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1 | @page |
2 | @node SRFI Support | |
3 | @chapter SRFI Support Modules | |
8742c48b | 4 | @cindex SRFI |
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5 | |
6 | SRFI is an acronym for Scheme Request For Implementation. The SRFI | |
7 | documents define a lot of syntactic and procedure extensions to standard | |
8 | Scheme as defined in R5RS. | |
9 | ||
10 | Guile has support for a number of SRFIs. This chapter gives an overview | |
11 | over the available SRFIs and some usage hints. For complete | |
12 | documentation, design rationales and further examples, we advise you to | |
13 | get the relevant SRFI documents from the SRFI home page | |
14 | @url{http://srfi.schemers.org}. | |
15 | ||
16 | @menu | |
17 | * About SRFI Usage:: What to know about Guile's SRFI support. | |
18 | * SRFI-0:: cond-expand | |
19 | * SRFI-1:: List library. | |
20 | * SRFI-2:: and-let*. | |
21 | * SRFI-4:: Homogeneous numeric vector datatypes. | |
22 | * SRFI-6:: Basic String Ports. | |
23 | * SRFI-8:: receive. | |
24 | * SRFI-9:: define-record-type. | |
25 | * SRFI-10:: Hash-Comma Reader Extension. | |
26 | * SRFI-11:: let-values and let-values*. | |
27 | * SRFI-13:: String library. | |
28 | * SRFI-14:: Character-set library. | |
29 | * SRFI-16:: case-lambda | |
30 | * SRFI-17:: Generalized set! | |
bfc9c8e0 | 31 | * SRFI-19:: Time/Date library. |
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32 | @end menu |
33 | ||
34 | ||
35 | @node About SRFI Usage | |
36 | @section About SRFI Usage | |
37 | ||
38 | @c FIXME::martin: Review me! | |
39 | ||
40 | SRFI support in Guile is currently implemented partly in the core | |
41 | library, and partly as add-on modules. That means that some SRFIs are | |
42 | automatically available when the interpreter is started, whereas the | |
43 | other SRFIs require you to use the appropriate support module | |
12991fed | 44 | explicitly. |
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45 | |
46 | There are several reasons for this inconsistency. First, the feature | |
47 | checking syntactic form @code{cond-expand} (@pxref{SRFI-0}) must be | |
48 | available immediately, because it must be there when the user wants to | |
49 | check for the Scheme implementation, that is, before she can know that | |
50 | it is safe to use @code{use-modules} to load SRFI support modules. The | |
51 | second reason is that some features defined in SRFIs had been | |
52 | implemented in Guile before the developers started to add SRFI | |
53 | implementations as modules (for example SRFI-6 (@pxref{SRFI-6})). In | |
54 | the future, it is possible that SRFIs in the core library might be | |
55 | factored out into separate modules, requiring explicit module loading | |
56 | when they are needed. So you should be prepared to have to use | |
57 | @code{use-modules} someday in the future to access SRFI-6 bindings. If | |
58 | you want, you can do that already. We have included the module | |
59 | @code{(srfi srfi-6)} in the distribution, which currently does nothing, | |
60 | but ensures that you can write future-safe code. | |
61 | ||
62 | Generally, support for a specific SRFI is made available by using | |
63 | modules named @code{(srfi srfi-@var{number})}, where @var{number} is the | |
64 | number of the SRFI needed. Another possibility is to use the command | |
65 | line option @code{--use-srfi}, which will load the necessary modules | |
66 | automatically (@pxref{Invoking Guile}). | |
67 | ||
68 | ||
69 | @node SRFI-0 | |
70 | @section SRFI-0 - cond-expand | |
8742c48b | 71 | @cindex SRFI-0 |
7ea6af07 | 72 | @findex cond-expand |
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73 | |
74 | @c FIXME::martin: Review me! | |
75 | ||
76 | SRFI-0 defines a means for checking whether a Scheme implementation has | |
77 | support for a specified feature. The syntactic form @code{cond-expand}, | |
78 | which implements this means, has the following syntax. | |
79 | ||
80 | @example | |
81 | @group | |
82 | <cond-expand> | |
83 | --> (cond-expand <cond-expand-clause>+) | |
84 | | (cond-expand <cond-expand-clause>* (else <command-or-definition>)) | |
85 | <cond-expand-clause> | |
86 | --> (<feature-requirement> <command-or-definition>*) | |
87 | <feature-requirement> | |
88 | --> <feature-identifier> | |
89 | | (and <feature-requirement>*) | |
90 | | (or <feature-requirement>*) | |
91 | | (not <feature-requirement>) | |
92 | <feature-identifier> | |
93 | --> <a symbol which is the name or alias of a SRFI> | |
94 | @end group | |
95 | @end example | |
96 | ||
97 | When evaluated, this form checks all clauses in order, until it finds | |
98 | one whose feature requirement is satisfied. Then the form expands into | |
99 | the commands or definitions in the clause. A requirement is tested as | |
100 | follows: | |
101 | ||
102 | @itemize @bullet | |
103 | @item | |
104 | If it is a symbol, it is satisfied if the feature identifier is | |
105 | supported. | |
106 | ||
107 | @item | |
108 | If it is an @code{and} form, all requirements must be satisfied. If no | |
109 | requirements are given, it is satisfied, too. | |
110 | ||
111 | @item | |
112 | If it is an @code{or} form, at least one of the requirements must be | |
113 | satisfied. If no requirements are given, it is not satisfied. | |
114 | ||
115 | @item | |
116 | If it is a @code{not} form, the feature requirement must @emph{not} be | |
117 | satisfied. | |
118 | ||
119 | @item | |
120 | If the feature requirement is the keyword @code{else} and it is the last | |
121 | clause, it is satisfied if no prior clause matched. | |
122 | @end itemize | |
123 | ||
124 | If no clause is satisfied, an error is signalled. | |
125 | ||
126 | Since @code{cond-expand} is needed to tell what a Scheme implementation | |
127 | provides, it must be accessible without using any | |
85a9b4ed | 128 | implementation-dependent operations, such as @code{use-modules} in |
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129 | Guile. Thus, it is not necessary to use any module to get access to |
130 | this form. | |
131 | ||
132 | Currently, the feature identifiers @code{guile}, @code{r5rs} and | |
133 | @code{srfi-0} are supported. The other SRFIs are not in that list by | |
134 | default, because the SRFI modules must be explicitly used before their | |
12991fed | 135 | exported bindings can be used. |
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136 | |
137 | So if a Scheme program wishes to use SRFI-8, it has two possibilities: | |
138 | First, it can check whether the running Scheme implementation is Guile, | |
139 | and if it is, it can use the appropriate module: | |
140 | ||
141 | @lisp | |
142 | (cond-expand | |
143 | (guile | |
144 | (use-modules (srfi srfi-8))) | |
145 | (srfi-8 | |
146 | #t)) | |
147 | ;; otherwise fail. | |
148 | @end lisp | |
149 | ||
150 | The other possibility is to use the @code{--use-srfi} command line | |
151 | option when invoking Guile (@pxref{Invoking Guile}). When you do that, | |
152 | the specified SRFI support modules will be loaded and add their feature | |
153 | identifier to the list of symbols checked by @code{cond-expand}. | |
154 | ||
155 | So, if you invoke Guile like this: | |
156 | ||
157 | @example | |
158 | $ guile --use-srfi=8 | |
159 | @end example | |
160 | ||
161 | the following snippet will expand to @code{'hooray}. | |
162 | ||
163 | @lisp | |
164 | (cond-expand (srfi-8 'hooray)) | |
165 | @end lisp | |
166 | ||
167 | ||
168 | @node SRFI-1 | |
169 | @section SRFI-1 - List library | |
8742c48b | 170 | @cindex SRFI-1 |
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171 | |
172 | @c FIXME::martin: Review me! | |
173 | ||
174 | The list library defined in SRFI-1 contains a lot of useful list | |
175 | processing procedures for construction, examining, destructuring and | |
176 | manipulating lists and pairs. | |
177 | ||
178 | Since SRFI-1 also defines some procedures which are already contained | |
179 | in R5RS and thus are supported by the Guile core library, some list | |
180 | and pair procedures which appear in the SRFI-1 document may not appear | |
181 | in this section. So when looking for a particular list/pair | |
182 | processing procedure, you should also have a look at the sections | |
183 | @ref{Lists} and @ref{Pairs}. | |
184 | ||
185 | @menu | |
186 | * SRFI-1 Constructors:: Constructing new lists. | |
187 | * SRFI-1 Predicates:: Testing list for specific properties. | |
188 | * SRFI-1 Selectors:: Selecting elements from lists. | |
189 | * SRFI-1 Length Append etc:: Length calculation and list appending. | |
190 | * SRFI-1 Fold and Map:: Higher-order list processing. | |
191 | * SRFI-1 Filtering and Partitioning:: Filter lists based on predicates. | |
85a9b4ed | 192 | * SRFI-1 Searching:: Search for elements. |
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193 | * SRFI-1 Deleting:: Delete elements from lists. |
194 | * SRFI-1 Association Lists:: Handle association lists. | |
195 | * SRFI-1 Set Operations:: Use lists for representing sets. | |
196 | @end menu | |
197 | ||
198 | @node SRFI-1 Constructors | |
199 | @subsection Constructors | |
200 | ||
201 | @c FIXME::martin: Review me! | |
202 | ||
203 | New lists can be constructed by calling one of the following | |
204 | procedures. | |
205 | ||
8f85c0c6 | 206 | @deffn {Scheme Procedure} xcons d a |
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207 | Like @code{cons}, but with interchanged arguments. Useful mostly when |
208 | passed to higher-order procedures. | |
209 | @end deffn | |
210 | ||
8f85c0c6 | 211 | @deffn {Scheme Procedure} list-tabulate n init-proc |
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212 | Return an @var{n}-element list, where each list element is produced by |
213 | applying the procedure @var{init-proc} to the corresponding list | |
214 | index. The order in which @var{init-proc} is applied to the indices | |
215 | is not specified. | |
216 | @end deffn | |
217 | ||
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218 | @deffn {Scheme Procedure} list-copy lst |
219 | Return a new list containing the elements of the list @var{lst}. | |
220 | ||
221 | This function differs from the core @code{list-copy} (@pxref{List | |
222 | Constructors}) in accepting improper lists too. And if @var{lst} is | |
223 | not a pair at all then it's treated as the final tail of an improper | |
224 | list and simply returned. | |
225 | @end deffn | |
226 | ||
8f85c0c6 | 227 | @deffn {Scheme Procedure} circular-list elt1 elt2 @dots{} |
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228 | Return a circular list containing the given arguments @var{elt1} |
229 | @var{elt2} @dots{}. | |
230 | @end deffn | |
231 | ||
8f85c0c6 | 232 | @deffn {Scheme Procedure} iota count [start step] |
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233 | Return a list containing @var{count} numbers, starting from |
234 | @var{start} and adding @var{step} each time. The default @var{start} | |
235 | is 0, the default @var{step} is 1. For example, | |
a0e07ba4 | 236 | |
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237 | @example |
238 | (iota 6) @result{} (0 1 2 3 4 5) | |
239 | (iota 4 2.5 -2) @result{} (2.5 0.5 -1.5 -3.5) | |
240 | @end example | |
a0e07ba4 | 241 | |
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242 | This function takes its name from the corresponding primitive in the |
243 | APL language. | |
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244 | @end deffn |
245 | ||
246 | ||
247 | @node SRFI-1 Predicates | |
248 | @subsection Predicates | |
249 | ||
250 | @c FIXME::martin: Review me! | |
251 | ||
252 | The procedures in this section test specific properties of lists. | |
253 | ||
8f85c0c6 | 254 | @deffn {Scheme Procedure} proper-list? obj |
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255 | Return @code{#t} if @var{obj} is a proper list, that is a finite list, |
256 | terminated with the empty list. Otherwise, return @code{#f}. | |
257 | @end deffn | |
258 | ||
8f85c0c6 | 259 | @deffn {Scheme Procedure} circular-list? obj |
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260 | Return @code{#t} if @var{obj} is a circular list, otherwise return |
261 | @code{#f}. | |
262 | @end deffn | |
263 | ||
8f85c0c6 | 264 | @deffn {Scheme Procedure} dotted-list? obj |
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265 | Return @code{#t} if @var{obj} is a dotted list, return @code{#f} |
266 | otherwise. A dotted list is a finite list which is not terminated by | |
267 | the empty list, but some other value. | |
268 | @end deffn | |
269 | ||
8f85c0c6 | 270 | @deffn {Scheme Procedure} null-list? lst |
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271 | Return @code{#t} if @var{lst} is the empty list @code{()}, @code{#f} |
272 | otherwise. If something else than a proper or circular list is passed | |
85a9b4ed | 273 | as @var{lst}, an error is signalled. This procedure is recommended |
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274 | for checking for the end of a list in contexts where dotted lists are |
275 | not allowed. | |
276 | @end deffn | |
277 | ||
8f85c0c6 | 278 | @deffn {Scheme Procedure} not-pair? obj |
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279 | Return @code{#t} is @var{obj} is not a pair, @code{#f} otherwise. |
280 | This is shorthand notation @code{(not (pair? @var{obj}))} and is | |
281 | supposed to be used for end-of-list checking in contexts where dotted | |
282 | lists are allowed. | |
283 | @end deffn | |
284 | ||
8f85c0c6 | 285 | @deffn {Scheme Procedure} list= elt= list1 @dots{} |
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286 | Return @code{#t} if all argument lists are equal, @code{#f} otherwise. |
287 | List equality is determined by testing whether all lists have the same | |
288 | length and the corresponding elements are equal in the sense of the | |
289 | equality predicate @var{elt=}. If no or only one list is given, | |
290 | @code{#t} is returned. | |
291 | @end deffn | |
292 | ||
293 | ||
294 | @node SRFI-1 Selectors | |
295 | @subsection Selectors | |
296 | ||
297 | @c FIXME::martin: Review me! | |
298 | ||
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299 | @deffn {Scheme Procedure} first pair |
300 | @deffnx {Scheme Procedure} second pair | |
301 | @deffnx {Scheme Procedure} third pair | |
302 | @deffnx {Scheme Procedure} fourth pair | |
303 | @deffnx {Scheme Procedure} fifth pair | |
304 | @deffnx {Scheme Procedure} sixth pair | |
305 | @deffnx {Scheme Procedure} seventh pair | |
306 | @deffnx {Scheme Procedure} eighth pair | |
307 | @deffnx {Scheme Procedure} ninth pair | |
308 | @deffnx {Scheme Procedure} tenth pair | |
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309 | These are synonyms for @code{car}, @code{cadr}, @code{caddr}, @dots{}. |
310 | @end deffn | |
311 | ||
8f85c0c6 | 312 | @deffn {Scheme Procedure} car+cdr pair |
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313 | Return two values, the @sc{car} and the @sc{cdr} of @var{pair}. |
314 | @end deffn | |
315 | ||
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316 | @deffn {Scheme Procedure} take lst i |
317 | @deffnx {Scheme Procedure} take! lst i | |
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318 | Return a list containing the first @var{i} elements of @var{lst}. |
319 | ||
320 | @code{take!} may modify the structure of the argument list @var{lst} | |
321 | in order to produce the result. | |
322 | @end deffn | |
323 | ||
8f85c0c6 | 324 | @deffn {Scheme Procedure} drop lst i |
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325 | Return a list containing all but the first @var{i} elements of |
326 | @var{lst}. | |
327 | @end deffn | |
328 | ||
8f85c0c6 | 329 | @deffn {Scheme Procedure} take-right lst i |
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330 | Return the a list containing the @var{i} last elements of @var{lst}. |
331 | @end deffn | |
332 | ||
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333 | @deffn {Scheme Procedure} drop-right lst i |
334 | @deffnx {Scheme Procedure} drop-right! lst i | |
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335 | Return the a list containing all but the @var{i} last elements of |
336 | @var{lst}. | |
337 | ||
338 | @code{drop-right!} may modify the structure of the argument list | |
339 | @var{lst} in order to produce the result. | |
340 | @end deffn | |
341 | ||
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342 | @deffn {Scheme Procedure} split-at lst i |
343 | @deffnx {Scheme Procedure} split-at! lst i | |
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344 | Return two values, a list containing the first @var{i} elements of the |
345 | list @var{lst} and a list containing the remaining elements. | |
346 | ||
347 | @code{split-at!} may modify the structure of the argument list | |
348 | @var{lst} in order to produce the result. | |
349 | @end deffn | |
350 | ||
8f85c0c6 | 351 | @deffn {Scheme Procedure} last lst |
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352 | Return the last element of the non-empty, finite list @var{lst}. |
353 | @end deffn | |
354 | ||
355 | ||
356 | @node SRFI-1 Length Append etc | |
357 | @subsection Length, Append, Concatenate, etc. | |
358 | ||
359 | @c FIXME::martin: Review me! | |
360 | ||
8f85c0c6 | 361 | @deffn {Scheme Procedure} length+ lst |
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362 | Return the length of the argument list @var{lst}. When @var{lst} is a |
363 | circular list, @code{#f} is returned. | |
364 | @end deffn | |
365 | ||
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366 | @deffn {Scheme Procedure} concatenate list-of-lists |
367 | @deffnx {Scheme Procedure} concatenate! list-of-lists | |
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368 | Construct a list by appending all lists in @var{list-of-lists}. |
369 | ||
370 | @code{concatenate!} may modify the structure of the given lists in | |
371 | order to produce the result. | |
372 | @end deffn | |
373 | ||
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374 | @deffn {Scheme Procedure} append-reverse rev-head tail |
375 | @deffnx {Scheme Procedure} append-reverse! rev-head tail | |
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376 | Reverse @var{rev-head}, append @var{tail} and return the result. This |
377 | is equivalent to @code{(append (reverse @var{rev-head}) @var{tail})}, | |
378 | but more efficient. | |
379 | ||
380 | @code{append-reverse!} may modify @var{rev-head} in order to produce | |
381 | the result. | |
382 | @end deffn | |
383 | ||
8f85c0c6 | 384 | @deffn {Scheme Procedure} zip lst1 lst2 @dots{} |
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385 | Return a list as long as the shortest of the argument lists, where |
386 | each element is a list. The first list contains the first elements of | |
387 | the argument lists, the second list contains the second elements, and | |
388 | so on. | |
389 | @end deffn | |
390 | ||
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391 | @deffn {Scheme Procedure} unzip1 lst |
392 | @deffnx {Scheme Procedure} unzip2 lst | |
393 | @deffnx {Scheme Procedure} unzip3 lst | |
394 | @deffnx {Scheme Procedure} unzip4 lst | |
395 | @deffnx {Scheme Procedure} unzip5 lst | |
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396 | @code{unzip1} takes a list of lists, and returns a list containing the |
397 | first elements of each list, @code{unzip2} returns two lists, the | |
398 | first containing the first elements of each lists and the second | |
399 | containing the second elements of each lists, and so on. | |
400 | @end deffn | |
401 | ||
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402 | @deffn {Scheme Procedure} count pred lst1 @dots{} lstN |
403 | Return a count of the number of times @var{pred} returns true when | |
404 | called on elements from the given lists. | |
405 | ||
406 | @var{pred} is called with @var{N} parameters @code{(@var{pred} | |
407 | @var{elem1} @dots{} @var{elemN})}, each element being from the | |
408 | corresponding @var{lst1} @dots{} @var{lstN}. The first call is with | |
409 | the first element of each list, the second with the second element | |
410 | from each, and so on. | |
411 | ||
412 | Counting stops when the end of the shortest list is reached. At least | |
413 | one list must be non-circular. | |
414 | @end deffn | |
415 | ||
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416 | |
417 | @node SRFI-1 Fold and Map | |
418 | @subsection Fold, Unfold & Map | |
419 | ||
420 | @c FIXME::martin: Review me! | |
421 | ||
8f85c0c6 | 422 | @deffn {Scheme Procedure} fold kons knil lst1 lst2 @dots{} |
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423 | Fold the procedure @var{kons} across all elements of @var{lst1}, |
424 | @var{lst2}, @dots{}. Produce the result of | |
425 | ||
426 | @code{(@var{kons} @var{en1} @var{en2} @dots{} (@var{kons} @var{e21} | |
427 | @var{e22} (@var{kons} @var{e11} @var{e12} @var{knil})))}, | |
428 | ||
429 | if @var{enm} are the elements of the lists @var{lst1}, @var{lst2}, | |
430 | @dots{}. | |
431 | @end deffn | |
432 | ||
8f85c0c6 | 433 | @deffn {Scheme Procedure} fold-right kons knil lst1 lst2 @dots{} |
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434 | Similar to @code{fold}, but applies @var{kons} in right-to-left order |
435 | to the list elements, that is: | |
436 | ||
437 | @code{(@var{kons} @var{e11} @var{e12}(@var{kons} @var{e21} | |
438 | @var{e22} @dots{} (@var{kons} @var{en1} @var{en2} @var{knil})))}, | |
439 | @end deffn | |
440 | ||
8f85c0c6 | 441 | @deffn {Scheme Procedure} pair-fold kons knil lst1 lst2 @dots{} |
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442 | Like @code{fold}, but apply @var{kons} to the pairs of the list |
443 | instead of the list elements. | |
444 | @end deffn | |
445 | ||
8f85c0c6 | 446 | @deffn {Scheme Procedure} pair-fold-right kons knil lst1 lst2 @dots{} |
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447 | Like @code{fold-right}, but apply @var{kons} to the pairs of the list |
448 | instead of the list elements. | |
449 | @end deffn | |
450 | ||
8f85c0c6 | 451 | @deffn {Scheme Procedure} reduce f ridentity lst |
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452 | @code{reduce} is a variant of @code{fold}. If @var{lst} is |
453 | @code{()}, @var{ridentity} is returned. Otherwise, @code{(fold f (car | |
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454 | @var{lst}) (cdr @var{lst}))} is returned. |
455 | @end deffn | |
456 | ||
8f85c0c6 | 457 | @deffn {Scheme Procedure} reduce-right f ridentity lst |
b5aa0215 | 458 | This is the @code{fold-right} variant of @code{reduce}. |
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459 | @end deffn |
460 | ||
8f85c0c6 | 461 | @deffn {Scheme Procedure} unfold p f g seed [tail-gen] |
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462 | @code{unfold} is defined as follows: |
463 | ||
464 | @lisp | |
465 | (unfold p f g seed) = | |
466 | (if (p seed) (tail-gen seed) | |
467 | (cons (f seed) | |
468 | (unfold p f g (g seed)))) | |
469 | @end lisp | |
470 | ||
471 | @table @var | |
472 | @item p | |
473 | Determines when to stop unfolding. | |
474 | ||
475 | @item f | |
476 | Maps each seed value to the corresponding list element. | |
477 | ||
478 | @item g | |
479 | Maps each seed value to next seed valu. | |
480 | ||
481 | @item seed | |
482 | The state value for the unfold. | |
483 | ||
484 | @item tail-gen | |
485 | Creates the tail of the list; defaults to @code{(lambda (x) '())}. | |
486 | @end table | |
487 | ||
488 | @var{g} produces a series of seed values, which are mapped to list | |
489 | elements by @var{f}. These elements are put into a list in | |
490 | left-to-right order, and @var{p} tells when to stop unfolding. | |
491 | @end deffn | |
492 | ||
8f85c0c6 | 493 | @deffn {Scheme Procedure} unfold-right p f g seed [tail] |
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494 | Construct a list with the following loop. |
495 | ||
496 | @lisp | |
497 | (let lp ((seed seed) (lis tail)) | |
498 | (if (p seed) lis | |
499 | (lp (g seed) | |
500 | (cons (f seed) lis)))) | |
501 | @end lisp | |
502 | ||
503 | @table @var | |
504 | @item p | |
505 | Determines when to stop unfolding. | |
506 | ||
507 | @item f | |
508 | Maps each seed value to the corresponding list element. | |
509 | ||
510 | @item g | |
511 | Maps each seed value to next seed valu. | |
512 | ||
513 | @item seed | |
514 | The state value for the unfold. | |
515 | ||
516 | @item tail-gen | |
517 | Creates the tail of the list; defaults to @code{(lambda (x) '())}. | |
518 | @end table | |
519 | ||
520 | @end deffn | |
521 | ||
8f85c0c6 | 522 | @deffn {Scheme Procedure} map f lst1 lst2 @dots{} |
a0e07ba4 NJ |
523 | Map the procedure over the list(s) @var{lst1}, @var{lst2}, @dots{} and |
524 | return a list containing the results of the procedure applications. | |
525 | This procedure is extended with respect to R5RS, because the argument | |
526 | lists may have different lengths. The result list will have the same | |
527 | length as the shortest argument lists. The order in which @var{f} | |
528 | will be applied to the list element(s) is not specified. | |
529 | @end deffn | |
530 | ||
8f85c0c6 | 531 | @deffn {Scheme Procedure} for-each f lst1 lst2 @dots{} |
a0e07ba4 NJ |
532 | Apply the procedure @var{f} to each pair of corresponding elements of |
533 | the list(s) @var{lst1}, @var{lst2}, @dots{}. The return value is not | |
534 | specified. This procedure is extended with respect to R5RS, because | |
535 | the argument lists may have different lengths. The shortest argument | |
536 | list determines the number of times @var{f} is called. @var{f} will | |
85a9b4ed | 537 | be applied to the list elements in left-to-right order. |
a0e07ba4 NJ |
538 | |
539 | @end deffn | |
540 | ||
8f85c0c6 NJ |
541 | @deffn {Scheme Procedure} append-map f lst1 lst2 @dots{} |
542 | @deffnx {Scheme Procedure} append-map! f lst1 lst2 @dots{} | |
12991fed | 543 | Equivalent to |
a0e07ba4 NJ |
544 | |
545 | @lisp | |
12991fed | 546 | (apply append (map f clist1 clist2 ...)) |
a0e07ba4 NJ |
547 | @end lisp |
548 | ||
12991fed | 549 | and |
a0e07ba4 NJ |
550 | |
551 | @lisp | |
12991fed | 552 | (apply append! (map f clist1 clist2 ...)) |
a0e07ba4 NJ |
553 | @end lisp |
554 | ||
555 | Map @var{f} over the elements of the lists, just as in the @code{map} | |
556 | function. However, the results of the applications are appended | |
557 | together to make the final result. @code{append-map} uses | |
558 | @code{append} to append the results together; @code{append-map!} uses | |
559 | @code{append!}. | |
560 | ||
561 | The dynamic order in which the various applications of @var{f} are | |
562 | made is not specified. | |
563 | @end deffn | |
564 | ||
8f85c0c6 | 565 | @deffn {Scheme Procedure} map! f lst1 lst2 @dots{} |
a0e07ba4 NJ |
566 | Linear-update variant of @code{map} -- @code{map!} is allowed, but not |
567 | required, to alter the cons cells of @var{lst1} to construct the | |
568 | result list. | |
569 | ||
570 | The dynamic order in which the various applications of @var{f} are | |
571 | made is not specified. In the n-ary case, @var{lst2}, @var{lst3}, | |
572 | @dots{} must have at least as many elements as @var{lst1}. | |
573 | @end deffn | |
574 | ||
8f85c0c6 | 575 | @deffn {Scheme Procedure} pair-for-each f lst1 lst2 @dots{} |
a0e07ba4 NJ |
576 | Like @code{for-each}, but applies the procedure @var{f} to the pairs |
577 | from which the argument lists are constructed, instead of the list | |
578 | elements. The return value is not specified. | |
579 | @end deffn | |
580 | ||
8f85c0c6 | 581 | @deffn {Scheme Procedure} filter-map f lst1 lst2 @dots{} |
a0e07ba4 NJ |
582 | Like @code{map}, but only results from the applications of @var{f} |
583 | which are true are saved in the result list. | |
584 | @end deffn | |
585 | ||
586 | ||
587 | @node SRFI-1 Filtering and Partitioning | |
588 | @subsection Filtering and Partitioning | |
589 | ||
590 | @c FIXME::martin: Review me! | |
591 | ||
592 | Filtering means to collect all elements from a list which satisfy a | |
593 | specific condition. Partitioning a list means to make two groups of | |
594 | list elements, one which contains the elements satisfying a condition, | |
595 | and the other for the elements which don't. | |
596 | ||
60e25dc4 KR |
597 | The @code{filter} and @code{filter!} functions are implemented in the |
598 | Guile core, @xref{List Modification}. | |
a0e07ba4 | 599 | |
8f85c0c6 NJ |
600 | @deffn {Scheme Procedure} partition pred lst |
601 | @deffnx {Scheme Procedure} partition! pred lst | |
193239f1 KR |
602 | Split @var{lst} into those elements which do and don't satisfy the |
603 | predicate @var{pred}. | |
a0e07ba4 | 604 | |
193239f1 KR |
605 | The return is two values (@pxref{Multiple Values}), the first being a |
606 | list of all elements from @var{lst} which satisfy @var{pred}, the | |
607 | second a list of those which do not. | |
608 | ||
609 | The elements in the result lists are in the same order as in @var{lst} | |
610 | but the order in which the calls @code{(@var{pred} elem)} are made on | |
611 | the list elements is unspecified. | |
612 | ||
613 | @code{partition} does not change @var{lst}, but one of the returned | |
614 | lists may share a tail with it. @code{partition!} may modify | |
615 | @var{lst} to construct its return. | |
a0e07ba4 NJ |
616 | @end deffn |
617 | ||
8f85c0c6 NJ |
618 | @deffn {Scheme Procedure} remove pred lst |
619 | @deffnx {Scheme Procedure} remove! pred lst | |
a0e07ba4 NJ |
620 | Return a list containing all elements from @var{lst} which do not |
621 | satisfy the predicate @var{pred}. The elements in the result list | |
622 | have the same order as in @var{lst}. The order in which @var{pred} is | |
623 | applied to the list elements is not specified. | |
624 | ||
625 | @code{remove!} is allowed, but not required to modify the structure of | |
626 | the input list. | |
627 | @end deffn | |
628 | ||
629 | ||
630 | @node SRFI-1 Searching | |
631 | @subsection Searching | |
632 | ||
633 | @c FIXME::martin: Review me! | |
634 | ||
635 | The procedures for searching elements in lists either accept a | |
636 | predicate or a comparison object for determining which elements are to | |
637 | be searched. | |
638 | ||
8f85c0c6 | 639 | @deffn {Scheme Procedure} find pred lst |
a0e07ba4 NJ |
640 | Return the first element of @var{lst} which satisfies the predicate |
641 | @var{pred} and @code{#f} if no such element is found. | |
642 | @end deffn | |
643 | ||
8f85c0c6 | 644 | @deffn {Scheme Procedure} find-tail pred lst |
a0e07ba4 NJ |
645 | Return the first pair of @var{lst} whose @sc{car} satisfies the |
646 | predicate @var{pred} and @code{#f} if no such element is found. | |
647 | @end deffn | |
648 | ||
8f85c0c6 NJ |
649 | @deffn {Scheme Procedure} take-while pred lst |
650 | @deffnx {Scheme Procedure} take-while! pred lst | |
a0e07ba4 NJ |
651 | Return the longest initial prefix of @var{lst} whose elements all |
652 | satisfy the predicate @var{pred}. | |
653 | ||
654 | @code{take-while!} is allowed, but not required to modify the input | |
655 | list while producing the result. | |
656 | @end deffn | |
657 | ||
8f85c0c6 | 658 | @deffn {Scheme Procedure} drop-while pred lst |
a0e07ba4 NJ |
659 | Drop the longest initial prefix of @var{lst} whose elements all |
660 | satisfy the predicate @var{pred}. | |
661 | @end deffn | |
662 | ||
8f85c0c6 NJ |
663 | @deffn {Scheme Procedure} span pred lst |
664 | @deffnx {Scheme Procedure} span! pred lst | |
665 | @deffnx {Scheme Procedure} break pred lst | |
666 | @deffnx {Scheme Procedure} break! pred lst | |
a0e07ba4 NJ |
667 | @code{span} splits the list @var{lst} into the longest initial prefix |
668 | whose elements all satisfy the predicate @var{pred}, and the remaining | |
669 | tail. @code{break} inverts the sense of the predicate. | |
670 | ||
671 | @code{span!} and @code{break!} are allowed, but not required to modify | |
672 | the structure of the input list @var{lst} in order to produce the | |
673 | result. | |
3e73b6f9 KR |
674 | |
675 | Note that the name @code{break} conflicts with the @code{break} | |
676 | binding established by @code{while} (@pxref{while do}). Applications | |
677 | wanting to use @code{break} from within a @code{while} loop will need | |
678 | to make a new define under a different name. | |
a0e07ba4 NJ |
679 | @end deffn |
680 | ||
8f85c0c6 | 681 | @deffn {Scheme Procedure} any pred lst1 lst2 @dots{} |
a0e07ba4 NJ |
682 | Apply @var{pred} across the lists and return a true value if the |
683 | predicate returns true for any of the list elements(s); return | |
684 | @code{#f} otherwise. The true value returned is always the result of | |
85a9b4ed | 685 | the first successful application of @var{pred}. |
a0e07ba4 NJ |
686 | @end deffn |
687 | ||
8f85c0c6 | 688 | @deffn {Scheme Procedure} every pred lst1 lst2 @dots{} |
a0e07ba4 NJ |
689 | Apply @var{pred} across the lists and return a true value if the |
690 | predicate returns true for every of the list elements(s); return | |
691 | @code{#f} otherwise. The true value returned is always the result of | |
85a9b4ed | 692 | the final successful application of @var{pred}. |
a0e07ba4 NJ |
693 | @end deffn |
694 | ||
8f85c0c6 | 695 | @deffn {Scheme Procedure} list-index pred lst1 lst2 @dots{} |
a0e07ba4 NJ |
696 | Return the index of the leftmost element that satisfies @var{pred}. |
697 | @end deffn | |
698 | ||
8f85c0c6 | 699 | @deffn {Scheme Procedure} member x lst [=] |
a0e07ba4 NJ |
700 | Return the first sublist of @var{lst} whose @sc{car} is equal to |
701 | @var{x}. If @var{x} does no appear in @var{lst}, return @code{#f}. | |
702 | Equality is determined by the equality predicate @var{=}, or | |
703 | @code{equal?} if @var{=} is not given. | |
ea6ea01b KR |
704 | |
705 | This function extends the core @code{member} by accepting an equality | |
706 | predicate. (@pxref{List Searching}) | |
a0e07ba4 NJ |
707 | @end deffn |
708 | ||
709 | ||
710 | @node SRFI-1 Deleting | |
711 | @subsection Deleting | |
712 | ||
713 | @c FIXME::martin: Review me! | |
714 | ||
8f85c0c6 NJ |
715 | @deffn {Scheme Procedure} delete x lst [=] |
716 | @deffnx {Scheme Procedure} delete! x lst [=] | |
b6b9376a KR |
717 | Return a list containing the elements of @var{lst} but with those |
718 | equal to @var{x} deleted. The returned elements will be in the same | |
719 | order as they were in @var{lst}. | |
720 | ||
721 | Equality is determined by the @var{=} predicate, or @code{equal?} if | |
722 | not given. An equality call is made just once for each element, but | |
723 | the order in which the calls are made on the elements is unspecified. | |
a0e07ba4 | 724 | |
243bdb63 | 725 | The equality calls are always @code{(= x elem)}, ie.@: the given @var{x} |
b6b9376a KR |
726 | is first. This means for instance elements greater than 5 can be |
727 | deleted with @code{(delete 5 lst <)}. | |
728 | ||
729 | @code{delete} does not modify @var{lst}, but the return might share a | |
730 | common tail with @var{lst}. @code{delete!} may modify the structure | |
731 | of @var{lst} to construct its return. | |
ea6ea01b KR |
732 | |
733 | These functions extend the core @code{delete} and @code{delete!} in | |
734 | accepting an equality predicate. (@pxref{List Modification}) | |
a0e07ba4 NJ |
735 | @end deffn |
736 | ||
8f85c0c6 NJ |
737 | @deffn {Scheme Procedure} delete-duplicates lst [=] |
738 | @deffnx {Scheme Procedure} delete-duplicates! lst [=] | |
b6b9376a KR |
739 | Return a list containing the elements of @var{lst} but without |
740 | duplicates. | |
741 | ||
742 | When elements are equal, only the first in @var{lst} is retained. | |
743 | Equal elements can be anywhere in @var{lst}, they don't have to be | |
744 | adjacent. The returned list will have the retained elements in the | |
745 | same order as they were in @var{lst}. | |
746 | ||
747 | Equality is determined by the @var{=} predicate, or @code{equal?} if | |
748 | not given. Calls @code{(= x y)} are made with element @var{x} being | |
749 | before @var{y} in @var{lst}. A call is made at most once for each | |
750 | combination, but the sequence of the calls across the elements is | |
751 | unspecified. | |
752 | ||
753 | @code{delete-duplicates} does not modify @var{lst}, but the return | |
754 | might share a common tail with @var{lst}. @code{delete-duplicates!} | |
755 | may modify the structure of @var{lst} to construct its return. | |
756 | ||
757 | In the worst case, this is an @math{O(N^2)} algorithm because it must | |
758 | check each element against all those preceding it. For long lists it | |
759 | is more efficient to sort and then compare only adjacent elements. | |
a0e07ba4 NJ |
760 | @end deffn |
761 | ||
762 | ||
763 | @node SRFI-1 Association Lists | |
764 | @subsection Association Lists | |
765 | ||
766 | @c FIXME::martin: Review me! | |
767 | ||
768 | Association lists are described in detail in section @ref{Association | |
769 | Lists}. The present section only documents the additional procedures | |
770 | for dealing with association lists defined by SRFI-1. | |
771 | ||
8f85c0c6 | 772 | @deffn {Scheme Procedure} assoc key alist [=] |
a0e07ba4 NJ |
773 | Return the pair from @var{alist} which matches @var{key}. Equality is |
774 | determined by @var{=}, which defaults to @code{equal?} if not given. | |
775 | @var{alist} must be an association lists---a list of pairs. | |
ea6ea01b KR |
776 | |
777 | This function extends the core @code{assoc} by accepting an equality | |
778 | predicate. (@pxref{Association Lists}) | |
a0e07ba4 NJ |
779 | @end deffn |
780 | ||
8f85c0c6 | 781 | @deffn {Scheme Procedure} alist-cons key datum alist |
a0e07ba4 NJ |
782 | Equivalent to |
783 | ||
784 | @lisp | |
785 | (cons (cons @var{key} @var{datum}) @var{alist}) | |
786 | @end lisp | |
787 | ||
788 | This procedure is used to coons a new pair onto an existing | |
789 | association list. | |
790 | @end deffn | |
791 | ||
8f85c0c6 | 792 | @deffn {Scheme Procedure} alist-copy alist |
a0e07ba4 NJ |
793 | Return a newly allocated copy of @var{alist}, that means that the |
794 | spine of the list as well as the pairs are copied. | |
795 | @end deffn | |
796 | ||
8f85c0c6 NJ |
797 | @deffn {Scheme Procedure} alist-delete key alist [=] |
798 | @deffnx {Scheme Procedure} alist-delete! key alist [=] | |
bd35f1f0 KR |
799 | Return a list containing the elements of @var{alist} but with those |
800 | elements whose keys are equal to @var{key} deleted. The returned | |
801 | elements will be in the same order as they were in @var{alist}. | |
a0e07ba4 | 802 | |
bd35f1f0 KR |
803 | Equality is determined by the @var{=} predicate, or @code{equal?} if |
804 | not given. The order in which elements are tested is unspecified, but | |
805 | each equality call is made @code{(= key alistkey)}, ie. the given | |
806 | @var{key} parameter is first and the key from @var{alist} second. | |
807 | This means for instance all associations with a key greater than 5 can | |
808 | be removed with @code{(alist-delete 5 alist <)}. | |
809 | ||
810 | @code{alist-delete} does not modify @var{alist}, but the return might | |
811 | share a common tail with @var{alist}. @code{alist-delete!} may modify | |
812 | the list structure of @var{alist} to construct its return. | |
a0e07ba4 NJ |
813 | @end deffn |
814 | ||
815 | ||
816 | @node SRFI-1 Set Operations | |
817 | @subsection Set Operations on Lists | |
818 | ||
819 | @c FIXME::martin: Review me! | |
820 | ||
821 | Lists can be used for representing sets of objects. The procedures | |
822 | documented in this section can be used for such set representations. | |
85a9b4ed | 823 | Man combining several sets or adding elements, they make sure that no |
a0e07ba4 NJ |
824 | object is contained more than once in a given list. Please note that |
825 | lists are not a too efficient implementation method for sets, so if | |
826 | you need high performance, you should think about implementing a | |
827 | custom data structure for representing sets, such as trees, bitsets, | |
828 | hash tables or something similar. | |
829 | ||
830 | All these procedures accept an equality predicate as the first | |
831 | argument. This predicate is used for testing the objects in the list | |
832 | sets for sameness. | |
833 | ||
8f85c0c6 | 834 | @deffn {Scheme Procedure} lset<= = list1 @dots{} |
a0e07ba4 NJ |
835 | Return @code{#t} if every @var{listi} is a subset of @var{listi+1}, |
836 | otherwise return @code{#f}. Returns @code{#t} if called with less | |
837 | than two arguments. @var{=} is used for testing element equality. | |
838 | @end deffn | |
839 | ||
8f85c0c6 | 840 | @deffn {Scheme Procedure} lset= = list1 list2 @dots{} |
a0e07ba4 NJ |
841 | Return @code{#t} if all argument lists are equal. @var{=} is used for |
842 | testing element equality. | |
843 | @end deffn | |
844 | ||
8f85c0c6 NJ |
845 | @deffn {Scheme Procedure} lset-adjoin = list elt1 @dots{} |
846 | @deffnx {Scheme Procedure} lset-adjoin! = list elt1 @dots{} | |
a0e07ba4 NJ |
847 | Add all @var{elts} to the list @var{list}, suppressing duplicates and |
848 | return the resulting list. @code{lset-adjoin!} is allowed, but not | |
849 | required to modify its first argument. @var{=} is used for testing | |
850 | element equality. | |
851 | @end deffn | |
852 | ||
8f85c0c6 NJ |
853 | @deffn {Scheme Procedure} lset-union = list1 @dots{} |
854 | @deffnx {Scheme Procedure} lset-union! = list1 @dots{} | |
a0e07ba4 NJ |
855 | Return the union of all argument list sets. The union is the set of |
856 | all elements which appear in any of the argument sets. | |
857 | @code{lset-union!} is allowed, but not required to modify its first | |
858 | argument. @var{=} is used for testing element equality. | |
859 | @end deffn | |
860 | ||
8f85c0c6 NJ |
861 | @deffn {Scheme Procedure} lset-intersection = list1 list2 @dots{} |
862 | @deffnx {Scheme Procedure} lset-intersection! = list1 list2 @dots{} | |
a0e07ba4 NJ |
863 | Return the intersection of all argument list sets. The intersection |
864 | is the set containing all elements which appear in all argument sets. | |
865 | @code{lset-intersection!} is allowed, but not required to modify its | |
866 | first argument. @var{=} is used for testing element equality. | |
867 | @end deffn | |
868 | ||
8f85c0c6 NJ |
869 | @deffn {Scheme Procedure} lset-difference = list1 list2 @dots{} |
870 | @deffnx {Scheme Procedure} lset-difference! = list1 list2 @dots{} | |
a0e07ba4 NJ |
871 | Return the difference of all argument list sets. The difference is |
872 | the the set containing all elements of the first list which do not | |
873 | appear in the other lists. @code{lset-difference!} is allowed, but | |
874 | not required to modify its first argument. @var{=} is used for testing | |
875 | element equality. | |
876 | @end deffn | |
877 | ||
8f85c0c6 NJ |
878 | @deffn {Scheme Procedure} lset-xor = list1 @dots{} |
879 | @deffnx {Scheme Procedure} lset-xor! = list1 @dots{} | |
a0e07ba4 NJ |
880 | Return the set containing all elements which appear in the first |
881 | argument list set, but not in the second; or, more generally: which | |
882 | appear in an odd number of sets. @code{lset-xor!} is allowed, but | |
883 | not required to modify its first argument. @var{=} is used for testing | |
884 | element equality. | |
885 | @end deffn | |
886 | ||
8f85c0c6 NJ |
887 | @deffn {Scheme Procedure} lset-diff+intersection = list1 list2 @dots{} |
888 | @deffnx {Scheme Procedure} lset-diff+intersection! = list1 list2 @dots{} | |
a0e07ba4 NJ |
889 | Return two values, the difference and the intersection of the argument |
890 | list sets. This works like a combination of @code{lset-difference} and | |
891 | @code{lset-intersection}, but is more efficient. | |
892 | @code{lset-diff+intersection!} is allowed, but not required to modify | |
893 | its first argument. @var{=} is used for testing element equality. You | |
894 | have to use some means to deal with the multiple values these | |
895 | procedures return (@pxref{Multiple Values}). | |
896 | @end deffn | |
897 | ||
898 | ||
899 | @node SRFI-2 | |
900 | @section SRFI-2 - and-let* | |
8742c48b | 901 | @cindex SRFI-2 |
a0e07ba4 | 902 | |
4fd0db14 KR |
903 | @noindent |
904 | The following syntax can be obtained with | |
a0e07ba4 | 905 | |
4fd0db14 KR |
906 | @lisp |
907 | (use-modules (srfi srfi-2)) | |
908 | @end lisp | |
a0e07ba4 | 909 | |
4fd0db14 KR |
910 | @deffn {library syntax} and-let* (clause @dots{}) body @dots{} |
911 | A combination of @code{and} and @code{let*}. | |
912 | ||
913 | Each @var{clause} is evaluated in turn, and if @code{#f} is obtained | |
914 | then evaluation stops and @code{#f} is returned. If all are | |
915 | non-@code{#f} then @var{body} is evaluated and the last form gives the | |
916 | return value. Each @var{clause} should be one of the following, | |
917 | ||
918 | @table @code | |
919 | @item (symbol expr) | |
920 | Evaluate @var{expr}, check for @code{#f}, and bind it to @var{symbol}. | |
921 | Like @code{let*}, that binding is available to subsequent clauses. | |
922 | @item (expr) | |
923 | Evaluate @var{expr} and check for @code{#f}. | |
924 | @item symbol | |
925 | Get the value bound to @var{symbol} and check for @code{#f}. | |
926 | @end table | |
a0e07ba4 | 927 | |
4fd0db14 KR |
928 | Notice that @code{(expr)} has an ``extra'' pair of parentheses, for |
929 | instance @code{((eq? x y))}. One way to remember this is to imagine | |
930 | the @code{symbol} in @code{(symbol expr)} is omitted. | |
a0e07ba4 | 931 | |
4fd0db14 KR |
932 | @code{and-let*} is good for calculations where a @code{#f} value means |
933 | termination, but where a non-@code{#f} value is going to be needed in | |
934 | subsequent expressions. | |
935 | ||
936 | The following illustrates this, it returns text between brackets | |
937 | @samp{[...]} in a string, or @code{#f} if there are no such brackets | |
938 | (ie.@: either @code{string-index} gives @code{#f}). | |
939 | ||
940 | @example | |
941 | (define (extract-brackets str) | |
942 | (and-let* ((start (string-index str #\[)) | |
943 | (end (string-index str #\] start))) | |
944 | (substring str (1+ start) end))) | |
945 | @end example | |
946 | ||
947 | The following shows plain variables and expressions tested too. | |
948 | @code{diagnostic-levels} is taken to be an alist associating a | |
949 | diagnostic type with a level. @code{str} is printed only if the type | |
950 | is known and its level is high enough. | |
951 | ||
952 | @example | |
953 | (define (show-diagnostic type str) | |
954 | (and-let* (want-diagnostics | |
955 | (level (assq-ref diagnostic-levels type)) | |
956 | ((>= level current-diagnostic-level))) | |
957 | (display str))) | |
958 | @end example | |
959 | ||
960 | The advantage of @code{and-let*} is that an extended sequence of | |
961 | expressions and tests doesn't require lots of nesting as would arise | |
962 | from separate @code{and} and @code{let*}, or from @code{cond} with | |
963 | @code{=>}. | |
964 | ||
965 | @end deffn | |
a0e07ba4 NJ |
966 | |
967 | ||
968 | @node SRFI-4 | |
969 | @section SRFI-4 - Homogeneous numeric vector datatypes. | |
8742c48b | 970 | @cindex SRFI-4 |
a0e07ba4 NJ |
971 | |
972 | @c FIXME::martin: Review me! | |
973 | ||
974 | SRFI-4 defines a set of datatypes for vectors whose elements are all | |
975 | of the same numeric type. Vectors for signed and unsigned exact | |
976 | integer or inexact real numbers in several precisions are available. | |
977 | ||
978 | Procedures similar to the vector procedures (@pxref{Vectors}) are | |
979 | provided for handling these homogeneous vectors, but they are distinct | |
980 | datatypes. | |
981 | ||
982 | The reason for providing this set of datatypes is that with the | |
983 | limitation (all elements must have the same type), it is possible to | |
984 | implement them much more memory-efficient than normal, heterogenous | |
985 | vectors. | |
986 | ||
987 | If you want to use these datatypes and the corresponding procedures, | |
988 | you have to use the module @code{(srfi srfi-4)}. | |
989 | ||
990 | Ten vector data types are provided: Unsigned and signed integer values | |
991 | with 8, 16, 32 and 64 bits and floating point values with 32 and 64 | |
992 | bits. In the following descriptions, the tags @code{u8}, @code{s8}, | |
993 | @code{u16}, @code{s16}, @code{u32}, @code{s32}, @code{u64}, | |
994 | @code{s64}, @code{f32}, @code{f64}, respectively, are used for | |
995 | denoting the various types. | |
996 | ||
997 | @menu | |
998 | * SRFI-4 - Read Syntax:: How to write homogeneous vector literals. | |
999 | * SRFI-4 - Procedures:: Available homogeneous vector procedures. | |
1000 | @end menu | |
1001 | ||
1002 | ||
1003 | @node SRFI-4 - Read Syntax | |
1004 | @subsection SRFI-4 - Read Syntax | |
1005 | ||
1006 | Homogeneous numeric vectors have an external representation (read | |
1007 | syntax) similar to normal Scheme vectors, but with an additional tag | |
1008 | telling the vector's type. | |
1009 | ||
1010 | @lisp | |
1011 | #u16(1 2 3) | |
1012 | @end lisp | |
1013 | ||
1014 | denotes a homogeneous numeric vector of three elements, which are the | |
1015 | values 1, 2 and 3, represented as 16-bit unsigned integers. | |
1016 | Correspondingly, | |
1017 | ||
1018 | @lisp | |
1019 | #f64(3.1415 2.71) | |
1020 | @end lisp | |
1021 | ||
1022 | denotes a vector of two elements, which are the values 3.1415 and | |
1023 | 2.71, represented as floating-point values of 64 bit precision. | |
1024 | ||
1025 | Please note that the read syntax for floating-point vectors conflicts | |
1026 | with Standard Scheme, because there @code{#f} is defined to be the | |
1027 | literal false value. That means, that with the loaded SRFI-4 module, | |
1028 | it is not possible to enter some list like | |
1029 | ||
1030 | @lisp | |
1031 | '(1 #f3) | |
1032 | @end lisp | |
1033 | ||
1034 | and hope that it will be parsed as a three-element list with the | |
1035 | elements 1, @code{#f} and 3. In normal use, this should be no | |
1036 | problem, because people tend to terminate tokens sensibly when writing | |
1037 | Scheme expressions. | |
1038 | ||
1039 | @node SRFI-4 - Procedures | |
1040 | @subsection SRFI-4 Procedures | |
1041 | ||
1042 | The procedures listed in this section are provided for all homogeneous | |
1043 | numeric vector datatypes. For brevity, they are not all documented, | |
1044 | but a summary of the procedures is given. In the following | |
1045 | descriptions, you can replace @code{TAG} by any of the datatype | |
1046 | indicators @code{u8}, @code{s8}, @code{u16}, @code{s16}, @code{u32}, | |
1047 | @code{s32}, @code{u64}, @code{s64}, @code{f32} and @code{f64}. | |
1048 | ||
1049 | For example, you can use the procedures @code{u8vector?}, | |
1050 | @code{make-s8vector}, @code{u16vector}, @code{u32vector-length}, | |
1051 | @code{s64vector-ref}, @code{f32vector-set!} or @code{f64vector->list}. | |
1052 | ||
8f85c0c6 | 1053 | @deffn {Scheme Procedure} TAGvector? obj |
a0e07ba4 NJ |
1054 | Return @code{#t} if @var{obj} is a homogeneous numeric vector of type |
1055 | @code{TAG}. | |
1056 | @end deffn | |
1057 | ||
8f85c0c6 | 1058 | @deffn {Scheme Procedure} make-TAGvector n [value] |
a0e07ba4 NJ |
1059 | Create a newly allocated homogeneous numeric vector of type |
1060 | @code{TAG}, which can hold @var{n} elements. If @var{value} is given, | |
1061 | the vector is initialized with the value, otherwise, the contents of | |
1062 | the returned vector is not specified. | |
1063 | @end deffn | |
1064 | ||
8f85c0c6 | 1065 | @deffn {Scheme Procedure} TAGvector value1 @dots{} |
a0e07ba4 NJ |
1066 | Create a newly allocated homogeneous numeric vector of type |
1067 | @code{TAG}. The returned vector is as long as the number of arguments | |
1068 | given, and is initialized with the argument values. | |
1069 | @end deffn | |
1070 | ||
8f85c0c6 | 1071 | @deffn {Scheme Procedure} TAGvector-length TAGvec |
a0e07ba4 NJ |
1072 | Return the number of elements in @var{TAGvec}. |
1073 | @end deffn | |
1074 | ||
8f85c0c6 | 1075 | @deffn {Scheme Procedure} TAGvector-ref TAGvec i |
a0e07ba4 NJ |
1076 | Return the element at index @var{i} in @var{TAGvec}. |
1077 | @end deffn | |
1078 | ||
8f85c0c6 | 1079 | @deffn {Scheme Procedure} TAGvector-ref TAGvec i value |
a0e07ba4 NJ |
1080 | Set the element at index @var{i} in @var{TAGvec} to @var{value}. The |
1081 | return value is not specified. | |
1082 | @end deffn | |
1083 | ||
8f85c0c6 | 1084 | @deffn {Scheme Procedure} TAGvector->list TAGvec |
a0e07ba4 NJ |
1085 | Return a newly allocated list holding all elements of @var{TAGvec}. |
1086 | @end deffn | |
1087 | ||
8f85c0c6 | 1088 | @deffn {Scheme Procedure} list->TAGvector lst |
a0e07ba4 NJ |
1089 | Return a newly allocated homogeneous numeric vector of type @code{TAG}, |
1090 | initialized with the elements of the list @var{lst}. | |
1091 | @end deffn | |
1092 | ||
1093 | ||
1094 | @node SRFI-6 | |
1095 | @section SRFI-6 - Basic String Ports | |
8742c48b | 1096 | @cindex SRFI-6 |
a0e07ba4 NJ |
1097 | |
1098 | SRFI-6 defines the procedures @code{open-input-string}, | |
1099 | @code{open-output-string} and @code{get-output-string}. These | |
1100 | procedures are included in the Guile core, so using this module does not | |
1101 | make any difference at the moment. But it is possible that support for | |
1102 | SRFI-6 will be factored out of the core library in the future, so using | |
1103 | this module does not hurt, after all. | |
1104 | ||
1105 | @node SRFI-8 | |
1106 | @section SRFI-8 - receive | |
8742c48b | 1107 | @cindex SRFI-8 |
a0e07ba4 NJ |
1108 | |
1109 | @code{receive} is a syntax for making the handling of multiple-value | |
1110 | procedures easier. It is documented in @xref{Multiple Values}. | |
1111 | ||
1112 | ||
1113 | @node SRFI-9 | |
1114 | @section SRFI-9 - define-record-type | |
8742c48b | 1115 | @cindex SRFI-9 |
7ea6af07 | 1116 | @findex define-record-type |
a0e07ba4 NJ |
1117 | |
1118 | This is the SRFI way for defining record types. The Guile | |
1119 | implementation is a layer above Guile's normal record construction | |
1120 | procedures (@pxref{Records}). The nice thing about this kind of record | |
1121 | definition method is that no new names are implicitly created, all | |
1122 | constructor, accessor and predicates are explicitly given. This reduces | |
1123 | the risk of variable capture. | |
1124 | ||
1125 | The syntax of a record type definition is: | |
1126 | ||
1127 | @example | |
1128 | @group | |
1129 | <record type definition> | |
1130 | -> (define-record-type <type name> | |
1131 | (<constructor name> <field tag> ...) | |
1132 | <predicate name> | |
1133 | <field spec> ...) | |
1134 | <field spec> -> (<field tag> <accessor name>) | |
1135 | -> (<field tag> <accessor name> <modifier name>) | |
1136 | <field tag> -> <identifier> | |
1137 | <... name> -> <identifier> | |
1138 | @end group | |
1139 | @end example | |
1140 | ||
1141 | Usage example: | |
1142 | ||
1143 | @example | |
1144 | guile> (use-modules (srfi srfi-9)) | |
12991fed | 1145 | guile> (define-record-type :foo (make-foo x) foo? |
a0e07ba4 NJ |
1146 | (x get-x) (y get-y set-y!)) |
1147 | guile> (define f (make-foo 1)) | |
1148 | guile> f | |
1149 | #<:foo x: 1 y: #f> | |
1150 | guile> (get-x f) | |
1151 | 1 | |
1152 | guile> (set-y! f 2) | |
1153 | 2 | |
1154 | guile> (get-y f) | |
1155 | 2 | |
1156 | guile> f | |
1157 | #<:foo x: 1 y: 2> | |
1158 | guile> (foo? f) | |
1159 | #t | |
1160 | guile> (foo? 1) | |
1161 | #f | |
1162 | @end example | |
1163 | ||
1164 | ||
1165 | @node SRFI-10 | |
1166 | @section SRFI-10 - Hash-Comma Reader Extension | |
8742c48b | 1167 | @cindex SRFI-10 |
a0e07ba4 NJ |
1168 | |
1169 | @cindex hash-comma | |
1170 | @cindex #,() | |
1171 | The module @code{(srfi srfi-10)} implements the syntax extension | |
1172 | @code{#,()}, also called hash-comma, which is defined in SRFI-10. | |
1173 | ||
1174 | The support for SRFI-10 consists of the procedure | |
1175 | @code{define-reader-ctor} for defining new reader constructors and the | |
1176 | read syntax form | |
1177 | ||
1178 | @example | |
1179 | #,(@var{ctor} @var{datum} ...) | |
1180 | @end example | |
1181 | ||
1182 | where @var{ctor} must be a symbol for which a read constructor was | |
85a9b4ed | 1183 | defined previously, using @code{define-reader-ctor}. |
a0e07ba4 NJ |
1184 | |
1185 | Example: | |
1186 | ||
1187 | @lisp | |
4310df36 | 1188 | (use-modules (ice-9 rdelim)) ; for read-line |
a0e07ba4 NJ |
1189 | (define-reader-ctor 'file open-input-file) |
1190 | (define f '#,(file "/etc/passwd")) | |
1191 | (read-line f) | |
1192 | @result{} | |
1193 | "root:x:0:0:root:/root:/bin/bash" | |
1194 | @end lisp | |
1195 | ||
1196 | Please note the quote before the @code{#,(file ...)} expression. This | |
1197 | is necessary because ports are not self-evaluating in Guile. | |
1198 | ||
8f85c0c6 | 1199 | @deffn {Scheme Procedure} define-reader-ctor symbol proc |
a0e07ba4 NJ |
1200 | Define @var{proc} as the reader constructor for hash-comma forms with a |
1201 | tag @var{symbol}. @var{proc} will be applied to the datum(s) following | |
1202 | the tag in the hash-comma expression after the complete form has been | |
1203 | read in. The result of @var{proc} is returned by the Scheme reader. | |
1204 | @end deffn | |
1205 | ||
1206 | ||
1207 | @node SRFI-11 | |
1208 | @section SRFI-11 - let-values | |
8742c48b | 1209 | @cindex SRFI-11 |
a0e07ba4 | 1210 | |
8742c48b KR |
1211 | @findex let-values |
1212 | @findex let-values* | |
a0e07ba4 NJ |
1213 | This module implements the binding forms for multiple values |
1214 | @code{let-values} and @code{let-values*}. These forms are similar to | |
1215 | @code{let} and @code{let*} (@pxref{Local Bindings}), but they support | |
1216 | binding of the values returned by multiple-valued expressions. | |
1217 | ||
1218 | Write @code{(use-modules (srfi srfi-11))} to make the bindings | |
1219 | available. | |
1220 | ||
1221 | @lisp | |
1222 | (let-values (((x y) (values 1 2)) | |
1223 | ((z f) (values 3 4))) | |
1224 | (+ x y z f)) | |
1225 | @result{} | |
1226 | 10 | |
1227 | @end lisp | |
1228 | ||
1229 | @code{let-values} performs all bindings simultaneously, which means that | |
1230 | no expression in the binding clauses may refer to variables bound in the | |
1231 | same clause list. @code{let-values*}, on the other hand, performs the | |
1232 | bindings sequentially, just like @code{let*} does for single-valued | |
1233 | expressions. | |
1234 | ||
1235 | ||
1236 | @node SRFI-13 | |
1237 | @section SRFI-13 - String Library | |
8742c48b | 1238 | @cindex SRFI-13 |
a0e07ba4 NJ |
1239 | |
1240 | In this section, we will describe all procedures defined in SRFI-13 | |
1241 | (string library) and implemented by the module @code{(srfi srfi-13)}. | |
1242 | ||
1243 | Note that only the procedures from SRFI-13 are documented here which are | |
1244 | not already contained in Guile. For procedures not documented here | |
1245 | please refer to the relevant chapters in the Guile Reference Manual, for | |
1246 | example the documentation of strings and string procedures | |
1247 | (@pxref{Strings}). | |
1248 | ||
40f316d0 MG |
1249 | All of the procedures defined in SRFI-13, which are not already |
1250 | included in the Guile core library, are implemented in the module | |
1251 | @code{(srfi srfi-13)}. The procedures which are both in Guile and in | |
1252 | SRFI-13 are slightly extended in this module. Their bindings | |
1253 | overwrite those in the Guile core. | |
a0e07ba4 NJ |
1254 | |
1255 | The procedures which are defined in the section @emph{Low-level | |
1256 | procedures} of SRFI-13 for parsing optional string indices, substring | |
1257 | specification checking and Knuth-Morris-Pratt-Searching are not | |
1258 | implemented. | |
1259 | ||
1260 | The procedures @code{string-contains} and @code{string-contains-ci} are | |
1261 | not implemented very efficiently at the moment. This will be changed as | |
1262 | soon as possible. | |
1263 | ||
1264 | @menu | |
1265 | * Loading SRFI-13:: How to load SRFI-13 support. | |
1266 | * SRFI-13 Predicates:: String predicates. | |
1267 | * SRFI-13 Constructors:: String constructing procedures. | |
1268 | * SRFI-13 List/String Conversion:: Conversion from/to lists. | |
1269 | * SRFI-13 Selection:: Selection portions of strings. | |
85a9b4ed | 1270 | * SRFI-13 Modification:: Modify strings in-place. |
a0e07ba4 NJ |
1271 | * SRFI-13 Comparison:: Compare strings. |
1272 | * SRFI-13 Prefixes/Suffixes:: Detect common pre-/suffixes. | |
1273 | * SRFI-13 Searching:: Searching for substrings. | |
1274 | * SRFI-13 Case Mapping:: Mapping to lower-/upper-case. | |
1275 | * SRFI-13 Reverse/Append:: Reverse and append strings. | |
1276 | * SRFI-13 Fold/Unfold/Map:: Construct/deconstruct strings. | |
40f316d0 | 1277 | * SRFI-13 Replicate/Rotate:: Replicate and rotate portions of strings. |
a0e07ba4 NJ |
1278 | * SRFI-13 Miscellaneous:: Left-over string procedures. |
1279 | * SRFI-13 Filtering/Deleting:: Filter and delete characters from strings. | |
1280 | @end menu | |
1281 | ||
1282 | ||
1283 | @node Loading SRFI-13 | |
1284 | @subsection Loading SRFI-13 | |
1285 | ||
1286 | When Guile is properly installed, SRFI-13 support can be loaded into a | |
1287 | running Guile by using the @code{(srfi srfi-13)} module. | |
1288 | ||
1289 | @example | |
1290 | $ guile | |
1291 | guile> (use-modules (srfi srfi-13)) | |
1292 | guile> | |
1293 | @end example | |
1294 | ||
1295 | When this step causes any errors, Guile is not properly installed. | |
1296 | ||
1297 | One possible reason is that Guile cannot find either the Scheme module | |
1298 | file @file{srfi-13.scm}, or it cannot find the shared object file | |
1299 | @file{libguile-srfi-srfi-13-14.so}. Make sure that the former is in the | |
1300 | Guile load path and that the latter is either installed in some default | |
1301 | location like @file{/usr/local/lib} or that the directory it was | |
1302 | installed to is in your @code{LTDL_LIBRARY_PATH}. The same applies to | |
1303 | @file{srfi-14.scm}. | |
1304 | ||
1305 | Now you can test whether the SRFI-13 procedures are working by calling | |
1306 | the @code{string-concatenate} procedure. | |
1307 | ||
1308 | @example | |
1309 | guile> (string-concatenate '("Hello" " " "World!")) | |
1310 | "Hello World!" | |
1311 | @end example | |
1312 | ||
1313 | @node SRFI-13 Predicates | |
12991fed | 1314 | @subsection Predicates |
a0e07ba4 NJ |
1315 | |
1316 | In addition to the primitives @code{string?} and @code{string-null?}, | |
1317 | which are already in the Guile core, the string predicates | |
1318 | @code{string-any} and @code{string-every} are defined by SRFI-13. | |
1319 | ||
8f85c0c6 | 1320 | @deffn {Scheme Procedure} string-any pred s [start end] |
a0e07ba4 NJ |
1321 | Check if the predicate @var{pred} is true for any character in |
1322 | the string @var{s}, proceeding from left (index @var{start}) to | |
1323 | right (index @var{end}). If @code{string-any} returns true, | |
1324 | the returned true value is the one produced by the first | |
1325 | successful application of @var{pred}. | |
1326 | @end deffn | |
1327 | ||
8f85c0c6 | 1328 | @deffn {Scheme Procedure} string-every pred s [start end] |
a0e07ba4 NJ |
1329 | Check if the predicate @var{pred} is true for every character |
1330 | in the string @var{s}, proceeding from left (index @var{start}) | |
1331 | to right (index @var{end}). If @code{string-every} returns | |
1332 | true, the returned true value is the one produced by the final | |
1333 | application of @var{pred} to the last character of @var{s}. | |
1334 | @end deffn | |
1335 | ||
1336 | ||
1337 | @c =================================================================== | |
1338 | ||
1339 | @node SRFI-13 Constructors | |
1340 | @subsection Constructors | |
1341 | ||
1342 | SRFI-13 defines several procedures for constructing new strings. In | |
1343 | addition to @code{make-string} and @code{string} (available in the Guile | |
1344 | core library), the procedure @code{string-tabulate} does exist. | |
1345 | ||
8f85c0c6 | 1346 | @deffn {Scheme Procedure} string-tabulate proc len |
a0e07ba4 NJ |
1347 | @var{proc} is an integer->char procedure. Construct a string |
1348 | of size @var{len} by applying @var{proc} to each index to | |
1349 | produce the corresponding string element. The order in which | |
1350 | @var{proc} is applied to the indices is not specified. | |
1351 | @end deffn | |
1352 | ||
1353 | ||
1354 | @c =================================================================== | |
1355 | ||
1356 | @node SRFI-13 List/String Conversion | |
1357 | @subsection List/String Conversion | |
1358 | ||
1359 | The procedure @code{string->list} is extended by SRFI-13, that is why it | |
1360 | is included in @code{(srfi srfi-13)}. The other procedures are new. | |
1361 | The Guile core already contains the procedure @code{list->string} for | |
1362 | converting a list of characters into a string (@pxref{List/String | |
1363 | Conversion}). | |
1364 | ||
8f85c0c6 | 1365 | @deffn {Scheme Procedure} string->list str [start end] |
a0e07ba4 NJ |
1366 | Convert the string @var{str} into a list of characters. |
1367 | @end deffn | |
1368 | ||
8f85c0c6 | 1369 | @deffn {Scheme Procedure} reverse-list->string chrs |
a0e07ba4 NJ |
1370 | An efficient implementation of @code{(compose string->list |
1371 | reverse)}: | |
1372 | ||
1373 | @smalllisp | |
1374 | (reverse-list->string '(#\a #\B #\c)) @result{} "cBa" | |
1375 | @end smalllisp | |
1376 | @end deffn | |
1377 | ||
8f85c0c6 | 1378 | @deffn {Scheme Procedure} string-join ls [delimiter grammar] |
a0e07ba4 NJ |
1379 | Append the string in the string list @var{ls}, using the string |
1380 | @var{delim} as a delimiter between the elements of @var{ls}. | |
1381 | @var{grammar} is a symbol which specifies how the delimiter is | |
1382 | placed between the strings, and defaults to the symbol | |
1383 | @code{infix}. | |
1384 | ||
1385 | @table @code | |
1386 | @item infix | |
1387 | Insert the separator between list elements. An empty string | |
1388 | will produce an empty list. | |
1389 | ||
1390 | @item string-infix | |
1391 | Like @code{infix}, but will raise an error if given the empty | |
1392 | list. | |
1393 | ||
1394 | @item suffix | |
1395 | Insert the separator after every list element. | |
1396 | ||
1397 | @item prefix | |
1398 | Insert the separator before each list element. | |
1399 | @end table | |
1400 | @end deffn | |
1401 | ||
1402 | ||
1403 | @c =================================================================== | |
1404 | ||
1405 | @node SRFI-13 Selection | |
1406 | @subsection Selection | |
1407 | ||
1408 | These procedures are called @dfn{selectors}, because they access | |
1409 | information about the string or select pieces of a given string. | |
1410 | ||
1411 | Additional selector procedures are documented in the Strings section | |
1412 | (@pxref{String Selection}), like @code{string-length} or | |
1413 | @code{string-ref}. | |
1414 | ||
1415 | @code{string-copy} is also available in core Guile, but this version | |
1416 | accepts additional start/end indices. | |
1417 | ||
8f85c0c6 | 1418 | @deffn {Scheme Procedure} string-copy str [start end] |
a0e07ba4 NJ |
1419 | Return a freshly allocated copy of the string @var{str}. If |
1420 | given, @var{start} and @var{end} delimit the portion of | |
1421 | @var{str} which is copied. | |
1422 | @end deffn | |
1423 | ||
8f85c0c6 | 1424 | @deffn {Scheme Procedure} substring/shared str start [end] |
a0e07ba4 NJ |
1425 | Like @code{substring}, but the result may share memory with the |
1426 | argument @var{str}. | |
1427 | @end deffn | |
1428 | ||
8f85c0c6 | 1429 | @deffn {Scheme Procedure} string-copy! target tstart s [start end] |
a0e07ba4 NJ |
1430 | Copy the sequence of characters from index range [@var{start}, |
1431 | @var{end}) in string @var{s} to string @var{target}, beginning | |
1432 | at index @var{tstart}. The characters are copied left-to-right | |
1433 | or right-to-left as needed - the copy is guaranteed to work, | |
1434 | even if @var{target} and @var{s} are the same string. It is an | |
1435 | error if the copy operation runs off the end of the target | |
1436 | string. | |
1437 | @end deffn | |
1438 | ||
8f85c0c6 NJ |
1439 | @deffn {Scheme Procedure} string-take s n |
1440 | @deffnx {Scheme Procedure} string-take-right s n | |
a0e07ba4 NJ |
1441 | Return the @var{n} first/last characters of @var{s}. |
1442 | @end deffn | |
1443 | ||
8f85c0c6 NJ |
1444 | @deffn {Scheme Procedure} string-drop s n |
1445 | @deffnx {Scheme Procedure} string-drop-right s n | |
a0e07ba4 NJ |
1446 | Return all but the first/last @var{n} characters of @var{s}. |
1447 | @end deffn | |
1448 | ||
8f85c0c6 NJ |
1449 | @deffn {Scheme Procedure} string-pad s len [chr start end] |
1450 | @deffnx {Scheme Procedure} string-pad-right s len [chr start end] | |
a0e07ba4 NJ |
1451 | Take that characters from @var{start} to @var{end} from the |
1452 | string @var{s} and return a new string, right(left)-padded by the | |
1453 | character @var{chr} to length @var{len}. If the resulting | |
1454 | string is longer than @var{len}, it is truncated on the right (left). | |
1455 | @end deffn | |
1456 | ||
8f85c0c6 NJ |
1457 | @deffn {Scheme Procedure} string-trim s [char_pred start end] |
1458 | @deffnx {Scheme Procedure} string-trim-right s [char_pred start end] | |
1459 | @deffnx {Scheme Procedure} string-trim-both s [char_pred start end] | |
a0e07ba4 NJ |
1460 | Trim @var{s} by skipping over all characters on the left/right/both |
1461 | sides of the string that satisfy the parameter @var{char_pred}: | |
1462 | ||
1463 | @itemize @bullet | |
1464 | @item | |
1465 | if it is the character @var{ch}, characters equal to | |
1466 | @var{ch} are trimmed, | |
1467 | ||
1468 | @item | |
1469 | if it is a procedure @var{pred} characters that | |
1470 | satisfy @var{pred} are trimmed, | |
1471 | ||
1472 | @item | |
1473 | if it is a character set, characters in that set are trimmed. | |
1474 | @end itemize | |
1475 | ||
1476 | If called without a @var{char_pred} argument, all whitespace is | |
1477 | trimmed. | |
1478 | @end deffn | |
1479 | ||
1480 | ||
1481 | @c =================================================================== | |
1482 | ||
1483 | @node SRFI-13 Modification | |
1484 | @subsection Modification | |
1485 | ||
1486 | The procedure @code{string-fill!} is extended from R5RS because it | |
1487 | accepts optional start/end indices. This bindings shadows the procedure | |
1488 | of the same name in the Guile core. The second modification procedure | |
1489 | @code{string-set!} is documented in the Strings section (@pxref{String | |
1490 | Modification}). | |
1491 | ||
8f85c0c6 | 1492 | @deffn {Scheme Procedure} string-fill! str chr [start end] |
a0e07ba4 NJ |
1493 | Stores @var{chr} in every element of the given @var{str} and |
1494 | returns an unspecified value. | |
1495 | @end deffn | |
1496 | ||
1497 | ||
1498 | @c =================================================================== | |
1499 | ||
1500 | @node SRFI-13 Comparison | |
1501 | @subsection Comparison | |
1502 | ||
1503 | The procedures in this section are used for comparing strings in | |
1504 | different ways. The comparison predicates differ from those in R5RS in | |
1505 | that they do not only return @code{#t} or @code{#f}, but the mismatch | |
1506 | index in the case of a true return value. | |
1507 | ||
1508 | @code{string-hash} and @code{string-hash-ci} are for calculating hash | |
1509 | values for strings, useful for implementing fast lookup mechanisms. | |
1510 | ||
8f85c0c6 NJ |
1511 | @deffn {Scheme Procedure} string-compare s1 s2 proc_lt proc_eq proc_gt [start1 end1 start2 end2] |
1512 | @deffnx {Scheme Procedure} string-compare-ci s1 s2 proc_lt proc_eq proc_gt [start1 end1 start2 end2] | |
a0e07ba4 NJ |
1513 | Apply @var{proc_lt}, @var{proc_eq}, @var{proc_gt} to the |
1514 | mismatch index, depending upon whether @var{s1} is less than, | |
1515 | equal to, or greater than @var{s2}. The mismatch index is the | |
1516 | largest index @var{i} such that for every 0 <= @var{j} < | |
1517 | @var{i}, @var{s1}[@var{j}] = @var{s2}[@var{j}] - that is, | |
1518 | @var{i} is the first position that does not match. The | |
1519 | character comparison is done case-insensitively. | |
1520 | @end deffn | |
1521 | ||
8f85c0c6 NJ |
1522 | @deffn {Scheme Procedure} string= s1 s2 [start1 end1 start2 end2] |
1523 | @deffnx {Scheme Procedure} string<> s1 s2 [start1 end1 start2 end2] | |
1524 | @deffnx {Scheme Procedure} string< s1 s2 [start1 end1 start2 end2] | |
1525 | @deffnx {Scheme Procedure} string> s1 s2 [start1 end1 start2 end2] | |
1526 | @deffnx {Scheme Procedure} string<= s1 s2 [start1 end1 start2 end2] | |
1527 | @deffnx {Scheme Procedure} string>= s1 s2 [start1 end1 start2 end2] | |
a0e07ba4 NJ |
1528 | Compare @var{s1} and @var{s2} and return @code{#f} if the predicate |
1529 | fails. Otherwise, the mismatch index is returned (or @var{end1} in the | |
1530 | case of @code{string=}. | |
1531 | @end deffn | |
1532 | ||
8f85c0c6 NJ |
1533 | @deffn {Scheme Procedure} string-ci= s1 s2 [start1 end1 start2 end2] |
1534 | @deffnx {Scheme Procedure} string-ci<> s1 s2 [start1 end1 start2 end2] | |
1535 | @deffnx {Scheme Procedure} string-ci< s1 s2 [start1 end1 start2 end2] | |
1536 | @deffnx {Scheme Procedure} string-ci> s1 s2 [start1 end1 start2 end2] | |
1537 | @deffnx {Scheme Procedure} string-ci<= s1 s2 [start1 end1 start2 end2] | |
1538 | @deffnx {Scheme Procedure} string-ci>= s1 s2 [start1 end1 start2 end2] | |
a0e07ba4 NJ |
1539 | Compare @var{s1} and @var{s2} and return @code{#f} if the predicate |
1540 | fails. Otherwise, the mismatch index is returned (or @var{end1} in the | |
1541 | case of @code{string=}. These are the case-insensitive variants. | |
1542 | @end deffn | |
1543 | ||
8f85c0c6 NJ |
1544 | @deffn {Scheme Procedure} string-hash s [bound start end] |
1545 | @deffnx {Scheme Procedure} string-hash-ci s [bound start end] | |
a0e07ba4 NJ |
1546 | Return a hash value of the string @var{s} in the range 0 @dots{} |
1547 | @var{bound} - 1. @code{string-hash-ci} is the case-insensitive variant. | |
1548 | @end deffn | |
1549 | ||
1550 | ||
1551 | @c =================================================================== | |
1552 | ||
1553 | @node SRFI-13 Prefixes/Suffixes | |
1554 | @subsection Prefixes/Suffixes | |
1555 | ||
1556 | Using these procedures you can determine whether a given string is a | |
1557 | prefix or suffix of another string or how long a common prefix/suffix | |
1558 | is. | |
1559 | ||
8f85c0c6 NJ |
1560 | @deffn {Scheme Procedure} string-prefix-length s1 s2 [start1 end1 start2 end2] |
1561 | @deffnx {Scheme Procedure} string-prefix-length-ci s1 s2 [start1 end1 start2 end2] | |
1562 | @deffnx {Scheme Procedure} string-suffix-length s1 s2 [start1 end1 start2 end2] | |
1563 | @deffnx {Scheme Procedure} string-suffix-length-ci s1 s2 [start1 end1 start2 end2] | |
a0e07ba4 NJ |
1564 | Return the length of the longest common prefix/suffix of the two |
1565 | strings. @code{string-prefix-length-ci} and | |
1566 | @code{string-suffix-length-ci} are the case-insensitive variants. | |
1567 | @end deffn | |
1568 | ||
8f85c0c6 NJ |
1569 | @deffn {Scheme Procedure} string-prefix? s1 s2 [start1 end1 start2 end2] |
1570 | @deffnx {Scheme Procedure} string-prefix-ci? s1 s2 [start1 end1 start2 end2] | |
1571 | @deffnx {Scheme Procedure} string-suffix? s1 s2 [start1 end1 start2 end2] | |
1572 | @deffnx {Scheme Procedure} string-suffix-ci? s1 s2 [start1 end1 start2 end2] | |
a0e07ba4 NJ |
1573 | Is @var{s1} a prefix/suffix of @var{s2}. @code{string-prefix-ci?} and |
1574 | @code{string-suffix-ci?} are the case-insensitive variants. | |
1575 | @end deffn | |
1576 | ||
1577 | ||
1578 | @c =================================================================== | |
1579 | ||
1580 | @node SRFI-13 Searching | |
1581 | @subsection Searching | |
1582 | ||
1583 | Use these procedures to find out whether a string contains a given | |
1584 | character or a given substring, or a character from a set of characters. | |
1585 | ||
8f85c0c6 NJ |
1586 | @deffn {Scheme Procedure} string-index s char_pred [start end] |
1587 | @deffnx {Scheme Procedure} string-index-right s char_pred [start end] | |
a0e07ba4 | 1588 | Search through the string @var{s} from left to right (right to left), |
85a9b4ed | 1589 | returning the index of the first (last) occurrence of a character which |
a0e07ba4 NJ |
1590 | |
1591 | @itemize @bullet | |
1592 | @item | |
1593 | equals @var{char_pred}, if it is character, | |
1594 | ||
1595 | @item | |
85a9b4ed | 1596 | satisfies the predicate @var{char_pred}, if it is a |
a0e07ba4 NJ |
1597 | procedure, |
1598 | ||
1599 | @item | |
1600 | is in the set @var{char_pred}, if it is a character set. | |
1601 | @end itemize | |
1602 | @end deffn | |
1603 | ||
8f85c0c6 NJ |
1604 | @deffn {Scheme Procedure} string-skip s char_pred [start end] |
1605 | @deffnx {Scheme Procedure} string-skip-right s char_pred [start end] | |
a0e07ba4 | 1606 | Search through the string @var{s} from left to right (right to left), |
85a9b4ed | 1607 | returning the index of the first (last) occurrence of a character which |
a0e07ba4 NJ |
1608 | |
1609 | @itemize @bullet | |
1610 | @item | |
1611 | does not equal @var{char_pred}, if it is character, | |
1612 | ||
1613 | @item | |
85a9b4ed | 1614 | does not satisfy the predicate @var{char_pred}, if it is |
a0e07ba4 NJ |
1615 | a procedure. |
1616 | ||
1617 | @item | |
1618 | is not in the set if @var{char_pred} is a character set. | |
1619 | @end itemize | |
1620 | @end deffn | |
1621 | ||
8f85c0c6 | 1622 | @deffn {Scheme Procedure} string-count s char_pred [start end] |
a0e07ba4 NJ |
1623 | Return the count of the number of characters in the string |
1624 | @var{s} which | |
1625 | ||
1626 | @itemize @bullet | |
1627 | @item | |
1628 | equals @var{char_pred}, if it is character, | |
1629 | ||
1630 | @item | |
85a9b4ed | 1631 | satisfies the predicate @var{char_pred}, if it is a procedure. |
a0e07ba4 NJ |
1632 | |
1633 | @item | |
1634 | is in the set @var{char_pred}, if it is a character set. | |
1635 | @end itemize | |
1636 | @end deffn | |
1637 | ||
8f85c0c6 NJ |
1638 | @deffn {Scheme Procedure} string-contains s1 s2 [start1 end1 start2 end2] |
1639 | @deffnx {Scheme Procedure} string-contains-ci s1 s2 [start1 end1 start2 end2] | |
a0e07ba4 NJ |
1640 | Does string @var{s1} contain string @var{s2}? Return the index |
1641 | in @var{s1} where @var{s2} occurs as a substring, or false. | |
1642 | The optional start/end indices restrict the operation to the | |
1643 | indicated substrings. | |
1644 | ||
1645 | @code{string-contains-ci} is the case-insensitive variant. | |
1646 | @end deffn | |
1647 | ||
1648 | ||
1649 | @c =================================================================== | |
1650 | ||
1651 | @node SRFI-13 Case Mapping | |
1652 | @subsection Alphabetic Case Mapping | |
1653 | ||
1654 | These procedures convert the alphabetic case of strings. They are | |
1655 | similar to the procedures in the Guile core, but are extended to handle | |
1656 | optional start/end indices. | |
1657 | ||
8f85c0c6 NJ |
1658 | @deffn {Scheme Procedure} string-upcase s [start end] |
1659 | @deffnx {Scheme Procedure} string-upcase! s [start end] | |
a0e07ba4 NJ |
1660 | Upcase every character in @var{s}. @code{string-upcase!} is the |
1661 | side-effecting variant. | |
1662 | @end deffn | |
1663 | ||
8f85c0c6 NJ |
1664 | @deffn {Scheme Procedure} string-downcase s [start end] |
1665 | @deffnx {Scheme Procedure} string-downcase! s [start end] | |
a0e07ba4 NJ |
1666 | Downcase every character in @var{s}. @code{string-downcase!} is the |
1667 | side-effecting variant. | |
1668 | @end deffn | |
1669 | ||
8f85c0c6 NJ |
1670 | @deffn {Scheme Procedure} string-titlecase s [start end] |
1671 | @deffnx {Scheme Procedure} string-titlecase! s [start end] | |
a0e07ba4 NJ |
1672 | Upcase every first character in every word in @var{s}, downcase the |
1673 | other characters. @code{string-titlecase!} is the side-effecting | |
1674 | variant. | |
1675 | @end deffn | |
1676 | ||
1677 | ||
1678 | @c =================================================================== | |
1679 | ||
1680 | @node SRFI-13 Reverse/Append | |
1681 | @subsection Reverse/Append | |
1682 | ||
1683 | One appending procedure, @code{string-append} is the same in R5RS and in | |
1684 | SRFI-13, so it is not redefined. | |
1685 | ||
8f85c0c6 NJ |
1686 | @deffn {Scheme Procedure} string-reverse str [start end] |
1687 | @deffnx {Scheme Procedure} string-reverse! str [start end] | |
a0e07ba4 NJ |
1688 | Reverse the string @var{str}. The optional arguments |
1689 | @var{start} and @var{end} delimit the region of @var{str} to | |
1690 | operate on. | |
1691 | ||
1692 | @code{string-reverse!} modifies the argument string and returns an | |
1693 | unspecified value. | |
1694 | @end deffn | |
1695 | ||
8f85c0c6 | 1696 | @deffn {Scheme Procedure} string-append/shared ls @dots{} |
a0e07ba4 NJ |
1697 | Like @code{string-append}, but the result may share memory |
1698 | with the argument strings. | |
1699 | @end deffn | |
1700 | ||
8f85c0c6 | 1701 | @deffn {Scheme Procedure} string-concatenate ls |
a0e07ba4 NJ |
1702 | Append the elements of @var{ls} (which must be strings) |
1703 | together into a single string. Guaranteed to return a freshly | |
1704 | allocated string. | |
1705 | @end deffn | |
1706 | ||
8f85c0c6 | 1707 | @deffn {Scheme Procedure} string-concatenate/shared ls |
a0e07ba4 NJ |
1708 | Like @code{string-concatenate}, but the result may share memory |
1709 | with the strings in the list @var{ls}. | |
1710 | @end deffn | |
1711 | ||
8f85c0c6 | 1712 | @deffn {Scheme Procedure} string-concatenate-reverse ls final_string end |
a0e07ba4 NJ |
1713 | Without optional arguments, this procedure is equivalent to |
1714 | ||
1715 | @smalllisp | |
1716 | (string-concatenate (reverse ls)) | |
1717 | @end smalllisp | |
1718 | ||
1719 | If the optional argument @var{final_string} is specified, it is | |
1720 | consed onto the beginning to @var{ls} before performing the | |
1721 | list-reverse and string-concatenate operations. If @var{end} | |
1722 | is given, only the characters of @var{final_string} up to index | |
1723 | @var{end} are used. | |
1724 | ||
1725 | Guaranteed to return a freshly allocated string. | |
1726 | @end deffn | |
1727 | ||
8f85c0c6 | 1728 | @deffn {Scheme Procedure} string-concatenate-reverse/shared ls final_string end |
a0e07ba4 NJ |
1729 | Like @code{string-concatenate-reverse}, but the result may |
1730 | share memory with the the strings in the @var{ls} arguments. | |
1731 | @end deffn | |
1732 | ||
1733 | ||
1734 | @c =================================================================== | |
1735 | ||
1736 | @node SRFI-13 Fold/Unfold/Map | |
1737 | @subsection Fold/Unfold/Map | |
1738 | ||
1739 | @code{string-map}, @code{string-for-each} etc. are for iterating over | |
1740 | the characters a string is composed of. The fold and unfold procedures | |
1741 | are list iterators and constructors. | |
1742 | ||
8f85c0c6 | 1743 | @deffn {Scheme Procedure} string-map proc s [start end] |
a0e07ba4 NJ |
1744 | @var{proc} is a char->char procedure, it is mapped over |
1745 | @var{s}. The order in which the procedure is applied to the | |
1746 | string elements is not specified. | |
1747 | @end deffn | |
1748 | ||
8f85c0c6 | 1749 | @deffn {Scheme Procedure} string-map! proc s [start end] |
a0e07ba4 NJ |
1750 | @var{proc} is a char->char procedure, it is mapped over |
1751 | @var{s}. The order in which the procedure is applied to the | |
1752 | string elements is not specified. The string @var{s} is | |
1753 | modified in-place, the return value is not specified. | |
1754 | @end deffn | |
1755 | ||
8f85c0c6 NJ |
1756 | @deffn {Scheme Procedure} string-fold kons knil s [start end] |
1757 | @deffnx {Scheme Procedure} string-fold-right kons knil s [start end] | |
a0e07ba4 NJ |
1758 | Fold @var{kons} over the characters of @var{s}, with @var{knil} as the |
1759 | terminating element, from left to right (or right to left, for | |
1760 | @code{string-fold-right}). @var{kons} must expect two arguments: The | |
1761 | actual character and the last result of @var{kons}' application. | |
1762 | @end deffn | |
1763 | ||
8f85c0c6 NJ |
1764 | @deffn {Scheme Procedure} string-unfold p f g seed [base make_final] |
1765 | @deffnx {Scheme Procedure} string-unfold-right p f g seed [base make_final] | |
a0e07ba4 NJ |
1766 | These are the fundamental string constructors. |
1767 | @itemize @bullet | |
1768 | @item @var{g} is used to generate a series of @emph{seed} | |
1769 | values from the initial @var{seed}: @var{seed}, (@var{g} | |
1770 | @var{seed}), (@var{g}^2 @var{seed}), (@var{g}^3 @var{seed}), | |
1771 | @dots{} | |
1772 | @item @var{p} tells us when to stop - when it returns true | |
1773 | when applied to one of these seed values. | |
12991fed | 1774 | @item @var{f} maps each seed value to the corresponding |
a0e07ba4 NJ |
1775 | character in the result string. These chars are assembled into the |
1776 | string in a left-to-right (right-to-left) order. | |
1777 | @item @var{base} is the optional initial/leftmost (rightmost) | |
1778 | portion of the constructed string; it default to the empty string. | |
1779 | @item @var{make_final} is applied to the terminal seed | |
1780 | value (on which @var{p} returns true) to produce the final/rightmost | |
1781 | (leftmost) portion of the constructed string. It defaults to | |
1782 | @code{(lambda (x) "")}. | |
1783 | @end itemize | |
1784 | @end deffn | |
1785 | ||
8f85c0c6 | 1786 | @deffn {Scheme Procedure} string-for-each proc s [start end] |
a0e07ba4 NJ |
1787 | @var{proc} is mapped over @var{s} in left-to-right order. The |
1788 | return value is not specified. | |
1789 | @end deffn | |
1790 | ||
1791 | ||
1792 | @c =================================================================== | |
1793 | ||
1794 | @node SRFI-13 Replicate/Rotate | |
1795 | @subsection Replicate/Rotate | |
1796 | ||
1797 | These procedures are special substring procedures, which can also be | |
1798 | used for replicating strings. They are a bit tricky to use, but | |
1799 | consider this code fragment, which replicates the input string | |
1800 | @code{"foo"} so often that the resulting string has a length of six. | |
1801 | ||
1802 | @lisp | |
1803 | (xsubstring "foo" 0 6) | |
1804 | @result{} | |
1805 | "foofoo" | |
1806 | @end lisp | |
1807 | ||
8f85c0c6 | 1808 | @deffn {Scheme Procedure} xsubstring s from [to start end] |
a0e07ba4 NJ |
1809 | This is the @emph{extended substring} procedure that implements |
1810 | replicated copying of a substring of some string. | |
1811 | ||
1812 | @var{s} is a string, @var{start} and @var{end} are optional | |
1813 | arguments that demarcate a substring of @var{s}, defaulting to | |
1814 | 0 and the length of @var{s}. Replicate this substring up and | |
1815 | down index space, in both the positive and negative directions. | |
1816 | @code{xsubstring} returns the substring of this string | |
1817 | beginning at index @var{from}, and ending at @var{to}, which | |
1818 | defaults to @var{from} + (@var{end} - @var{start}). | |
1819 | @end deffn | |
1820 | ||
8f85c0c6 | 1821 | @deffn {Scheme Procedure} string-xcopy! target tstart s sfrom [sto start end] |
a0e07ba4 NJ |
1822 | Exactly the same as @code{xsubstring}, but the extracted text |
1823 | is written into the string @var{target} starting at index | |
1824 | @var{tstart}. The operation is not defined if @code{(eq? | |
1825 | @var{target} @var{s})} or these arguments share storage - you | |
1826 | cannot copy a string on top of itself. | |
1827 | @end deffn | |
1828 | ||
1829 | ||
1830 | @c =================================================================== | |
1831 | ||
1832 | @node SRFI-13 Miscellaneous | |
1833 | @subsection Miscellaneous | |
1834 | ||
1835 | @code{string-replace} is for replacing a portion of a string with | |
1836 | another string and @code{string-tokenize} splits a string into a list of | |
1837 | strings, breaking it up at a specified character. | |
1838 | ||
8c24f46e | 1839 | @deffn {Scheme Procedure} string-replace s1 s2 [start1 end1 start2 end2] |
a0e07ba4 NJ |
1840 | Return the string @var{s1}, but with the characters |
1841 | @var{start1} @dots{} @var{end1} replaced by the characters | |
1842 | @var{start2} @dots{} @var{end2} from @var{s2}. | |
5519096e KR |
1843 | |
1844 | For reference, note that SRFI-13 specifies @var{start1} and @var{end1} | |
1845 | as mandatory, but in Guile they are optional. | |
a0e07ba4 NJ |
1846 | @end deffn |
1847 | ||
c0ab7f13 | 1848 | @deffn {Scheme Procedure} string-tokenize s [token-set start end] |
a0e07ba4 | 1849 | Split the string @var{s} into a list of substrings, where each |
c0ab7f13 MV |
1850 | substring is a maximal non-empty contiguous sequence of characters |
1851 | from the character set @var{token_set}, which defaults to an | |
1852 | equivalent of @code{char-set:graphic}. If @var{start} or @var{end} | |
1853 | indices are provided, they restrict @code{string-tokenize} to | |
1854 | operating on the indicated substring of @var{s}. | |
a0e07ba4 NJ |
1855 | @end deffn |
1856 | ||
1857 | ||
1858 | @c =================================================================== | |
1859 | ||
1860 | @node SRFI-13 Filtering/Deleting | |
1861 | @subsection Filtering/Deleting | |
1862 | ||
1863 | @dfn{Filtering} means to remove all characters from a string which do | |
1864 | not match a given criteria, @dfn{deleting} means the opposite. | |
1865 | ||
8f85c0c6 | 1866 | @deffn {Scheme Procedure} string-filter s char_pred [start end] |
a0e07ba4 NJ |
1867 | Filter the string @var{s}, retaining only those characters that |
1868 | satisfy the @var{char_pred} argument. If the argument is a | |
1869 | procedure, it is applied to each character as a predicate, if | |
1870 | it is a character, it is tested for equality and if it is a | |
1871 | character set, it is tested for membership. | |
1872 | @end deffn | |
1873 | ||
8f85c0c6 | 1874 | @deffn {Scheme Procedure} string-delete s char_pred [start end] |
a0e07ba4 NJ |
1875 | Filter the string @var{s}, retaining only those characters that |
1876 | do not satisfy the @var{char_pred} argument. If the argument | |
1877 | is a procedure, it is applied to each character as a predicate, | |
1878 | if it is a character, it is tested for equality and if it is a | |
1879 | character set, it is tested for membership. | |
1880 | @end deffn | |
1881 | ||
1882 | ||
1883 | @node SRFI-14 | |
1884 | @section SRFI-14 - Character-set Library | |
8742c48b | 1885 | @cindex SRFI-14 |
a0e07ba4 NJ |
1886 | |
1887 | SRFI-14 defines the data type @dfn{character set}, and also defines a | |
1888 | lot of procedures for handling this character type, and a few standard | |
1889 | character sets like whitespace, alphabetic characters and others. | |
1890 | ||
1891 | All procedures from SRFI-14 (character-set library) are implemented in | |
1892 | the module @code{(srfi srfi-14)}, as well as the standard variables | |
1893 | @code{char-set:letter}, @code{char-set:digit} etc. | |
1894 | ||
1895 | @menu | |
1896 | * Loading SRFI-14:: How to make charsets available. | |
1897 | * SRFI-14 Character Set Data Type:: Underlying data type for charsets. | |
1898 | * SRFI-14 Predicates/Comparison:: Charset predicates. | |
1899 | * SRFI-14 Iterating Over Character Sets:: Enumerate charset elements. | |
85a9b4ed | 1900 | * SRFI-14 Creating Character Sets:: Making new charsets. |
a0e07ba4 NJ |
1901 | * SRFI-14 Querying Character Sets:: Test charsets for membership etc. |
1902 | * SRFI-14 Character-Set Algebra:: Calculating new charsets. | |
1903 | * SRFI-14 Standard Character Sets:: Variables containing predefined charsets. | |
1904 | @end menu | |
1905 | ||
1906 | ||
1907 | @node Loading SRFI-14 | |
1908 | @subsection Loading SRFI-14 | |
1909 | ||
1910 | When Guile is properly installed, SRFI-14 support can be loaded into a | |
1911 | running Guile by using the @code{(srfi srfi-14)} module. | |
1912 | ||
1913 | @example | |
1914 | $ guile | |
1915 | guile> (use-modules (srfi srfi-14)) | |
1916 | guile> (char-set-union (char-set #\f #\o #\o) (string->char-set "bar")) | |
1917 | #<charset @{#\a #\b #\f #\o #\r@}> | |
1918 | guile> | |
1919 | @end example | |
1920 | ||
1921 | ||
1922 | @node SRFI-14 Character Set Data Type | |
1923 | @subsection Character Set Data Type | |
1924 | ||
1925 | The data type @dfn{charset} implements sets of characters | |
1926 | (@pxref{Characters}). Because the internal representation of character | |
1927 | sets is not visible to the user, a lot of procedures for handling them | |
1928 | are provided. | |
1929 | ||
1930 | Character sets can be created, extended, tested for the membership of a | |
1931 | characters and be compared to other character sets. | |
1932 | ||
1933 | The Guile implementation of character sets deals with 8-bit characters. | |
1934 | In the standard variables, only the ASCII part of the character range is | |
1935 | really used, so that for example @dfn{Umlaute} and other accented | |
1936 | characters are not considered to be letters. In the future, as Guile | |
1937 | may get support for international character sets, this will change, so | |
1938 | don't rely on these ``features''. | |
1939 | ||
1940 | ||
1941 | @c =================================================================== | |
1942 | ||
1943 | @node SRFI-14 Predicates/Comparison | |
1944 | @subsection Predicates/Comparison | |
1945 | ||
1946 | Use these procedures for testing whether an object is a character set, | |
1947 | or whether several character sets are equal or subsets of each other. | |
1948 | @code{char-set-hash} can be used for calculating a hash value, maybe for | |
1949 | usage in fast lookup procedures. | |
1950 | ||
8f85c0c6 | 1951 | @deffn {Scheme Procedure} char-set? obj |
a0e07ba4 NJ |
1952 | Return @code{#t} if @var{obj} is a character set, @code{#f} |
1953 | otherwise. | |
1954 | @end deffn | |
1955 | ||
8f85c0c6 | 1956 | @deffn {Scheme Procedure} char-set= cs1 @dots{} |
a0e07ba4 NJ |
1957 | Return @code{#t} if all given character sets are equal. |
1958 | @end deffn | |
1959 | ||
8f85c0c6 | 1960 | @deffn {Scheme Procedure} char-set<= cs1 @dots{} |
a0e07ba4 NJ |
1961 | Return @code{#t} if every character set @var{cs}i is a subset |
1962 | of character set @var{cs}i+1. | |
1963 | @end deffn | |
1964 | ||
8f85c0c6 | 1965 | @deffn {Scheme Procedure} char-set-hash cs [bound] |
a0e07ba4 NJ |
1966 | Compute a hash value for the character set @var{cs}. If |
1967 | @var{bound} is given and not @code{#f}, it restricts the | |
1968 | returned value to the range 0 @dots{} @var{bound - 1}. | |
1969 | @end deffn | |
1970 | ||
1971 | ||
1972 | @c =================================================================== | |
1973 | ||
1974 | @node SRFI-14 Iterating Over Character Sets | |
1975 | @subsection Iterating Over Character Sets | |
1976 | ||
1977 | Character set cursors are a means for iterating over the members of a | |
1978 | character sets. After creating a character set cursor with | |
1979 | @code{char-set-cursor}, a cursor can be dereferenced with | |
1980 | @code{char-set-ref}, advanced to the next member with | |
1981 | @code{char-set-cursor-next}. Whether a cursor has passed past the last | |
1982 | element of the set can be checked with @code{end-of-char-set?}. | |
1983 | ||
1984 | Additionally, mapping and (un-)folding procedures for character sets are | |
1985 | provided. | |
1986 | ||
8f85c0c6 | 1987 | @deffn {Scheme Procedure} char-set-cursor cs |
a0e07ba4 NJ |
1988 | Return a cursor into the character set @var{cs}. |
1989 | @end deffn | |
1990 | ||
8f85c0c6 | 1991 | @deffn {Scheme Procedure} char-set-ref cs cursor |
a0e07ba4 NJ |
1992 | Return the character at the current cursor position |
1993 | @var{cursor} in the character set @var{cs}. It is an error to | |
1994 | pass a cursor for which @code{end-of-char-set?} returns true. | |
1995 | @end deffn | |
1996 | ||
8f85c0c6 | 1997 | @deffn {Scheme Procedure} char-set-cursor-next cs cursor |
a0e07ba4 NJ |
1998 | Advance the character set cursor @var{cursor} to the next |
1999 | character in the character set @var{cs}. It is an error if the | |
2000 | cursor given satisfies @code{end-of-char-set?}. | |
2001 | @end deffn | |
2002 | ||
8f85c0c6 | 2003 | @deffn {Scheme Procedure} end-of-char-set? cursor |
a0e07ba4 NJ |
2004 | Return @code{#t} if @var{cursor} has reached the end of a |
2005 | character set, @code{#f} otherwise. | |
2006 | @end deffn | |
2007 | ||
8f85c0c6 | 2008 | @deffn {Scheme Procedure} char-set-fold kons knil cs |
a0e07ba4 NJ |
2009 | Fold the procedure @var{kons} over the character set @var{cs}, |
2010 | initializing it with @var{knil}. | |
2011 | @end deffn | |
2012 | ||
8f85c0c6 NJ |
2013 | @deffn {Scheme Procedure} char-set-unfold p f g seed [base_cs] |
2014 | @deffnx {Scheme Procedure} char-set-unfold! p f g seed base_cs | |
a0e07ba4 NJ |
2015 | This is a fundamental constructor for character sets. |
2016 | @itemize @bullet | |
12991fed | 2017 | @item @var{g} is used to generate a series of ``seed'' values |
a0e07ba4 NJ |
2018 | from the initial seed: @var{seed}, (@var{g} @var{seed}), |
2019 | (@var{g}^2 @var{seed}), (@var{g}^3 @var{seed}), @dots{} | |
2020 | @item @var{p} tells us when to stop -- when it returns true | |
12991fed | 2021 | when applied to one of the seed values. |
a0e07ba4 NJ |
2022 | @item @var{f} maps each seed value to a character. These |
2023 | characters are added to the base character set @var{base_cs} to | |
2024 | form the result; @var{base_cs} defaults to the empty set. | |
2025 | @end itemize | |
2026 | ||
2027 | @code{char-set-unfold!} is the side-effecting variant. | |
2028 | @end deffn | |
2029 | ||
8f85c0c6 | 2030 | @deffn {Scheme Procedure} char-set-for-each proc cs |
a0e07ba4 NJ |
2031 | Apply @var{proc} to every character in the character set |
2032 | @var{cs}. The return value is not specified. | |
2033 | @end deffn | |
2034 | ||
8f85c0c6 | 2035 | @deffn {Scheme Procedure} char-set-map proc cs |
a0e07ba4 NJ |
2036 | Map the procedure @var{proc} over every character in @var{cs}. |
2037 | @var{proc} must be a character -> character procedure. | |
2038 | @end deffn | |
2039 | ||
2040 | ||
2041 | @c =================================================================== | |
2042 | ||
2043 | @node SRFI-14 Creating Character Sets | |
2044 | @subsection Creating Character Sets | |
2045 | ||
2046 | New character sets are produced with these procedures. | |
2047 | ||
8f85c0c6 | 2048 | @deffn {Scheme Procedure} char-set-copy cs |
a0e07ba4 NJ |
2049 | Return a newly allocated character set containing all |
2050 | characters in @var{cs}. | |
2051 | @end deffn | |
2052 | ||
8f85c0c6 | 2053 | @deffn {Scheme Procedure} char-set char1 @dots{} |
a0e07ba4 NJ |
2054 | Return a character set containing all given characters. |
2055 | @end deffn | |
2056 | ||
8f85c0c6 NJ |
2057 | @deffn {Scheme Procedure} list->char-set char_list [base_cs] |
2058 | @deffnx {Scheme Procedure} list->char-set! char_list base_cs | |
a0e07ba4 NJ |
2059 | Convert the character list @var{list} to a character set. If |
2060 | the character set @var{base_cs} is given, the character in this | |
2061 | set are also included in the result. | |
2062 | ||
2063 | @code{list->char-set!} is the side-effecting variant. | |
2064 | @end deffn | |
2065 | ||
8f85c0c6 NJ |
2066 | @deffn {Scheme Procedure} string->char-set s [base_cs] |
2067 | @deffnx {Scheme Procedure} string->char-set! s base_cs | |
a0e07ba4 NJ |
2068 | Convert the string @var{str} to a character set. If the |
2069 | character set @var{base_cs} is given, the characters in this | |
2070 | set are also included in the result. | |
2071 | ||
2072 | @code{string->char-set!} is the side-effecting variant. | |
2073 | @end deffn | |
2074 | ||
8f85c0c6 NJ |
2075 | @deffn {Scheme Procedure} char-set-filter pred cs [base_cs] |
2076 | @deffnx {Scheme Procedure} char-set-filter! pred cs base_cs | |
a0e07ba4 NJ |
2077 | Return a character set containing every character from @var{cs} |
2078 | so that it satisfies @var{pred}. If provided, the characters | |
2079 | from @var{base_cs} are added to the result. | |
2080 | ||
2081 | @code{char-set-filter!} is the side-effecting variant. | |
2082 | @end deffn | |
2083 | ||
8f85c0c6 NJ |
2084 | @deffn {Scheme Procedure} ucs-range->char-set lower upper [error? base_cs] |
2085 | @deffnx {Scheme Procedure} uce-range->char-set! lower upper error? base_cs | |
a0e07ba4 NJ |
2086 | Return a character set containing all characters whose |
2087 | character codes lie in the half-open range | |
2088 | [@var{lower},@var{upper}). | |
2089 | ||
2090 | If @var{error} is a true value, an error is signalled if the | |
2091 | specified range contains characters which are not contained in | |
2092 | the implemented character range. If @var{error} is @code{#f}, | |
85a9b4ed | 2093 | these characters are silently left out of the resulting |
a0e07ba4 NJ |
2094 | character set. |
2095 | ||
2096 | The characters in @var{base_cs} are added to the result, if | |
2097 | given. | |
2098 | ||
2099 | @code{ucs-range->char-set!} is the side-effecting variant. | |
2100 | @end deffn | |
2101 | ||
8f85c0c6 | 2102 | @deffn {Scheme Procedure} ->char-set x |
a0e07ba4 NJ |
2103 | Coerce @var{x} into a character set. @var{x} may be a string, a |
2104 | character or a character set. | |
2105 | @end deffn | |
2106 | ||
2107 | ||
2108 | @c =================================================================== | |
2109 | ||
2110 | @node SRFI-14 Querying Character Sets | |
2111 | @subsection Querying Character Sets | |
2112 | ||
2113 | Access the elements and other information of a character set with these | |
2114 | procedures. | |
2115 | ||
8f85c0c6 | 2116 | @deffn {Scheme Procedure} char-set-size cs |
a0e07ba4 NJ |
2117 | Return the number of elements in character set @var{cs}. |
2118 | @end deffn | |
2119 | ||
8f85c0c6 | 2120 | @deffn {Scheme Procedure} char-set-count pred cs |
a0e07ba4 NJ |
2121 | Return the number of the elements int the character set |
2122 | @var{cs} which satisfy the predicate @var{pred}. | |
2123 | @end deffn | |
2124 | ||
8f85c0c6 | 2125 | @deffn {Scheme Procedure} char-set->list cs |
a0e07ba4 NJ |
2126 | Return a list containing the elements of the character set |
2127 | @var{cs}. | |
2128 | @end deffn | |
2129 | ||
8f85c0c6 | 2130 | @deffn {Scheme Procedure} char-set->string cs |
a0e07ba4 NJ |
2131 | Return a string containing the elements of the character set |
2132 | @var{cs}. The order in which the characters are placed in the | |
2133 | string is not defined. | |
2134 | @end deffn | |
2135 | ||
8f85c0c6 | 2136 | @deffn {Scheme Procedure} char-set-contains? cs char |
a0e07ba4 NJ |
2137 | Return @code{#t} iff the character @var{ch} is contained in the |
2138 | character set @var{cs}. | |
2139 | @end deffn | |
2140 | ||
8f85c0c6 | 2141 | @deffn {Scheme Procedure} char-set-every pred cs |
a0e07ba4 NJ |
2142 | Return a true value if every character in the character set |
2143 | @var{cs} satisfies the predicate @var{pred}. | |
2144 | @end deffn | |
2145 | ||
8f85c0c6 | 2146 | @deffn {Scheme Procedure} char-set-any pred cs |
a0e07ba4 NJ |
2147 | Return a true value if any character in the character set |
2148 | @var{cs} satisfies the predicate @var{pred}. | |
2149 | @end deffn | |
2150 | ||
2151 | ||
2152 | @c =================================================================== | |
2153 | ||
2154 | @node SRFI-14 Character-Set Algebra | |
2155 | @subsection Character-Set Algebra | |
2156 | ||
2157 | Character sets can be manipulated with the common set algebra operation, | |
2158 | such as union, complement, intersection etc. All of these procedures | |
2159 | provide side-effecting variants, which modify their character set | |
2160 | argument(s). | |
2161 | ||
8f85c0c6 NJ |
2162 | @deffn {Scheme Procedure} char-set-adjoin cs char1 @dots{} |
2163 | @deffnx {Scheme Procedure} char-set-adjoin! cs char1 @dots{} | |
a0e07ba4 NJ |
2164 | Add all character arguments to the first argument, which must |
2165 | be a character set. | |
2166 | @end deffn | |
2167 | ||
8f85c0c6 NJ |
2168 | @deffn {Scheme Procedure} char-set-delete cs char1 @dots{} |
2169 | @deffnx {Scheme Procedure} char-set-delete! cs char1 @dots{} | |
a0e07ba4 NJ |
2170 | Delete all character arguments from the first argument, which |
2171 | must be a character set. | |
2172 | @end deffn | |
2173 | ||
8f85c0c6 NJ |
2174 | @deffn {Scheme Procedure} char-set-complement cs |
2175 | @deffnx {Scheme Procedure} char-set-complement! cs | |
a0e07ba4 NJ |
2176 | Return the complement of the character set @var{cs}. |
2177 | @end deffn | |
2178 | ||
8f85c0c6 NJ |
2179 | @deffn {Scheme Procedure} char-set-union cs1 @dots{} |
2180 | @deffnx {Scheme Procedure} char-set-union! cs1 @dots{} | |
a0e07ba4 NJ |
2181 | Return the union of all argument character sets. |
2182 | @end deffn | |
2183 | ||
8f85c0c6 NJ |
2184 | @deffn {Scheme Procedure} char-set-intersection cs1 @dots{} |
2185 | @deffnx {Scheme Procedure} char-set-intersection! cs1 @dots{} | |
a0e07ba4 NJ |
2186 | Return the intersection of all argument character sets. |
2187 | @end deffn | |
2188 | ||
8f85c0c6 NJ |
2189 | @deffn {Scheme Procedure} char-set-difference cs1 @dots{} |
2190 | @deffnx {Scheme Procedure} char-set-difference! cs1 @dots{} | |
a0e07ba4 NJ |
2191 | Return the difference of all argument character sets. |
2192 | @end deffn | |
2193 | ||
8f85c0c6 NJ |
2194 | @deffn {Scheme Procedure} char-set-xor cs1 @dots{} |
2195 | @deffnx {Scheme Procedure} char-set-xor! cs1 @dots{} | |
a0e07ba4 NJ |
2196 | Return the exclusive-or of all argument character sets. |
2197 | @end deffn | |
2198 | ||
8f85c0c6 NJ |
2199 | @deffn {Scheme Procedure} char-set-diff+intersection cs1 @dots{} |
2200 | @deffnx {Scheme Procedure} char-set-diff+intersection! cs1 @dots{} | |
a0e07ba4 NJ |
2201 | Return the difference and the intersection of all argument |
2202 | character sets. | |
2203 | @end deffn | |
2204 | ||
2205 | ||
2206 | @c =================================================================== | |
2207 | ||
2208 | @node SRFI-14 Standard Character Sets | |
2209 | @subsection Standard Character Sets | |
2210 | ||
2211 | In order to make the use of the character set data type and procedures | |
2212 | useful, several predefined character set variables exist. | |
2213 | ||
2214 | @defvar char-set:lower-case | |
2215 | All lower-case characters. | |
2216 | @end defvar | |
2217 | ||
2218 | @defvar char-set:upper-case | |
2219 | All upper-case characters. | |
2220 | @end defvar | |
2221 | ||
2222 | @defvar char-set:title-case | |
2223 | This is empty, because ASCII has no titlecase characters. | |
2224 | @end defvar | |
2225 | ||
2226 | @defvar char-set:letter | |
2227 | All letters, e.g. the union of @code{char-set:lower-case} and | |
2228 | @code{char-set:upper-case}. | |
2229 | @end defvar | |
2230 | ||
2231 | @defvar char-set:digit | |
2232 | All digits. | |
2233 | @end defvar | |
2234 | ||
2235 | @defvar char-set:letter+digit | |
2236 | The union of @code{char-set:letter} and @code{char-set:digit}. | |
2237 | @end defvar | |
2238 | ||
2239 | @defvar char-set:graphic | |
2240 | All characters which would put ink on the paper. | |
2241 | @end defvar | |
2242 | ||
2243 | @defvar char-set:printing | |
2244 | The union of @code{char-set:graphic} and @code{char-set:whitespace}. | |
2245 | @end defvar | |
2246 | ||
2247 | @defvar char-set:whitespace | |
2248 | All whitespace characters. | |
2249 | @end defvar | |
2250 | ||
2251 | @defvar char-set:blank | |
2252 | All horizontal whitespace characters, that is @code{#\space} and | |
2253 | @code{#\tab}. | |
2254 | @end defvar | |
2255 | ||
2256 | @defvar char-set:iso-control | |
2257 | The ISO control characters with the codes 0--31 and 127. | |
2258 | @end defvar | |
2259 | ||
2260 | @defvar char-set:punctuation | |
2261 | The characters @code{!"#%&'()*,-./:;?@@[\\]_@{@}} | |
2262 | @end defvar | |
2263 | ||
2264 | @defvar char-set:symbol | |
2265 | The characters @code{$+<=>^`|~}. | |
2266 | @end defvar | |
2267 | ||
2268 | @defvar char-set:hex-digit | |
2269 | The hexadecimal digits @code{0123456789abcdefABCDEF}. | |
2270 | @end defvar | |
2271 | ||
2272 | @defvar char-set:ascii | |
2273 | All ASCII characters. | |
2274 | @end defvar | |
2275 | ||
2276 | @defvar char-set:empty | |
2277 | The empty character set. | |
2278 | @end defvar | |
2279 | ||
2280 | @defvar char-set:full | |
2281 | This character set contains all possible characters. | |
2282 | @end defvar | |
2283 | ||
2284 | @node SRFI-16 | |
2285 | @section SRFI-16 - case-lambda | |
8742c48b | 2286 | @cindex SRFI-16 |
a0e07ba4 NJ |
2287 | |
2288 | @c FIXME::martin: Review me! | |
2289 | ||
8742c48b | 2290 | @findex case-lambda |
a0e07ba4 NJ |
2291 | The syntactic form @code{case-lambda} creates procedures, just like |
2292 | @code{lambda}, but has syntactic extensions for writing procedures of | |
2293 | varying arity easier. | |
2294 | ||
2295 | The syntax of the @code{case-lambda} form is defined in the following | |
2296 | EBNF grammar. | |
2297 | ||
2298 | @example | |
2299 | @group | |
2300 | <case-lambda> | |
2301 | --> (case-lambda <case-lambda-clause>) | |
2302 | <case-lambda-clause> | |
2303 | --> (<formals> <definition-or-command>*) | |
2304 | <formals> | |
2305 | --> (<identifier>*) | |
2306 | | (<identifier>* . <identifier>) | |
2307 | | <identifier> | |
2308 | @end group | |
2309 | @end example | |
2310 | ||
2311 | The value returned by a @code{case-lambda} form is a procedure which | |
2312 | matches the number of actual arguments against the formals in the | |
2313 | various clauses, in order. @dfn{Formals} means a formal argument list | |
2314 | just like with @code{lambda} (@pxref{Lambda}). The first matching clause | |
2315 | is selected, the corresponding values from the actual parameter list are | |
2316 | bound to the variable names in the clauses and the body of the clause is | |
2317 | evaluated. If no clause matches, an error is signalled. | |
2318 | ||
2319 | The following (silly) definition creates a procedure @var{foo} which | |
2320 | acts differently, depending on the number of actual arguments. If one | |
2321 | argument is given, the constant @code{#t} is returned, two arguments are | |
2322 | added and if more arguments are passed, their product is calculated. | |
2323 | ||
2324 | @lisp | |
2325 | (define foo (case-lambda | |
2326 | ((x) #t) | |
2327 | ((x y) (+ x y)) | |
2328 | (z | |
2329 | (apply * z)))) | |
2330 | (foo 'bar) | |
2331 | @result{} | |
2332 | #t | |
2333 | (foo 2 4) | |
2334 | @result{} | |
2335 | 6 | |
2336 | (foo 3 3 3) | |
2337 | @result{} | |
2338 | 27 | |
2339 | (foo) | |
2340 | @result{} | |
2341 | 1 | |
2342 | @end lisp | |
2343 | ||
2344 | The last expression evaluates to 1 because the last clause is matched, | |
2345 | @var{z} is bound to the empty list and the following multiplication, | |
2346 | applied to zero arguments, yields 1. | |
2347 | ||
2348 | ||
2349 | @node SRFI-17 | |
2350 | @section SRFI-17 - Generalized set! | |
8742c48b | 2351 | @cindex SRFI-17 |
a0e07ba4 NJ |
2352 | |
2353 | This is an implementation of SRFI-17: Generalized set! | |
2354 | ||
8742c48b | 2355 | @findex getter-with-setter |
a0e07ba4 NJ |
2356 | It exports the Guile procedure @code{make-procedure-with-setter} under |
2357 | the SRFI name @code{getter-with-setter} and exports the standard | |
2358 | procedures @code{car}, @code{cdr}, @dots{}, @code{cdddr}, | |
2359 | @code{string-ref} and @code{vector-ref} as procedures with setters, as | |
2360 | required by the SRFI. | |
2361 | ||
2362 | SRFI-17 was heavily criticized during its discussion period but it was | |
2363 | finalized anyway. One issue was its concept of globally associating | |
2364 | setter @dfn{properties} with (procedure) values, which is non-Schemy. | |
2365 | For this reason, this implementation chooses not to provide a way to set | |
2366 | the setter of a procedure. In fact, @code{(set! (setter @var{proc}) | |
2367 | @var{setter})} signals an error. The only way to attach a setter to a | |
2368 | procedure is to create a new object (a @dfn{procedure with setter}) via | |
2369 | the @code{getter-with-setter} procedure. This procedure is also | |
2370 | specified in the SRFI. Using it avoids the described problems. | |
2371 | ||
12991fed TTN |
2372 | |
2373 | @node SRFI-19 | |
2374 | @section SRFI-19 - Time/Date Library | |
8742c48b | 2375 | @cindex SRFI-19 |
12991fed | 2376 | |
85600a0f KR |
2377 | This is an implementation of the SRFI-19 time/date library. The |
2378 | functions and variables described here are provided by | |
12991fed TTN |
2379 | |
2380 | @example | |
85600a0f | 2381 | (use-modules (srfi srfi-19)) |
12991fed TTN |
2382 | @end example |
2383 | ||
85600a0f KR |
2384 | @menu |
2385 | * SRFI-19 Introduction:: | |
2386 | * SRFI-19 Time:: | |
2387 | * SRFI-19 Date:: | |
2388 | * SRFI-19 Time/Date conversions:: | |
2389 | * SRFI-19 Date to string:: | |
2390 | * SRFI-19 String to date:: | |
2391 | @end menu | |
12991fed | 2392 | |
85600a0f KR |
2393 | @node SRFI-19 Introduction |
2394 | @subsection SRFI-19 Introduction | |
2395 | ||
2396 | @cindex universal time | |
2397 | @cindex atomic time | |
2398 | @cindex UTC | |
2399 | @cindex TAI | |
2400 | This module implements time and date representations and calculations, | |
2401 | in various time systems, including universal time (UTC) and atomic | |
2402 | time (TAI). | |
2403 | ||
2404 | For those not familiar with these time systems, TAI is based on a | |
2405 | fixed length second derived from oscillations of certain atoms. UTC | |
2406 | differs from TAI by an integral number of seconds, which is increased | |
2407 | or decreased at announced times to keep UTC aligned to a mean solar | |
2408 | day (the orbit and rotation of the earth are not quite constant). | |
2409 | ||
2410 | @cindex leap second | |
2411 | So far, only increases in the TAI | |
2412 | @tex | |
2413 | $\leftrightarrow$ | |
2414 | @end tex | |
2415 | @ifnottex | |
2416 | <-> | |
2417 | @end ifnottex | |
2418 | UTC difference have been needed. Such an increase is a ``leap | |
2419 | second'', an extra second of TAI introduced at the end of a UTC day. | |
2420 | When working entirely within UTC this is never seen, every day simply | |
2421 | has 86400 seconds. But when converting from TAI to a UTC date, an | |
2422 | extra 23:59:60 is present, where normally a day would end at 23:59:59. | |
2423 | Effectively the UTC second from 23:59:59 to 00:00:00 has taken two TAI | |
2424 | seconds. | |
2425 | ||
2426 | @cindex system clock | |
2427 | In the current implementation, the system clock is assumed to be UTC, | |
2428 | and a table of leap seconds in the code converts to TAI. See comments | |
2429 | in @file{srfi-19.scm} for how to update this table. | |
2430 | ||
2431 | @cindex julian day | |
2432 | @cindex modified julian day | |
2433 | Also, for those not familiar with the terminology, a @dfn{Julian Day} | |
2434 | is a real number which is a count of days and fraction of a day, in | |
2435 | UTC, starting from -4713-01-01T12:00:00Z, ie.@: midday Monday 1 Jan | |
2436 | 4713 B.C. And a @dfn{Modified Julian Day} is the same, but starting | |
2437 | from 1858-11-17T00:00:00Z, ie.@: midnight 17 November 1858 UTC. | |
2438 | ||
2439 | @c The SRFI-1 spec says -4714-11-24T12:00:00Z (November 24, -4714 at | |
2440 | @c noon, UTC), but this is incorrect. It looks like it might have | |
2441 | @c arisen from the code incorrectly treating years a multiple of 100 | |
2442 | @c but not 400 prior to 1582 as leap years, where instead the Julian | |
2443 | @c calendar should be used so all multiples of 4 before 1582 are leap | |
2444 | @c years. | |
2445 | ||
2446 | ||
2447 | @node SRFI-19 Time | |
2448 | @subsection SRFI-19 Time | |
2449 | @cindex time | |
2450 | ||
2451 | A @dfn{time} object has type, seconds and nanoseconds fields | |
2452 | representing a point in time starting from some epoch. This is an | |
2453 | arbitrary point in time, not just a time of day. Although times are | |
2454 | represented in nanoseconds, the actual resolution may be lower. | |
2455 | ||
2456 | The following variables hold the possible time types. For instance | |
2457 | @code{(current-time time-process)} would give the current CPU process | |
2458 | time. | |
2459 | ||
2460 | @defvar time-utc | |
2461 | Universal Coordinated Time (UTC). | |
2462 | @cindex UTC | |
2463 | @end defvar | |
12991fed | 2464 | |
85600a0f KR |
2465 | @defvar time-tai |
2466 | International Atomic Time (TAI). | |
2467 | @cindex TAI | |
2468 | @end defvar | |
12991fed | 2469 | |
85600a0f KR |
2470 | @defvar time-monotonic |
2471 | Monotonic time, meaning a monotonically increasing time starting from | |
2472 | an unspecified epoch. | |
12991fed | 2473 | |
85600a0f KR |
2474 | Note that in the current implementation @code{time-monotonic} is the |
2475 | same as @code{time-tai}, and unfortunately is therefore affected by | |
2476 | adjustments to the system clock. Perhaps this will change in the | |
2477 | future. | |
2478 | @end defvar | |
12991fed | 2479 | |
85600a0f KR |
2480 | @defvar time-duration |
2481 | A duration, meaning simply a difference between two times. | |
2482 | @end defvar | |
12991fed | 2483 | |
85600a0f KR |
2484 | @defvar time-process |
2485 | CPU time spent in the current process, starting from when the process | |
2486 | began. | |
2487 | @cindex process time | |
2488 | @end defvar | |
12991fed | 2489 | |
85600a0f KR |
2490 | @defvar time-thread |
2491 | CPU time spent in the current thread. Not currently implemented. | |
2492 | @cindex thread time | |
2493 | @end defvar | |
12991fed | 2494 | |
85600a0f KR |
2495 | @sp 1 |
2496 | @defun time? obj | |
2497 | Return @code{#t} if @var{obj} is a time object, or @code{#f} if not. | |
2498 | @end defun | |
2499 | ||
2500 | @defun make-time type nanoseconds seconds | |
2501 | Create a time object with the given @var{type}, @var{seconds} and | |
2502 | @var{nanoseconds}. | |
2503 | @end defun | |
2504 | ||
2505 | @defun time-type time | |
2506 | @defunx time-nanosecond time | |
2507 | @defunx time-second time | |
2508 | @defunx set-time-type! time type | |
2509 | @defunx set-time-nanosecond! time nsec | |
2510 | @defunx set-time-second! time sec | |
2511 | Get or set the type, seconds or nanoseconds fields of a time object. | |
2512 | ||
2513 | @code{set-time-type!} merely changes the field, it doesn't convert the | |
2514 | time value. For conversions, see @ref{SRFI-19 Time/Date conversions}. | |
2515 | @end defun | |
2516 | ||
2517 | @defun copy-time time | |
2518 | Return a new time object, which is a copy of the given @var{time}. | |
2519 | @end defun | |
2520 | ||
2521 | @defun current-time [type] | |
2522 | Return the current time of the given @var{type}. The default | |
2523 | @var{type} is @code{time-utc}. | |
2524 | ||
2525 | Note that the name @code{current-time} conflicts with the Guile core | |
2526 | @code{current-time} function (@pxref{Time}). Applications wanting to | |
2527 | use both will need to use a different name for one of them. | |
2528 | @end defun | |
2529 | ||
2530 | @defun time-resolution [type] | |
2531 | Return the resolution, in nanoseconds, of the given time @var{type}. | |
2532 | The default @var{type} is @code{time-utc}. | |
2533 | @end defun | |
2534 | ||
2535 | @defun time<=? t1 t2 | |
2536 | @defunx time<? t1 t2 | |
2537 | @defunx time=? t1 t2 | |
2538 | @defunx time>=? t1 t2 | |
2539 | @defunx time>? t1 t2 | |
2540 | Return @code{#t} or @code{#f} according to the respective relation | |
2541 | between time objects @var{t1} and @var{t2}. @var{t1} and @var{t2} | |
2542 | must be the same time type. | |
2543 | @end defun | |
2544 | ||
2545 | @defun time-difference t1 t2 | |
2546 | @defunx time-difference! t1 t2 | |
2547 | Return a time object of type @code{time-duration} representing the | |
2548 | period between @var{t1} and @var{t2}. @var{t1} and @var{t2} must be | |
2549 | the same time type. | |
2550 | ||
2551 | @code{time-difference} returns a new time object, | |
2552 | @code{time-difference!} may modify @var{t1} to form its return. | |
2553 | @end defun | |
2554 | ||
2555 | @defun add-duration time duration | |
2556 | @defunx add-duration! time duration | |
2557 | @defunx subtract-duration time duration | |
2558 | @defunx subtract-duration! time duration | |
2559 | Return a time object which is @var{time} with the given @var{duration} | |
2560 | added or subtracted. @var{duration} must be a time object of type | |
2561 | @code{time-duration}. | |
2562 | ||
2563 | @code{add-duration} and @code{subtract-duration} return a new time | |
2564 | object. @code{add-duration!} and @code{subtract-duration!} may modify | |
2565 | the given @var{time} to form their return. | |
2566 | @end defun | |
2567 | ||
2568 | ||
2569 | @node SRFI-19 Date | |
2570 | @subsection SRFI-19 Date | |
2571 | @cindex date | |
2572 | ||
2573 | A @dfn{date} object represents a date in the Gregorian calendar and a | |
2574 | time of day on that date in some timezone. | |
2575 | ||
2576 | The fields are year, month, day, hour, minute, second, nanoseconds and | |
2577 | timezone. A date object is immutable, its fields can be read but they | |
2578 | cannot be modified once the object is created. | |
2579 | ||
2580 | @defun date? obj | |
2581 | Return @code{#t} if @var{obj} is a date object, or @code{#f} if not. | |
2582 | @end defun | |
2583 | ||
2584 | @defun make-date nsecs seconds minutes hours date month year zone-offset | |
2585 | Create a new date object. | |
2586 | @c | |
2587 | @c FIXME: What can we say about the ranges of the values. The | |
2588 | @c current code looks it doesn't normalize, but expects then in their | |
2589 | @c usual range already. | |
2590 | @c | |
2591 | @end defun | |
2592 | ||
2593 | @defun date-nanosecond date | |
2594 | Nanoseconds, 0 to 999999999. | |
2595 | @end defun | |
2596 | ||
2597 | @defun date-second date | |
2598 | Seconds, 0 to 60. 0 to 59 is the usual range, 60 is for a leap second. | |
2599 | @end defun | |
2600 | ||
2601 | @defun date-minute date | |
2602 | Minutes, 0 to 59. | |
2603 | @end defun | |
2604 | ||
2605 | @defun date-hour date | |
2606 | Hour, 0 to 23. | |
2607 | @end defun | |
2608 | ||
2609 | @defun date-day date | |
2610 | Day of the month, 1 to 31 (or less, according to the month). | |
2611 | @end defun | |
2612 | ||
2613 | @defun date-month date | |
2614 | Month, 1 to 12. | |
2615 | @end defun | |
2616 | ||
2617 | @defun date-year date | |
2618 | Year, eg.@: 2003. | |
2619 | @end defun | |
2620 | ||
2621 | @defun date-zone-offset date | |
2622 | Time zone, an integer number of seconds east of Greenwich. | |
2623 | @end defun | |
2624 | ||
2625 | @defun date-year-day date | |
2626 | Day of the year, starting from 1 for 1st January. | |
2627 | @end defun | |
2628 | ||
2629 | @defun date-week-day date | |
2630 | Day of the week, starting from 0 for Sunday. | |
2631 | @end defun | |
2632 | ||
2633 | @defun date-week-number date dstartw | |
2634 | Week of the year, ignoring a first partial week. @var{dstartw} is the | |
2635 | day of the week which is taken to start a week, 0 for Sunday, 1 for | |
2636 | Monday, etc. | |
2637 | @c | |
2638 | @c FIXME: The spec doesn't say whether numbering starts at 0 or 1. | |
2639 | @c The code looks like it's 0, if that's the correct intention. | |
2640 | @c | |
2641 | @end defun | |
2642 | ||
2643 | @c The SRFI text doesn't actually give the default for tz-offset, but | |
2644 | @c the reference implementation has the local timezone and the | |
2645 | @c conversions functions all specify that, so it should be ok to | |
2646 | @c document it here. | |
2647 | @c | |
2648 | @defun current-date [tz-offset] | |
2649 | Return a date object representing the current date/time UTC. | |
2650 | @var{tz-offset} is seconds east of Greenwich, and defaults to the | |
2651 | local timezone. | |
2652 | @end defun | |
2653 | ||
2654 | @defun current-julian-day | |
2655 | @cindex julian day | |
2656 | Return the current Julian Day. | |
2657 | @end defun | |
2658 | ||
2659 | @defun current-modified-julian-day | |
2660 | @cindex modified julian day | |
2661 | Return the current Modified Julian Day. | |
2662 | @end defun | |
2663 | ||
2664 | ||
2665 | @node SRFI-19 Time/Date conversions | |
2666 | @subsection SRFI-19 Time/Date conversions | |
2667 | ||
2668 | @defun date->julian-day date | |
2669 | @defunx date->modified-julian-day date | |
2670 | @defunx date->time-monotonic date | |
2671 | @defunx date->time-tai date | |
2672 | @defunx date->time-utc date | |
2673 | @end defun | |
2674 | @defun julian-day->date jdn [tz-offset] | |
2675 | @defunx julian-day->time-monotonic jdn | |
2676 | @defunx julian-day->time-tai jdn | |
2677 | @defunx julian-day->time-utc jdn | |
2678 | @end defun | |
2679 | @defun modified-julian-day->date jdn [tz-offset] | |
2680 | @defunx modified-julian-day->time-monotonic jdn | |
2681 | @defunx modified-julian-day->time-tai jdn | |
2682 | @defunx modified-julian-day->time-utc jdn | |
2683 | @end defun | |
2684 | @defun time-monotonic->date time [tz-offset] | |
2685 | @defunx time-monotonic->time-tai time | |
2686 | @defunx time-monotonic->time-tai! time | |
2687 | @defunx time-monotonic->time-utc time | |
2688 | @defunx time-monotonic->time-utc! time | |
2689 | @end defun | |
2690 | @defun time-tai->date time [tz-offset] | |
2691 | @defunx time-tai->julian-day time | |
2692 | @defunx time-tai->modified-julian-day time | |
2693 | @defunx time-tai->time-monotonic time | |
2694 | @defunx time-tai->time-monotonic! time | |
2695 | @defunx time-tai->time-utc time | |
2696 | @defunx time-tai->time-utc! time | |
2697 | @end defun | |
2698 | @defun time-utc->date time [tz-offset] | |
2699 | @defunx time-utc->julian-day time | |
2700 | @defunx time-utc->modified-julian-day time | |
2701 | @defunx time-utc->time-monotonic time | |
2702 | @defunx time-utc->time-monotonic! time | |
2703 | @defunx time-utc->time-tai time | |
2704 | @defunx time-utc->time-tai! time | |
2705 | @sp 1 | |
2706 | Convert between dates, times and days of the respective types. For | |
2707 | instance @code{time-tai->time-utc} accepts a @var{time} object of type | |
2708 | @code{time-tai} and returns an object of type @code{time-utc}. | |
2709 | ||
2710 | For conversions to dates, @var{tz-offset} is seconds east of | |
2711 | Greenwich. The default is the local timezone. | |
2712 | ||
2713 | The @code{!} variants may modify their @var{time} argument to form | |
2714 | their return. The plain functions create a new object. | |
2715 | @end defun | |
2716 | ||
2717 | @node SRFI-19 Date to string | |
2718 | @subsection SRFI-19 Date to string | |
2719 | @cindex date to string | |
2720 | ||
2721 | @defun date->string date [format] | |
2722 | Convert a date to a string under the control of a format. | |
2723 | @var{format} should be a string containing @samp{~} escapes, which | |
2724 | will be expanded as per the following conversion table. The default | |
2725 | @var{format} is @samp{~c}, a locale-dependent date and time. | |
2726 | ||
2727 | Many of these conversion characters are the same as POSIX | |
2728 | @code{strftime} (@pxref{Time}), but there are some extras and some | |
2729 | variations. | |
2730 | ||
2731 | @multitable {MMMM} {MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM} | |
2732 | @item @nicode{~~} @tab literal ~ | |
2733 | @item @nicode{~a} @tab locale abbreviated weekday, eg.@: @samp{Sun} | |
2734 | @item @nicode{~A} @tab locale full weekday, eg.@: @samp{Sunday} | |
2735 | @item @nicode{~b} @tab locale abbreviated month, eg.@: @samp{Jan} | |
2736 | @item @nicode{~B} @tab locale full month, eg.@: @samp{January} | |
2737 | @item @nicode{~c} @tab locale date and time, eg.@: @* | |
2738 | @samp{Fri Jul 14 20:28:42-0400 2000} | |
2739 | @item @nicode{~d} @tab day of month, zero padded, @samp{01} to @samp{31} | |
2740 | ||
2741 | @c Spec says d/m/y, reference implementation says m/d/y. | |
2742 | @c Apparently the reference code was the intention, but would like to | |
2743 | @c see an errata published for the spec before contradicting it here. | |
2744 | @c | |
2745 | @c @item @nicode{~D} @tab date @nicode{~d/~m/~y} | |
2746 | ||
2747 | @item @nicode{~e} @tab day of month, blank padded, @samp{ 1} to @samp{31} | |
2748 | @item @nicode{~f} @tab seconds and fractional seconds, | |
2749 | with locale decimal point, eg.@: @samp{5.2} | |
2750 | @item @nicode{~h} @tab same as @nicode{~b} | |
2751 | @item @nicode{~H} @tab hour, 24-hour clock, zero padded, @samp{00} to @samp{23} | |
2752 | @item @nicode{~I} @tab hour, 12-hour clock, zero padded, @samp{01} to @samp{12} | |
2753 | @item @nicode{~j} @tab day of year, zero padded, @samp{001} to @samp{366} | |
2754 | @item @nicode{~k} @tab hour, 24-hour clock, blank padded, @samp{ 0} to @samp{23} | |
2755 | @item @nicode{~l} @tab hour, 12-hour clock, blank padded, @samp{ 1} to @samp{12} | |
2756 | @item @nicode{~m} @tab month, zero padded, @samp{01} to @samp{12} | |
2757 | @item @nicode{~M} @tab minute, zero padded, @samp{00} to @samp{59} | |
2758 | @item @nicode{~n} @tab newline | |
2759 | @item @nicode{~N} @tab nanosecond, zero padded, @samp{000000000} to @samp{999999999} | |
2760 | @item @nicode{~p} @tab locale AM or PM | |
2761 | @item @nicode{~r} @tab time, 12 hour clock, @samp{~I:~M:~S ~p} | |
2762 | @item @nicode{~s} @tab number of full seconds since ``the epoch'' in UTC | |
2763 | @item @nicode{~S} @tab second, zero padded @samp{00} to @samp{60} @* | |
2764 | (usual limit is 59, 60 is a leap second) | |
2765 | @item @nicode{~t} @tab horizontal tab character | |
2766 | @item @nicode{~T} @tab time, 24 hour clock, @samp{~H:~M:~S} | |
2767 | @item @nicode{~U} @tab week of year, Sunday first day of week, | |
2768 | @samp{00} to @samp{52} | |
2769 | @item @nicode{~V} @tab week of year, Monday first day of week, | |
2770 | @samp{01} to @samp{53} | |
2771 | @item @nicode{~w} @tab day of week, 0 for Sunday, @samp{0} to @samp{6} | |
2772 | @item @nicode{~W} @tab week of year, Monday first day of week, | |
2773 | @samp{00} to @samp{52} | |
2774 | ||
2775 | @c The spec has ~x as an apparent duplicate of ~W, and ~X as a locale | |
2776 | @c date. The reference code has ~x as the locale date and ~X as a | |
2777 | @c locale time. The rule is apparently that the code should be | |
2778 | @c believed, but would like to see an errata for the spec before | |
2779 | @c contradicting it here. | |
2780 | @c | |
2781 | @c @item @nicode{~x} @tab week of year, Monday as first day of week, | |
2782 | @c @samp{00} to @samp{53} | |
2783 | @c @item @nicode{~X} @tab locale date, eg.@: @samp{07/31/00} | |
2784 | ||
2785 | @item @nicode{~y} @tab year, two digits, @samp{00} to @samp{99} | |
2786 | @item @nicode{~Y} @tab year, full, eg.@: @samp{2003} | |
2787 | @item @nicode{~z} @tab time zone, RFC-822 style | |
2788 | @item @nicode{~Z} @tab time zone symbol (not currently implemented) | |
2789 | @item @nicode{~1} @tab ISO-8601 date, @samp{~Y-~m-~d} | |
2790 | @item @nicode{~2} @tab ISO-8601 time+zone, @samp{~k:~M:~S~z} | |
2791 | @item @nicode{~3} @tab ISO-8601 time, @samp{~k:~M:~S} | |
2792 | @item @nicode{~4} @tab ISO-8601 date/time+zone, @samp{~Y-~m-~dT~k:~M:~S~z} | |
2793 | @item @nicode{~5} @tab ISO-8601 date/time, @samp{~Y-~m-~dT~k:~M:~S} | |
2794 | @end multitable | |
2795 | @end defun | |
2796 | ||
2797 | Conversions @samp{~D}, @samp{~x} and @samp{~X} are not currently | |
2798 | described here, since the specification and reference implementation | |
2799 | differ. | |
2800 | ||
2801 | Currently Guile doesn't implement any localizations for the above, all | |
2802 | outputs are in English, and the @samp{~c} conversion is POSIX | |
2803 | @code{ctime} style @samp{~a ~b ~d ~H:~M:~S~z ~Y}. This may change in | |
2804 | the future. | |
2805 | ||
2806 | ||
2807 | @node SRFI-19 String to date | |
2808 | @subsection SRFI-19 String to date | |
2809 | @cindex string to date | |
2810 | ||
2811 | @c FIXME: Can we say what happens when an incomplete date is | |
2812 | @c converted? Ie. fields left as 0, or what? The spec seems to be | |
2813 | @c silent on this. | |
2814 | ||
2815 | @defun string->date input template | |
2816 | Convert an @var{input} string to a date under the control of a | |
2817 | @var{template} string. Return a newly created date object. | |
2818 | ||
2819 | Literal characters in @var{template} must match characters in | |
2820 | @var{input} and @samp{~} escapes must match the input forms described | |
2821 | in the table below. ``Skip to'' means characters up to one of the | |
2822 | given type are ignored, or ``no skip'' for no skipping. ``Read'' is | |
2823 | what's then read, and ``Set'' is the field affected in the date | |
2824 | object. | |
2825 | ||
2826 | For example @samp{~Y} skips input characters until a digit is reached, | |
2827 | at which point it expects a year and stores that to the year field of | |
2828 | the date. | |
2829 | ||
2830 | @multitable {MMMM} {@nicode{char-alphabetic?}} {MMMMMMMMMMMMMMMMMMMMMMMMM} {@nicode{date-zone-offset}} | |
2831 | @item | |
2832 | @tab Skip to | |
2833 | @tab Read | |
2834 | @tab Set | |
2835 | ||
2836 | @item @nicode{~~} | |
2837 | @tab no skip | |
2838 | @tab literal ~ | |
2839 | @tab nothing | |
2840 | ||
2841 | @item @nicode{~a} | |
2842 | @tab @nicode{char-alphabetic?} | |
2843 | @tab locale abbreviated weekday name | |
2844 | @tab nothing | |
2845 | ||
2846 | @item @nicode{~A} | |
2847 | @tab @nicode{char-alphabetic?} | |
2848 | @tab locale full weekday name | |
2849 | @tab nothing | |
2850 | ||
2851 | @c Note that the SRFI spec says that ~b and ~B don't set anything, | |
2852 | @c but that looks like a mistake. The reference implementation sets | |
2853 | @c the month field, which seems sensible and is what we describe | |
2854 | @c here. | |
2855 | ||
2856 | @item @nicode{~b} | |
2857 | @tab @nicode{char-alphabetic?} | |
2858 | @tab locale abbreviated month name | |
2859 | @tab @nicode{date-month} | |
2860 | ||
2861 | @item @nicode{~B} | |
2862 | @tab @nicode{char-alphabetic?} | |
2863 | @tab locale full month name | |
2864 | @tab @nicode{date-month} | |
2865 | ||
2866 | @item @nicode{~d} | |
2867 | @tab @nicode{char-numeric?} | |
2868 | @tab day of month | |
2869 | @tab @nicode{date-day} | |
2870 | ||
2871 | @item @nicode{~e} | |
2872 | @tab no skip | |
2873 | @tab day of month, blank padded | |
2874 | @tab @nicode{date-day} | |
2875 | ||
2876 | @item @nicode{~h} | |
2877 | @tab same as @samp{~b} | |
2878 | ||
2879 | @item @nicode{~H} | |
2880 | @tab @nicode{char-numeric?} | |
2881 | @tab hour | |
2882 | @tab @nicode{date-hour} | |
2883 | ||
2884 | @item @nicode{~k} | |
2885 | @tab no skip | |
2886 | @tab hour, blank padded | |
2887 | @tab @nicode{date-hour} | |
2888 | ||
2889 | @item @nicode{~m} | |
2890 | @tab @nicode{char-numeric?} | |
2891 | @tab month | |
2892 | @tab @nicode{date-month} | |
2893 | ||
2894 | @item @nicode{~M} | |
2895 | @tab @nicode{char-numeric?} | |
2896 | @tab minute | |
2897 | @tab @nicode{date-minute} | |
2898 | ||
2899 | @item @nicode{~S} | |
2900 | @tab @nicode{char-numeric?} | |
2901 | @tab second | |
2902 | @tab @nicode{date-second} | |
2903 | ||
2904 | @item @nicode{~y} | |
2905 | @tab no skip | |
2906 | @tab 2-digit year | |
2907 | @tab @nicode{date-year} within 50 years | |
2908 | ||
2909 | @item @nicode{~Y} | |
2910 | @tab @nicode{char-numeric?} | |
2911 | @tab year | |
2912 | @tab @nicode{date-year} | |
2913 | ||
2914 | @item @nicode{~z} | |
2915 | @tab no skip | |
2916 | @tab time zone | |
2917 | @tab date-zone-offset | |
2918 | @end multitable | |
2919 | ||
2920 | Notice that the weekday matching forms don't affect the date object | |
2921 | returned, instead the weekday will be derived from the day, month and | |
2922 | year. | |
2923 | ||
2924 | Currently Guile doesn't implement any localizations for the above, | |
2925 | month and weekday names are always expected in English. This may | |
2926 | change in the future. | |
2927 | @end defun | |
12991fed | 2928 | |
12991fed TTN |
2929 | |
2930 | @c srfi-modules.texi ends here | |
193239f1 KR |
2931 | |
2932 | @c Local Variables: | |
2933 | @c TeX-master: "guile.texi" | |
2934 | @c End: |