1920
1921 val set_formatter_tag_functions : formatter_tag_functions -> unit
1922
1923 Deprecated. Subsumed by Format.set_formatter_stag_functions .
1924
1925
1926
1927 val pp_get_formatter_tag_functions : formatter -> unit -> format‐
1928 ter_tag_functions
1929
1930 Deprecated. Subsumed by Format.pp_get_formatter_stag_functions .
1931
1932
1933
1934 val get_formatter_tag_functions : unit -> formatter_tag_functions
1935
1936 Deprecated. Subsumed by Format.get_formatter_stag_functions .
1937
1938
1939
1940
1941
1942OCamldoc 2022-07-22 Stdlib.Format(3)