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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Guile Reference Manual. | |
6ea30487 | 3 | @c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009, 2010 |
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4 | @c Free Software Foundation, Inc. |
5 | @c See the file guile.texi for copying conditions. | |
6 | ||
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7 | @node Options and Config |
8 | @section Configuration, Features and Runtime Options | |
9 | ||
10 | Why is my Guile different from your Guile? There are three kinds of | |
11 | possible variation: | |
12 | ||
13 | @itemize @bullet | |
14 | @item | |
15 | build differences --- different versions of the Guile source code, | |
16 | installation directories, configuration flags that control pieces of | |
17 | functionality being included or left out, etc. | |
18 | ||
19 | @item | |
20 | differences in dynamically loaded code --- behaviour and features | |
21 | provided by modules that can be dynamically loaded into a running Guile | |
22 | ||
23 | @item | |
24 | different runtime options --- some of the options that are provided for | |
25 | controlling Guile's behaviour may be set differently. | |
26 | @end itemize | |
27 | ||
28 | Guile provides ``introspective'' variables and procedures to query all | |
29 | of these possible variations at runtime. For runtime options, it also | |
30 | provides procedures to change the settings of options and to obtain | |
31 | documentation on what the options mean. | |
32 | ||
33 | @menu | |
34 | * Build Config:: Build and installation configuration. | |
35 | * Feature Tracking:: Available features in the Guile process. | |
36 | * Runtime Options:: Controlling Guile's runtime behaviour. | |
37 | @end menu | |
38 | ||
39 | ||
40 | @node Build Config | |
41 | @subsection Configuration, Build and Installation | |
42 | ||
43 | The following procedures and variables provide information about how | |
44 | Guile was configured, built and installed on your system. | |
45 | ||
46 | @deffn {Scheme Procedure} version | |
47 | @deffnx {Scheme Procedure} effective-version | |
48 | @deffnx {Scheme Procedure} major-version | |
49 | @deffnx {Scheme Procedure} minor-version | |
50 | @deffnx {Scheme Procedure} micro-version | |
51 | @deffnx {C Function} scm_version () | |
52 | @deffnx {C Function} scm_effective_version () | |
53 | @deffnx {C Function} scm_major_version () | |
54 | @deffnx {C Function} scm_minor_version () | |
55 | @deffnx {C Function} scm_micro_version () | |
56 | Return a string describing Guile's full version number, effective | |
57 | version number, major, minor or micro version number, respectively. | |
58 | The @code{effective-version} function returns the version name that | |
59 | should remain unchanged during a stable series. Currently that means | |
60 | that it omits the micro version. The effective version should be used | |
61 | for items like the versioned share directory name | |
62 | i.e. @file{/usr/share/guile/1.6/} | |
63 | ||
64 | @lisp | |
65 | (version) @result{} "1.6.0" | |
66 | (effective-version) @result{} "1.6" | |
67 | (major-version) @result{} "1" | |
68 | (minor-version) @result{} "6" | |
69 | (micro-version) @result{} "0" | |
70 | @end lisp | |
71 | @end deffn | |
72 | ||
73 | @deffn {Scheme Procedure} %package-data-dir | |
74 | @deffnx {C Function} scm_sys_package_data_dir () | |
75 | Return the name of the directory under which Guile Scheme files in | |
76 | general are stored. On Unix-like systems, this is usually | |
77 | @file{/usr/local/share/guile} or @file{/usr/share/guile}. | |
78 | @end deffn | |
79 | ||
80 | @deffn {Scheme Procedure} %library-dir | |
81 | @deffnx {C Function} scm_sys_library_dir () | |
82 | Return the name of the directory where the Guile Scheme files that | |
83 | belong to the core Guile installation (as opposed to files from a 3rd | |
45867c2a | 84 | party package) are installed. On Unix-like systems this is usually |
07d83abe | 85 | @file{/usr/local/share/guile/<GUILE_EFFECTIVE_VERSION>} or |
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86 | @file{/usr/share/guile/<GUILE_EFFECTIVE_VERSION>}; |
87 | ||
88 | @noindent for example @file{/usr/local/share/guile/1.6}. | |
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89 | @end deffn |
90 | ||
91 | @deffn {Scheme Procedure} %site-dir | |
92 | @deffnx {C Function} scm_sys_site_dir () | |
93 | Return the name of the directory where Guile Scheme files specific to | |
94 | your site should be installed. On Unix-like systems, this is usually | |
95 | @file{/usr/local/share/guile/site} or @file{/usr/share/guile/site}. | |
96 | @end deffn | |
97 | ||
98 | @cindex GUILE_LOAD_PATH | |
99 | @defvar %load-path | |
100 | List of directories which should be searched for Scheme modules and | |
101 | libraries. @code{%load-path} is initialized when Guile starts up to | |
8370b00b | 102 | @code{(list (%site-dir) (%library-dir) (%package-data-dir))}, |
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103 | prepended with the contents of the GUILE_LOAD_PATH environment variable, |
104 | if it is set. | |
105 | @end defvar | |
106 | ||
107 | @deffn {Scheme Procedure} parse-path path [tail] | |
108 | @deffnx {C Function} scm_parse_path (path, tail) | |
109 | Parse @var{path}, which is expected to be a colon-separated | |
110 | string, into a list and return the resulting list with | |
111 | @var{tail} appended. If @var{path} is @code{#f}, @var{tail} | |
112 | is returned. | |
113 | @end deffn | |
114 | ||
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115 | @deffn {Scheme Procedure} search-path path filename [extensions [require-exts?]] |
116 | @deffnx {C Function} scm_search_path (path, filename, rest) | |
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117 | Search @var{path} for a directory containing a file named |
118 | @var{filename}. The file must be readable, and not a directory. | |
119 | If we find one, return its full filename; otherwise, return | |
120 | @code{#f}. If @var{filename} is absolute, return it unchanged. | |
121 | If given, @var{extensions} is a list of strings; for each | |
122 | directory in @var{path}, we search for @var{filename} | |
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123 | concatenated with each @var{extension}. If @var{require-exts?} |
124 | is true, require that the returned file name have one of the | |
125 | given extensions; if @var{require-exts?} is not given, it | |
126 | defaults to @code{#f}. | |
127 | ||
128 | For compatibility with Guile 1.8 and earlier, the C function takes only | |
129 | three arguments | |
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130 | @end deffn |
131 | ||
132 | @defvar %guile-build-info | |
133 | Alist of information collected during the building of a particular | |
134 | Guile. Entries can be grouped into one of several categories: | |
135 | directories, env vars, and versioning info. | |
136 | ||
137 | Briefly, here are the keys in @code{%guile-build-info}, by group: | |
138 | ||
139 | @cindex @code{srcdir} | |
140 | @cindex @code{top_srcdir} | |
141 | @cindex @code{prefix} | |
142 | @cindex @code{exec_prefix} | |
143 | @cindex @code{bindir} | |
144 | @cindex @code{sbindir} | |
145 | @cindex @code{libexecdir} | |
146 | @cindex @code{datadir} | |
147 | @cindex @code{sysconfdir} | |
148 | @cindex @code{sharedstatedir} | |
149 | @cindex @code{localstatedir} | |
150 | @cindex @code{libdir} | |
151 | @cindex @code{infodir} | |
152 | @cindex @code{mandir} | |
153 | @cindex @code{includedir} | |
154 | @cindex @code{pkgdatadir} | |
155 | @cindex @code{pkglibdir} | |
156 | @cindex @code{pkgincludedir} | |
157 | @table @asis | |
158 | @item directories | |
159 | srcdir, top_srcdir, prefix, exec_prefix, bindir, sbindir, libexecdir, | |
160 | datadir, sysconfdir, sharedstatedir, localstatedir, libdir, infodir, | |
161 | mandir, includedir, pkgdatadir, pkglibdir, pkgincludedir | |
162 | @cindex @code{LIBS} | |
163 | @item env vars | |
164 | LIBS | |
165 | @cindex @code{guileversion} | |
166 | @cindex @code{libguileinterface} | |
167 | @cindex @code{buildstamp} | |
168 | @item versioning info | |
169 | guileversion, libguileinterface, buildstamp | |
170 | @end table | |
171 | ||
172 | Values are all strings. The value for @code{LIBS} is typically found | |
173 | also as a part of "guile-config link" output. The value for | |
174 | @code{guileversion} has form X.Y.Z, and should be the same as returned | |
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175 | by @code{(version)}. The value for @code{libguileinterface} is |
176 | libtool compatible and has form CURRENT:REVISION:AGE | |
177 | (@pxref{Versioning,, Library interface versions, libtool, GNU | |
178 | Libtool}). The value for @code{buildstamp} is the output of the | |
a6025413 | 179 | command @samp{date -u +'%Y-%m-%d %T'} (UTC). |
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180 | |
181 | In the source, @code{%guile-build-info} is initialized from | |
182 | libguile/libpath.h, which is completely generated, so deleting this file | |
183 | before a build guarantees up-to-date values for that build. | |
184 | @end defvar | |
185 | ||
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186 | @cindex GNU triplet |
187 | @cindex canonical host type | |
188 | ||
189 | @defvar %host-type | |
190 | The canonical host type (GNU triplet) of the host Guile was configured | |
191 | for, e.g., @code{"x86_64-unknown-linux-gnu"} (@pxref{Canonicalizing,,, | |
192 | autoconf, The GNU Autoconf Manual}). | |
193 | @end defvar | |
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194 | |
195 | @node Feature Tracking | |
196 | @subsection Feature Tracking | |
197 | ||
198 | Guile has a Scheme level variable @code{*features*} that keeps track to | |
199 | some extent of the features that are available in a running Guile. | |
200 | @code{*features*} is a list of symbols, for example @code{threads}, each | |
201 | of which describes a feature of the running Guile process. | |
202 | ||
203 | @defvar *features* | |
204 | A list of symbols describing available features of the Guile process. | |
205 | @end defvar | |
206 | ||
207 | You shouldn't modify the @code{*features*} variable directly using | |
208 | @code{set!}. Instead, see the procedures that are provided for this | |
209 | purpose in the following subsection. | |
210 | ||
211 | @menu | |
212 | * Feature Manipulation:: Checking for and advertising features. | |
213 | * Common Feature Symbols:: Commonly available features. | |
214 | @end menu | |
215 | ||
216 | ||
217 | @node Feature Manipulation | |
218 | @subsubsection Feature Manipulation | |
219 | ||
220 | To check whether a particular feature is available, use the | |
221 | @code{provided?} procedure: | |
222 | ||
223 | @deffn {Scheme Procedure} provided? feature | |
224 | @deffnx {Deprecated Scheme Procedure} feature? feature | |
225 | Return @code{#t} if the specified @var{feature} is available, otherwise | |
226 | @code{#f}. | |
227 | @end deffn | |
228 | ||
229 | To advertise a feature from your own Scheme code, you can use the | |
230 | @code{provide} procedure: | |
231 | ||
232 | @deffn {Scheme Procedure} provide feature | |
233 | Add @var{feature} to the list of available features in this Guile | |
234 | process. | |
235 | @end deffn | |
236 | ||
237 | For C code, the equivalent function takes its feature name as a | |
238 | @code{char *} argument for convenience: | |
239 | ||
240 | @deftypefn {C Function} void scm_add_feature (const char *str) | |
241 | Add a symbol with name @var{str} to the list of available features in | |
242 | this Guile process. | |
243 | @end deftypefn | |
244 | ||
245 | ||
246 | @node Common Feature Symbols | |
247 | @subsubsection Common Feature Symbols | |
248 | ||
249 | In general, a particular feature may be available for one of two | |
250 | reasons. Either because the Guile library was configured and compiled | |
251 | with that feature enabled --- i.e. the feature is built into the library | |
252 | on your system. Or because some C or Scheme code that was dynamically | |
253 | loaded by Guile has added that feature to the list. | |
254 | ||
255 | In the first category, here are the features that the current version of | |
256 | Guile may define (depending on how it is built), and what they mean. | |
257 | ||
258 | @table @code | |
259 | @item array | |
260 | Indicates support for arrays (@pxref{Arrays}). | |
261 | ||
262 | @item array-for-each | |
263 | Indicates availability of @code{array-for-each} and other array mapping | |
40499598 | 264 | procedures (@pxref{Arrays}). |
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265 | |
266 | @item char-ready? | |
267 | Indicates that the @code{char-ready?} function is available | |
268 | (@pxref{Reading}). | |
269 | ||
270 | @item complex | |
271 | Indicates support for complex numbers. | |
272 | ||
273 | @item current-time | |
274 | Indicates availability of time-related functions: @code{times}, | |
275 | @code{get-internal-run-time} and so on (@pxref{Time}). | |
276 | ||
277 | @item debug-extensions | |
278 | Indicates that the debugging evaluator is available, together with the | |
279 | options for controlling it. | |
280 | ||
281 | @item delay | |
282 | Indicates support for promises (@pxref{Delayed Evaluation}). | |
283 | ||
284 | @item EIDs | |
285 | Indicates that the @code{geteuid} and @code{getegid} really return | |
286 | effective user and group IDs (@pxref{Processes}). | |
287 | ||
288 | @item inexact | |
289 | Indicates support for inexact numbers. | |
290 | ||
291 | @item i/o-extensions | |
292 | Indicates availability of the following extended I/O procedures: | |
293 | @code{ftell}, @code{redirect-port}, @code{dup->fdes}, @code{dup2}, | |
294 | @code{fileno}, @code{isatty?}, @code{fdopen}, | |
295 | @code{primitive-move->fdes} and @code{fdes->ports} (@pxref{Ports and | |
296 | File Descriptors}). | |
297 | ||
298 | @item net-db | |
299 | Indicates availability of network database functions: | |
300 | @code{scm_gethost}, @code{scm_getnet}, @code{scm_getproto}, | |
301 | @code{scm_getserv}, @code{scm_sethost}, @code{scm_setnet}, @code{scm_setproto}, | |
302 | @code{scm_setserv}, and their `byXXX' variants (@pxref{Network | |
303 | Databases}). | |
304 | ||
305 | @item posix | |
306 | Indicates support for POSIX functions: @code{pipe}, @code{getgroups}, | |
307 | @code{kill}, @code{execl} and so on (@pxref{POSIX}). | |
308 | ||
309 | @item random | |
310 | Indicates availability of random number generation functions: | |
311 | @code{random}, @code{copy-random-state}, @code{random-uniform} and so on | |
312 | (@pxref{Random}). | |
313 | ||
314 | @item reckless | |
315 | Indicates that Guile was built with important checks omitted --- you | |
316 | should never see this! | |
317 | ||
318 | @item regex | |
319 | Indicates support for POSIX regular expressions using | |
320 | @code{make-regexp}, @code{regexp-exec} and friends (@pxref{Regexp | |
321 | Functions}). | |
322 | ||
323 | @item socket | |
324 | Indicates availability of socket-related functions: @code{socket}, | |
325 | @code{bind}, @code{connect} and so on (@pxref{Network Sockets and | |
326 | Communication}). | |
327 | ||
328 | @item sort | |
329 | Indicates availability of sorting and merging functions | |
330 | (@pxref{Sorting}). | |
331 | ||
332 | @item system | |
333 | Indicates that the @code{system} function is available | |
334 | (@pxref{Processes}). | |
335 | ||
336 | @item threads | |
337 | Indicates support for multithreading (@pxref{Threads}). | |
338 | ||
339 | @item values | |
340 | Indicates support for multiple return values using @code{values} and | |
341 | @code{call-with-values} (@pxref{Multiple Values}). | |
342 | @end table | |
343 | ||
344 | Available features in the second category depend, by definition, on what | |
345 | additional code your Guile process has loaded in. The following table | |
346 | lists features that you might encounter for this reason. | |
347 | ||
348 | @table @code | |
349 | @item defmacro | |
350 | Indicates that the @code{defmacro} macro is available (@pxref{Macros}). | |
351 | ||
352 | @item describe | |
353 | Indicates that the @code{(oop goops describe)} module has been loaded, | |
354 | which provides a procedure for describing the contents of GOOPS | |
355 | instances. | |
356 | ||
357 | @item readline | |
358 | Indicates that Guile has loaded in Readline support, for command line | |
359 | editing (@pxref{Readline Support}). | |
360 | ||
361 | @item record | |
362 | Indicates support for record definition using @code{make-record-type} | |
363 | and friends (@pxref{Records}). | |
364 | @end table | |
365 | ||
366 | Although these tables may seem exhaustive, it is probably unwise in | |
367 | practice to rely on them, as the correspondences between feature symbols | |
368 | and available procedures/behaviour are not strictly defined. If you are | |
369 | writing code that needs to check for the existence of some procedure, it | |
370 | is probably safer to do so directly using the @code{defined?} procedure | |
371 | than to test for the corresponding feature using @code{provided?}. | |
372 | ||
373 | ||
374 | @node Runtime Options | |
375 | @subsection Runtime Options | |
376 | ||
377 | Guile's runtime behaviour can be modified by setting options. For | |
378 | example, is the language that Guile accepts case sensitive, or should | |
379 | the debugger automatically show a backtrace on error? | |
380 | ||
381 | Guile has two levels of interface for managing options: a low-level | |
382 | control interface, and a user-level interface which allows the enabling | |
383 | or disabling of options. | |
384 | ||
385 | Moreover, the options are classified in groups according to whether they | |
386 | configure @emph{reading}, @emph{printing}, @emph{debugging} or | |
387 | @emph{evaluating}. | |
388 | ||
389 | @menu | |
390 | * Low level options interfaces:: | |
391 | * User level options interfaces:: | |
392 | * Reader options:: | |
393 | * Printing options:: | |
394 | * Debugger options:: | |
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395 | * Examples of option use:: |
396 | @end menu | |
397 | ||
398 | ||
399 | @node Low level options interfaces | |
400 | @subsubsection Low Level Options Interfaces | |
401 | ||
402 | @deffn {Scheme Procedure} read-options-interface [setting] | |
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403 | @deffnx {Scheme Procedure} print-options-interface [setting] |
404 | @deffnx {Scheme Procedure} debug-options-interface [setting] | |
07d83abe | 405 | @deffnx {C Function} scm_read_options (setting) |
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406 | @deffnx {C Function} scm_print_options (setting) |
407 | @deffnx {C Function} scm_debug_options (setting) | |
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408 | If one of these procedures is called with no arguments (or with |
409 | @code{setting == SCM_UNDEFINED} in C code), it returns a list describing | |
410 | the current setting of the read, eval, print, debug or evaluator traps | |
411 | options respectively. The setting of a boolean option is indicated | |
412 | simply by the presence or absence of the option symbol in the list. The | |
413 | setting of a non-boolean option is indicated by the presence of the | |
414 | option symbol immediately followed by the option's current value. | |
415 | ||
416 | If called with a list argument, these procedures interpret the list as | |
417 | an option setting and modify the relevant options accordingly. [FIXME | |
418 | --- this glosses over a lot of details!] | |
419 | ||
420 | If called with any other argument, such as @code{'help}, these | |
421 | procedures return a list of entries like @code{(@var{OPTION-SYMBOL} | |
422 | @var{DEFAULT-VALUE} @var{DOC-STRING})}, with each entry giving the | |
423 | default value and documentation for each option symbol in the relevant | |
424 | set of options. | |
425 | @end deffn | |
426 | ||
427 | ||
428 | @node User level options interfaces | |
429 | @subsubsection User Level Options Interfaces | |
430 | ||
431 | @c @deftp {Data type} scm_option | |
432 | @c @code{scm_option} is used to represent run time options. It can be a | |
433 | @c @emph{boolean} type, in which case the option will be set by the strings | |
434 | @c @code{"yes"} and @code{"no"}. It can be a | |
435 | @c @end deftp | |
436 | ||
437 | @c NJFIXME | |
438 | @deffn {Scheme Procedure} <group>-options [arg] | |
439 | @deffnx {Scheme Procedure} read-options [arg] | |
440 | @deffnx {Scheme Procedure} print-options [arg] | |
441 | @deffnx {Scheme Procedure} debug-options [arg] | |
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442 | These functions list the options in their group. The optional argument |
443 | @var{arg} is a symbol which modifies the form in which the options are | |
444 | presented. | |
445 | ||
446 | With no arguments, @code{<group>-options} returns the values of the | |
447 | options in that particular group. If @var{arg} is @code{'help}, a | |
448 | description of each option is given. If @var{arg} is @code{'full}, | |
449 | programmers' options are also shown. | |
450 | ||
451 | @var{arg} can also be a list representing the state of all options. In | |
452 | this case, the list contains single symbols (for enabled boolean | |
453 | options) and symbols followed by values. | |
454 | @end deffn | |
455 | [FIXME: I don't think 'full is ever any different from 'help. What's | |
456 | up?] | |
457 | ||
458 | @c NJFIXME | |
459 | @deffn {Scheme Procedure} <group>-enable option-symbol | |
460 | @deffnx {Scheme Procedure} read-enable option-symbol | |
461 | @deffnx {Scheme Procedure} print-enable option-symbol | |
462 | @deffnx {Scheme Procedure} debug-enable option-symbol | |
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463 | These functions set the specified @var{option-symbol} in their options |
464 | group. They only work if the option is boolean, and throw an error | |
465 | otherwise. | |
466 | @end deffn | |
467 | ||
468 | @c NJFIXME | |
469 | @deffn {Scheme Procedure} <group>-disable option-symbol | |
470 | @deffnx {Scheme Procedure} read-disable option-symbol | |
471 | @deffnx {Scheme Procedure} print-disable option-symbol | |
472 | @deffnx {Scheme Procedure} debug-disable option-symbol | |
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473 | These functions turn off the specified @var{option-symbol} in their |
474 | options group. They only work if the option is boolean, and throw an | |
475 | error otherwise. | |
476 | @end deffn | |
477 | ||
478 | @c NJFIXME | |
479 | @deffn syntax <group>-set! option-symbol value | |
480 | @deffnx syntax read-set! option-symbol value | |
481 | @deffnx syntax print-set! option-symbol value | |
482 | @deffnx syntax debug-set! option-symbol value | |
07d83abe MV |
483 | These functions set a non-boolean @var{option-symbol} to the specified |
484 | @var{value}. | |
485 | @end deffn | |
486 | ||
487 | ||
488 | @node Reader options | |
489 | @subsubsection Reader options | |
490 | @cindex options - read | |
491 | @cindex read options | |
492 | ||
493 | Here is the list of reader options generated by typing | |
494 | @code{(read-options 'full)} in Guile. You can also see the default | |
495 | values. | |
496 | ||
497 | @smalllisp | |
ef4cbc08 | 498 | keywords #f Style of keyword recognition: #f, 'prefix or 'postfix |
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499 | case-insensitive no Convert symbols to lower case. |
500 | positions yes Record positions of source code expressions. | |
501 | copy no Copy source code expressions. | |
0f3a70cf | 502 | r6rs-hex-escapes no Use R6RS-style string hex escapes |
07d83abe MV |
503 | @end smalllisp |
504 | ||
505 | Notice that while Standard Scheme is case insensitive, to ease | |
506 | translation of other Lisp dialects, notably Emacs Lisp, into Guile, | |
507 | Guile is case-sensitive by default. | |
508 | ||
509 | To make Guile case insensitive, you can type | |
510 | ||
aba0dff5 | 511 | @lisp |
07d83abe | 512 | (read-enable 'case-insensitive) |
aba0dff5 | 513 | @end lisp |
07d83abe | 514 | |
6ea30487 | 515 | For more information on the effect of the @code{r6rs-hex-escapes} option, see |
0f3a70cf | 516 | (@pxref{String Syntax}). |
6ea30487 | 517 | |
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518 | @node Printing options |
519 | @subsubsection Printing options | |
520 | ||
521 | Here is the list of print options generated by typing | |
522 | @code{(print-options 'full)} in Guile. You can also see the default | |
523 | values. | |
524 | ||
525 | @smallexample | |
227eafdb MV |
526 | quote-keywordish-symbols reader How to print symbols that have a colon |
527 | as their first or last character. The | |
528 | value '#f' does not quote the colons; | |
529 | '#t' quotes them; 'reader' quotes | |
530 | them when the reader option | |
531 | 'keywords' is not '#f'. | |
532 | ||
533 | highlight-prefix @{ The string to print before highlighted values. | |
534 | highlight-suffix @} The string to print after highlighted values. | |
535 | ||
536 | source no Print closures with source. | |
537 | closure-hook #f Hook for printing closures. | |
07d83abe MV |
538 | @end smallexample |
539 | ||
540 | ||
07d83abe MV |
541 | @node Debugger options |
542 | @subsubsection Debugger options | |
543 | ||
544 | Here is the list of print options generated by typing | |
545 | @code{(debug-options 'full)} in Guile. You can also see the default | |
546 | values. | |
547 | ||
548 | @smallexample | |
549 | stack 20000 Stack size limit (0 = no check). | |
550 | debug yes Use the debugging evaluator. | |
551 | backtrace no Show backtrace on error. | |
552 | depth 20 Maximal length of printed backtrace. | |
553 | maxdepth 1000 Maximal number of stored backtrace frames. | |
554 | frames 3 Maximum number of tail-recursive frames in backtrace. | |
555 | indent 10 Maximal indentation in backtrace. | |
556 | backwards no Display backtrace in anti-chronological order. | |
557 | procnames yes Record procedure names at definition. | |
558 | trace no *Trace mode. | |
559 | breakpoints no *Check for breakpoints. | |
31e2cc50 | 560 | cheap yes *This option is now obsolete. Setting it has no effect. |
07d83abe MV |
561 | @end smallexample |
562 | ||
563 | @subsubheading Stack overflow | |
564 | ||
565 | @cindex overflow, stack | |
566 | @cindex stack overflow | |
567 | Stack overflow errors are caused by a computation trying to use more | |
568 | stack space than has been enabled by the @code{stack} option. They are | |
569 | reported like this: | |
570 | ||
571 | @lisp | |
572 | (non-tail-recursive-factorial 500) | |
573 | @print{} | |
574 | ERROR: Stack overflow | |
575 | ABORT: (stack-overflow) | |
576 | @end lisp | |
577 | ||
578 | If you get an error like this, you can either try rewriting your code to | |
579 | use less stack space, or increase the maximum stack size. To increase | |
580 | the maximum stack size, use @code{debug-set!}, for example: | |
581 | ||
582 | @lisp | |
583 | (debug-set! stack 200000) | |
584 | @result{} | |
45867c2a NJ |
585 | (show-file-name #t stack 200000 debug backtrace depth 20 |
586 | maxdepth 1000 frames 3 indent 10 width 79 procnames cheap) | |
07d83abe MV |
587 | |
588 | (non-tail-recursive-factorial 500) | |
589 | @result{} | |
590 | 122013682599111006870123878542304692625357434@dots{} | |
591 | @end lisp | |
592 | ||
593 | If you prefer to try rewriting your code, you may be able to save stack | |
bfc083ec KR |
594 | space by making some of your procedures @dfn{tail recursive} |
595 | (@pxref{Tail Calls}). | |
07d83abe MV |
596 | |
597 | ||
598 | @node Examples of option use | |
599 | @subsubsection Examples of option use | |
600 | ||
601 | Here is an example of a session in which some read and debug option | |
602 | handling procedures are used. In this example, the user | |
603 | ||
604 | @enumerate | |
605 | @item | |
606 | Notices that the symbols @code{abc} and @code{aBc} are not the same | |
607 | @item | |
608 | Examines the @code{read-options}, and sees that @code{case-insensitive} | |
609 | is set to ``no''. | |
610 | @item | |
611 | Enables @code{case-insensitive} | |
612 | @item | |
613 | Verifies that now @code{aBc} and @code{abc} are the same | |
614 | @item | |
615 | Disables @code{case-insensitive} and enables debugging @code{backtrace} | |
616 | @item | |
617 | Reproduces the error of displaying @code{aBc} with backtracing enabled | |
618 | [FIXME: this last example is lame because there is no depth in the | |
619 | backtrace. Need to give a better example, possibly putting debugging | |
620 | option examples in a separate session.] | |
621 | @end enumerate | |
622 | ||
07d83abe MV |
623 | @smalllisp |
624 | guile> (define abc "hello") | |
625 | guile> abc | |
626 | "hello" | |
627 | guile> aBc | |
628 | ERROR: In expression aBc: | |
629 | ERROR: Unbound variable: aBc | |
630 | ABORT: (misc-error) | |
631 | ||
632 | Type "(backtrace)" to get more information. | |
633 | guile> (read-options 'help) | |
ef4cbc08 | 634 | keywords #f Style of keyword recognition: #f, 'prefix or 'postfix |
07d83abe MV |
635 | case-insensitive no Convert symbols to lower case. |
636 | positions yes Record positions of source code expressions. | |
637 | copy no Copy source code expressions. | |
638 | guile> (debug-options 'help) | |
639 | stack 20000 Stack size limit (0 = no check). | |
640 | debug yes Use the debugging evaluator. | |
641 | backtrace no Show backtrace on error. | |
642 | depth 20 Maximal length of printed backtrace. | |
643 | maxdepth 1000 Maximal number of stored backtrace frames. | |
644 | frames 3 Maximum number of tail-recursive frames in backtrace. | |
645 | indent 10 Maximal indentation in backtrace. | |
646 | backwards no Display backtrace in anti-chronological order. | |
647 | procnames yes Record procedure names at definition. | |
648 | trace no *Trace mode. | |
649 | breakpoints no *Check for breakpoints. | |
31e2cc50 | 650 | cheap yes *This option is now obsolete. Setting it has no effect. |
07d83abe MV |
651 | guile> (read-enable 'case-insensitive) |
652 | (keywords #f case-insensitive positions) | |
653 | guile> aBc | |
654 | "hello" | |
655 | guile> (read-disable 'case-insensitive) | |
656 | (keywords #f positions) | |
657 | guile> (debug-enable 'backtrace) | |
658 | (stack 20000 debug backtrace depth 20 maxdepth 1000 frames 3 indent 10 procnames cheap) | |
659 | guile> aBc | |
660 | ||
661 | Backtrace: | |
662 | 0* aBc | |
663 | ||
664 | ERROR: In expression aBc: | |
665 | ERROR: Unbound variable: aBc | |
666 | ABORT: (misc-error) | |
667 | guile> | |
668 | @end smalllisp | |
669 | ||
670 | ||
671 | @c Local Variables: | |
672 | @c TeX-master: "guile.texi" | |
673 | @c End: |