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[bpt/guile.git] / NEWS
1 Guile NEWS --- history of user-visible changes. -*- text -*-
2 Copyright (C) 1996, 1997 Free Software Foundation, Inc.
3 See the end for copying conditions.
4
5 Please send Guile bug reports to bug-guile@gnu.org.
6 \f
7 Changes since Guile 1.2:
8
9 * Changes to the distribution
10
11 ** We renamed the SCHEME_LOAD_PATH environment variable to GUILE_LOAD_PATH.
12 To avoid conflicts, programs should name environment variables after
13 themselves, except when there's a common practice establishing some
14 other convention.
15
16 For now, Guile supports both GUILE_LOAD_PATH and SCHEME_LOAD_PATH,
17 giving the former precedence, and printing a warning message if the
18 latter is set. Guile 1.4 will not recognize SCHEME_LOAD_PATH at all.
19
20 ** The header files related to multi-byte characters have been removed.
21 They were: libguile/extchrs.h and libguile/mbstrings.h. Any C code
22 which referred to these explicitly will probably need to be rewritten,
23 since the support for the variant string types has been removed; see
24 below.
25
26 ** The header files append.h and sequences.h have been removed. These
27 files implemented non-R4RS operations which would encourage
28 non-portable programming style and less easy-to-read code.
29
30 * Changes to the stand-alone interpreter
31
32 ** New procedures have been added to implement a "batch mode":
33
34 *** Function: batch-mode?
35
36 Returns a boolean indicating whether the interpreter is in batch
37 mode.
38
39 *** Function: set-batch-mode?! ARG
40
41 If ARG is true, switches the interpreter to batch mode. The `#f'
42 case has not been implemented.
43
44 ** Guile now provides full command-line editing, when run interactively.
45 To use this feature, you must have the readline library installed.
46 The Guile build process will notice it, and automatically include
47 support for it.
48
49 The readline library is available via anonymous FTP from any GNU
50 mirror site; the canonical location is "ftp://prep.ai.mit.edu/pub/gnu".
51
52 ** the-last-stack is now a fluid.
53
54 * Changes to the procedure for linking libguile with your programs
55
56 ** You can now use the 'build-guile' utility to link against Guile.
57
58 Guile now includes a command-line utility called 'build-guile', which
59 writes to its standard output a list of flags which you must pass to
60 the linker to link against the Guile library. The flags include
61 '-lguile' itself, and any other libraries the Guile library depends
62 upon.
63
64 For example, here is a Makefile rule that builds a program named 'foo'
65 from the object files ${FOO_OBJECTS}, and links them against Guile:
66
67 foo: ${FOO_OBJECTS}
68 ${CC} ${CFLAGS} ${FOO_OBJECTS} `build-guile link` -o foo
69
70 Previous Guile releases recommended that you use autoconf to detect
71 which of a predefined set of libraries were present on your system.
72 It is more robust to use build-guile, since it records exactly which
73 libraries the installed Guile library requires.
74
75
76 * Changes to Scheme functions and syntax
77
78 ** Multi-byte strings have been removed, as have multi-byte and wide
79 ports. We felt that these were the wrong approach to
80 internationalization support.
81
82 ** New function: readline [PROMPT]
83 Read a line from the terminal, and allow the user to edit it,
84 prompting with PROMPT. READLINE provides a large set of Emacs-like
85 editing commands, lets the user recall previously typed lines, and
86 works on almost every kind of terminal, including dumb terminals.
87
88 READLINE assumes that the cursor is at the beginning of the line when
89 it is invoked. Thus, you can't print a prompt yourself, and then call
90 READLINE; you need to package up your prompt as a string, pass it to
91 the function, and let READLINE print the prompt itself. This is
92 because READLINE needs to know the prompt's screen width.
93
94 For Guile to provide this function, you must have the readline library
95 installed on your system.
96
97 See also ADD-HISTORY function.
98
99 ** New function: add-history STRING
100 Add STRING as the most recent line in the history used by the READLINE
101 command. READLINE does not add lines to the history itself; you must
102 call ADD-HISTORY to make previous input available to the user.
103
104 ** macro-eval! is removed. Use local-eval instead.
105
106 ** Some magic has been added to the printer to better handle user
107 written printing routines (like record printers, closure printers).
108
109 The problem is that these user written routines must have access to
110 the current `print-state' to be able to handle fancy things like
111 detection of circular references. These print-states have to be
112 passed to the builtin printing routines (display, write, etc) to
113 properly continue the print chain.
114
115 We didn't want to change all existing print code so that it
116 explicitely passes thru a print state in addition to a port. Instead,
117 we extented the possible values that the builtin printing routines
118 accept as a `port'. In addition to a normal port, they now also take
119 a pair of a normal port and a print-state. Printing will go to the
120 port and the print-state will be used to control the detection of
121 circular references, etc. If the builtin function does not care for a
122 print-state, it is simply ignored.
123
124 User written callbacks are now called with such a pair as their
125 `port', but because every function now accepts this pair as a PORT
126 argument, you don't have to worry about that. In fact, it is probably
127 safest to not check for these pairs.
128
129 However, it is sometimes necessary to continue a print chain on a
130 different port, for example to get a intermediate string
131 representation of the printed value, mangle that string somehow, and
132 then to finally print the mangled string. Use the new function
133
134 inherit-print-state OLD-PORT NEW-PORT
135
136 for this. It constructs a new `port' that prints to NEW-PORT but
137 inherits the print-state of OLD-PORT.
138
139 ** struct-vtable-offset renamed to vtable-offset-user
140
141 ** New constants: vtable-index-layout, vtable-index-vtable, vtable-index-printer
142
143 ** There is now a fourth (optional) argument to make-vtable-vtable and
144 make-struct when constructing new types (vtables). This argument
145 initializes field vtable-index-printer of the vtable.
146
147 ** The detection of circular references has been extended to structs.
148 That is, a structure that -- in the process of being printed -- prints
149 itself does not lead to infinite recursion.
150
151 ** There is now some basic support for fluids. Please read
152 "libguile/fluid.h" to find out more. It is accessible from Scheme with
153 the following functions and macros:
154
155 Function: make-fluid
156
157 Create a new fluid object. Fluids are not special variables or
158 some other extension to the semantics of Scheme, but rather
159 ordinary Scheme objects. You can store them into variables (that
160 are still lexically scoped, of course) or into any other place you
161 like. Every fluid has a initial value of `#f'.
162
163 Function: fluid? OBJ
164
165 Test whether OBJ is a fluid.
166
167 Function: fluid-ref FLUID
168 Function: fluid-set! FLUID VAL
169
170 Access/modify the fluid FLUID. Modifications are only visible
171 within the current dynamic root (that includes threads).
172
173 Function: with-fluids* FLUIDS VALUES THUNK
174
175 FLUIDS is a list of fluids and VALUES a corresponding list of
176 values for these fluids. Before THUNK gets called the values are
177 installed in the fluids and the old values of the fluids are
178 saved in the VALUES list. When the flow of control leaves THUNK
179 or reenters it, the values get swapped again. You might think of
180 this as a `safe-fluid-excursion'. Note that the VALUES list is
181 modified by `with-fluids*'.
182
183 Macro: with-fluids ((FLUID VALUE) ...) FORM ...
184
185 The same as `with-fluids*' but with a different syntax. It looks
186 just like `let', but both FLUID and VALUE are evaluated. Remember,
187 fluids are not special variables but ordinary objects. FLUID
188 should evaluate to a fluid.
189
190 ** Changes to system call interfaces:
191
192 *** close-port, close-input-port and close-output-port now return a
193 boolean instead of an `unspecified' object. #t means that the port
194 was successfully closed, while #f means it was already closed. It is
195 also now possible for these procedures to raise an exception if an
196 error occurs (some errors from write can be delayed until close.)
197
198 *** the first argument to chmod, fcntl, ftell and fseek can now be a
199 file descriptor.
200
201 *** the third argument to fcntl is now optional.
202
203 *** the first argument to chown can now be a file descriptor or a port.
204
205 *** the argument to stat can now be a port.
206
207 *** The following new procedures have been added (most use scsh
208 interfaces):
209
210 *** procedure: close PORT/FD
211 Similar to close-port (*note close-port: Closing Ports.), but also
212 works on file descriptors. A side effect of closing a file
213 descriptor is that any ports using that file descriptor are moved
214 to a different file descriptor and have their revealed counts set
215 to zero.
216
217 *** procedure: port->fdes PORT
218 Returns the integer file descriptor underlying PORT. As a side
219 effect the revealed count of PORT is incremented.
220
221 *** procedure: fdes->ports FDES
222 Returns a list of existing ports which have FDES as an underlying
223 file descriptor, without changing their revealed counts.
224
225 *** procedure: fdes->inport FDES
226 Returns an existing input port which has FDES as its underlying
227 file descriptor, if one exists, and increments its revealed count.
228 Otherwise, returns a new input port with a revealed count of 1.
229
230 *** procedure: fdes->outport FDES
231 Returns an existing output port which has FDES as its underlying
232 file descriptor, if one exists, and increments its revealed count.
233 Otherwise, returns a new output port with a revealed count of 1.
234
235 The next group of procedures perform a `dup2' system call, if NEWFD
236 (an integer) is supplied, otherwise a `dup'. The file descriptor to be
237 duplicated can be supplied as an integer or contained in a port. The
238 type of value returned varies depending on which procedure is used.
239
240 All procedures also have the side effect when performing `dup2' that
241 any ports using NEWFD are moved to a different file descriptor and have
242 their revealed counts set to zero.
243
244 *** procedure: dup->fdes PORT/FD [NEWFD]
245 Returns an integer file descriptor.
246
247 *** procedure: dup->inport PORT/FD [NEWFD]
248 Returns a new input port using the new file descriptor.
249
250 *** procedure: dup->outport PORT/FD [NEWFD]
251 Returns a new output port using the new file descriptor.
252
253 *** procedure: dup PORT/FD [NEWFD]
254 Returns a new port if PORT/FD is a port, with the same mode as the
255 supplied port, otherwise returns an integer file descriptor.
256
257 *** procedure: dup->port PORT/FD MODE [NEWFD]
258 Returns a new port using the new file descriptor. MODE supplies a
259 mode string for the port (*note open-file: File Ports.).
260
261 *** procedure: setenv NAME VALUE
262 Modifies the environment of the current process, which is also the
263 default environment inherited by child processes.
264
265 If VALUE is `#f', then NAME is removed from the environment.
266 Otherwise, the string NAME=VALUE is added to the environment,
267 replacing any existing string with name matching NAME.
268
269 The return value is unspecified.
270
271 *** procedure: truncate-file OBJ SIZE
272 Truncates the file referred to by OBJ to at most SIZE bytes. OBJ
273 can be a string containing a file name or an integer file
274 descriptor or port open for output on the file. The underlying
275 system calls are `truncate' and `ftruncate'.
276
277 The return value is unspecified.
278
279 *** procedure: setvbuf PORT MODE [SIZE]
280 Set the buffering mode for PORT. MODE can be:
281 `_IONBF'
282 non-buffered
283
284 `_IOLBF'
285 line buffered
286
287 `_IOFBF'
288 block buffered, using a newly allocated buffer of SIZE bytes.
289 However if SIZE is zero or unspecified, the port will be made
290 non-buffered.
291
292 This procedure should not be used after I/O has been performed with
293 the port.
294
295 Ports are usually block buffered by default, with a default buffer
296 size. Procedures e.g., *Note open-file: File Ports, which accept a
297 mode string allow `0' to be added to request an unbuffered port.
298
299 *** procedure: fsync PORT/FD
300 Copies any unwritten data for the specified output file descriptor
301 to disk. If PORT/FD is a port, its buffer is flushed before the
302 underlying file descriptor is fsync'd. The return value is
303 unspecified.
304
305 *** procedure: open-fdes PATH FLAGS [MODES]
306 Similar to `open' but returns a file descriptor instead of a port.
307
308 *** procedure: execle PATH ENV [ARG] ...
309 Similar to `execl', but the environment of the new process is
310 specified by ENV, which must be a list of strings as returned by
311 the `environ' procedure.
312
313 This procedure is currently implemented using the `execve' system
314 call, but we call it `execle' because of its Scheme calling
315 interface.
316
317 *** procedure: strerror ERRNO
318 Returns the Unix error message corresponding to ERRNO, an integer.
319
320 *** procedure: primitive-exit [STATUS]
321 Terminate the current process without unwinding the Scheme stack.
322 This is would typically be useful after a fork. The exit status
323 is STATUS if supplied, otherwise zero.
324
325 *** procedure: times
326 Returns an object with information about real and processor time.
327 The following procedures accept such an object as an argument and
328 return a selected component:
329
330 `tms:clock'
331 The current real time, expressed as time units relative to an
332 arbitrary base.
333
334 `tms:utime'
335 The CPU time units used by the calling process.
336
337 `tms:stime'
338 The CPU time units used by the system on behalf of the
339 calling process.
340
341 `tms:cutime'
342 The CPU time units used by terminated child processes of the
343 calling process, whose status has been collected (e.g., using
344 `waitpid').
345
346 `tms:cstime'
347 Similarly, the CPU times units used by the system on behalf of
348 terminated child processes.
349
350 ** Removed: list-length
351 ** Removed: list-append, list-append!
352 ** Removed: list-reverse, list-reverse!
353
354 ** array-map renamed to array-map!
355
356 ** serial-array-map renamed to serial-array-map!
357
358 * Changes to the gh_ interface
359
360 ** Function: void gh_write (SCM x)
361
362 Write the printed representation of the scheme object x to the current
363 output port. Corresponds to the scheme level `write'.
364
365 ** gh_list_length renamed to gh_length.
366
367 ** vector handling routines
368
369 Several major changes. In particular, gh_vector() now resembles
370 (vector ...) (with a caveat -- see manual), and gh_make_vector() now
371 exists and behaves like (make-vector ...). gh_vset() and gh_vref()
372 have been renamed gh_vector_set_x() and gh_vector_ref(). Some missing
373 vector-related gh_ functions have been implemented.
374
375 ** pair and list routines
376
377 Implemented several of the R4RS pair and list functions that were
378 missing.
379
380 ** gh_scm2doubles, gh_doubles2scm, gh_doubles2dvect
381
382 New function. Converts double arrays back and forth between Scheme
383 and C.
384
385 * Changes to the scm_ interface
386
387 ** Function: int scm_internal_select (int fds,
388 SELECT_TYPE *rfds,
389 SELECT_TYPE *wfds,
390 SELECT_TYPE *efds,
391 struct timeval *timeout);
392
393 This is a replacement for the `select' function provided by the OS.
394 It enables I/O blocking and sleeping to happen for one cooperative
395 thread without blocking other threads. It also avoids busy-loops in
396 these situations. It is intended that all I/O blocking and sleeping
397 will finally go through this function. Currently, this function is
398 only available on systems providing `gettimeofday' and `select'.
399
400 ** Function: SCM scm_internal_stack_catch (SCM tag,
401 scm_catch_body_t body,
402 void *body_data,
403 scm_catch_handler_t handler,
404 void *handler_data)
405
406 A new sibling to the other two C level `catch' functions
407 scm_internal_catch and scm_internal_lazy_catch. Use it if you want
408 the stack to be saved automatically into the variable `the-last-stack'
409 (scm_the_last_stack_var) on error. This is necessary if you want to
410 use advanced error reporting, such as calling scm_display_error and
411 scm_display_backtrace. (They both take a stack object as argument.)
412
413 ** Function: SCM scm_spawn_thread (scm_catch_body_t body,
414 void *body_data,
415 scm_catch_handler_t handler,
416 void *handler_data)
417
418 Spawns a new thread. It does a job similar to
419 scm_call_with_new_thread but takes arguments more suitable when
420 spawning threads from application C code.
421
422 ** The hook scm_error_callback has been removed. It was originally
423 intended as a way for the user to install his own error handler. But
424 that method works badly since it intervenes between throw and catch,
425 thereby changing the semantics of expressions like (catch #t ...).
426 The correct way to do it is to use one of the C level catch functions
427 in throw.c: scm_internal_catch/lazy_catch/stack_catch.
428
429 ** Removed functions:
430
431 scm_obj_length, scm_list_length, scm_list_append, scm_list_append_x,
432 scm_list_reverse, scm_list_reverse_x
433
434 ** New macros: SCM_LISTn where n is one of the integers 0-9.
435
436 These can be used for pretty list creation from C. The idea is taken
437 from Erick Gallesio's STk.
438
439 ** scm_array_map renamed to scm_array_map_x
440
441 ** mbstrings are now removed
442
443 This means that the type codes scm_tc7_mb_string and
444 scm_tc7_mb_substring has been removed.
445
446 ** The macros SCM_TYP7D and SCM_TYP7SD has been removed.
447
448 ** The macro SCM_TYP7S has taken the role of the old SCM_TYP7D
449
450 SCM_TYP7S now masks away the bit which distinguishes substrings from
451 strings.
452
453 ** All genio functions changed names and interfaces; new functions are
454 scm_putc, scm_puts, scm_lfwrite, scm_getc, scm_ungetc, and
455 scm_do_read_line.
456
457 \f
458 Changes in Guile 1.2 (released Tuesday, June 24 1997):
459
460 * Changes to the distribution
461
462 ** Nightly snapshots are now available from ftp.red-bean.com.
463 The old server, ftp.cyclic.com, has been relinquished to its rightful
464 owner.
465
466 Nightly snapshots of the Guile development sources are now available via
467 anonymous FTP from ftp.red-bean.com, as /pub/guile/guile-snap.tar.gz.
468
469 Via the web, that's: ftp://ftp.red-bean.com/pub/guile/guile-snap.tar.gz
470 For getit, that's: ftp.red-bean.com:/pub/guile/guile-snap.tar.gz
471
472 ** To run Guile without installing it, the procedure has changed a bit.
473
474 If you used a separate build directory to compile Guile, you'll need
475 to include the build directory in SCHEME_LOAD_PATH, as well as the
476 source directory. See the `INSTALL' file for examples.
477
478 * Changes to the procedure for linking libguile with your programs
479
480 ** The standard Guile load path for Scheme code now includes
481 $(datadir)/guile (usually /usr/local/share/guile). This means that
482 you can install your own Scheme files there, and Guile will find them.
483 (Previous versions of Guile only checked a directory whose name
484 contained the Guile version number, so you had to re-install or move
485 your Scheme sources each time you installed a fresh version of Guile.)
486
487 The load path also includes $(datadir)/guile/site; we recommend
488 putting individual Scheme files there. If you want to install a
489 package with multiple source files, create a directory for them under
490 $(datadir)/guile.
491
492 ** Guile 1.2 will now use the Rx regular expression library, if it is
493 installed on your system. When you are linking libguile into your own
494 programs, this means you will have to link against -lguile, -lqt (if
495 you configured Guile with thread support), and -lrx.
496
497 If you are using autoconf to generate configuration scripts for your
498 application, the following lines should suffice to add the appropriate
499 libraries to your link command:
500
501 ### Find Rx, quickthreads and libguile.
502 AC_CHECK_LIB(rx, main)
503 AC_CHECK_LIB(qt, main)
504 AC_CHECK_LIB(guile, scm_shell)
505
506 The Guile 1.2 distribution does not contain sources for the Rx
507 library, as Guile 1.0 did. If you want to use Rx, you'll need to
508 retrieve it from a GNU FTP site and install it separately.
509
510 * Changes to Scheme functions and syntax
511
512 ** The dynamic linking features of Guile are now enabled by default.
513 You can disable them by giving the `--disable-dynamic-linking' option
514 to configure.
515
516 (dynamic-link FILENAME)
517
518 Find the object file denoted by FILENAME (a string) and link it
519 into the running Guile application. When everything works out,
520 return a Scheme object suitable for representing the linked object
521 file. Otherwise an error is thrown. How object files are
522 searched is system dependent.
523
524 (dynamic-object? VAL)
525
526 Determine whether VAL represents a dynamically linked object file.
527
528 (dynamic-unlink DYNOBJ)
529
530 Unlink the indicated object file from the application. DYNOBJ
531 should be one of the values returned by `dynamic-link'.
532
533 (dynamic-func FUNCTION DYNOBJ)
534
535 Search the C function indicated by FUNCTION (a string or symbol)
536 in DYNOBJ and return some Scheme object that can later be used
537 with `dynamic-call' to actually call this function. Right now,
538 these Scheme objects are formed by casting the address of the
539 function to `long' and converting this number to its Scheme
540 representation.
541
542 (dynamic-call FUNCTION DYNOBJ)
543
544 Call the C function indicated by FUNCTION and DYNOBJ. The
545 function is passed no arguments and its return value is ignored.
546 When FUNCTION is something returned by `dynamic-func', call that
547 function and ignore DYNOBJ. When FUNCTION is a string (or symbol,
548 etc.), look it up in DYNOBJ; this is equivalent to
549
550 (dynamic-call (dynamic-func FUNCTION DYNOBJ) #f)
551
552 Interrupts are deferred while the C function is executing (with
553 SCM_DEFER_INTS/SCM_ALLOW_INTS).
554
555 (dynamic-args-call FUNCTION DYNOBJ ARGS)
556
557 Call the C function indicated by FUNCTION and DYNOBJ, but pass it
558 some arguments and return its return value. The C function is
559 expected to take two arguments and return an `int', just like
560 `main':
561
562 int c_func (int argc, char **argv);
563
564 ARGS must be a list of strings and is converted into an array of
565 `char *'. The array is passed in ARGV and its size in ARGC. The
566 return value is converted to a Scheme number and returned from the
567 call to `dynamic-args-call'.
568
569 When dynamic linking is disabled or not supported on your system,
570 the above functions throw errors, but they are still available.
571
572 Here is a small example that works on GNU/Linux:
573
574 (define libc-obj (dynamic-link "libc.so"))
575 (dynamic-args-call 'rand libc-obj '())
576
577 See the file `libguile/DYNAMIC-LINKING' for additional comments.
578
579 ** The #/ syntax for module names is depreciated, and will be removed
580 in a future version of Guile. Instead of
581
582 #/foo/bar/baz
583
584 instead write
585
586 (foo bar baz)
587
588 The latter syntax is more consistent with existing Lisp practice.
589
590 ** Guile now does fancier printing of structures. Structures are the
591 underlying implementation for records, which in turn are used to
592 implement modules, so all of these object now print differently and in
593 a more informative way.
594
595 The Scheme printer will examine the builtin variable *struct-printer*
596 whenever it needs to print a structure object. When this variable is
597 not `#f' it is deemed to be a procedure and will be applied to the
598 structure object and the output port. When *struct-printer* is `#f'
599 or the procedure return `#f' the structure object will be printed in
600 the boring #<struct 80458270> form.
601
602 This hook is used by some routines in ice-9/boot-9.scm to implement
603 type specific printing routines. Please read the comments there about
604 "printing structs".
605
606 One of the more specific uses of structs are records. The printing
607 procedure that could be passed to MAKE-RECORD-TYPE is now actually
608 called. It should behave like a *struct-printer* procedure (described
609 above).
610
611 ** Guile now supports a new R4RS-compliant syntax for keywords. A
612 token of the form #:NAME, where NAME has the same syntax as a Scheme
613 symbol, is the external representation of the keyword named NAME.
614 Keyword objects print using this syntax as well, so values containing
615 keyword objects can be read back into Guile. When used in an
616 expression, keywords are self-quoting objects.
617
618 Guile suports this read syntax, and uses this print syntax, regardless
619 of the current setting of the `keyword' read option. The `keyword'
620 read option only controls whether Guile recognizes the `:NAME' syntax,
621 which is incompatible with R4RS. (R4RS says such token represent
622 symbols.)
623
624 ** Guile has regular expression support again. Guile 1.0 included
625 functions for matching regular expressions, based on the Rx library.
626 In Guile 1.1, the Guile/Rx interface was removed to simplify the
627 distribution, and thus Guile had no regular expression support. Guile
628 1.2 again supports the most commonly used functions, and supports all
629 of SCSH's regular expression functions.
630
631 If your system does not include a POSIX regular expression library,
632 and you have not linked Guile with a third-party regexp library such as
633 Rx, these functions will not be available. You can tell whether your
634 Guile installation includes regular expression support by checking
635 whether the `*features*' list includes the `regex' symbol.
636
637 *** regexp functions
638
639 By default, Guile supports POSIX extended regular expressions. That
640 means that the characters `(', `)', `+' and `?' are special, and must
641 be escaped if you wish to match the literal characters.
642
643 This regular expression interface was modeled after that implemented
644 by SCSH, the Scheme Shell. It is intended to be upwardly compatible
645 with SCSH regular expressions.
646
647 **** Function: string-match PATTERN STR [START]
648 Compile the string PATTERN into a regular expression and compare
649 it with STR. The optional numeric argument START specifies the
650 position of STR at which to begin matching.
651
652 `string-match' returns a "match structure" which describes what,
653 if anything, was matched by the regular expression. *Note Match
654 Structures::. If STR does not match PATTERN at all,
655 `string-match' returns `#f'.
656
657 Each time `string-match' is called, it must compile its PATTERN
658 argument into a regular expression structure. This operation is
659 expensive, which makes `string-match' inefficient if the same regular
660 expression is used several times (for example, in a loop). For better
661 performance, you can compile a regular expression in advance and then
662 match strings against the compiled regexp.
663
664 **** Function: make-regexp STR [FLAGS]
665 Compile the regular expression described by STR, and return the
666 compiled regexp structure. If STR does not describe a legal
667 regular expression, `make-regexp' throws a
668 `regular-expression-syntax' error.
669
670 FLAGS may be the bitwise-or of one or more of the following:
671
672 **** Constant: regexp/extended
673 Use POSIX Extended Regular Expression syntax when interpreting
674 STR. If not set, POSIX Basic Regular Expression syntax is used.
675 If the FLAGS argument is omitted, we assume regexp/extended.
676
677 **** Constant: regexp/icase
678 Do not differentiate case. Subsequent searches using the
679 returned regular expression will be case insensitive.
680
681 **** Constant: regexp/newline
682 Match-any-character operators don't match a newline.
683
684 A non-matching list ([^...]) not containing a newline matches a
685 newline.
686
687 Match-beginning-of-line operator (^) matches the empty string
688 immediately after a newline, regardless of whether the FLAGS
689 passed to regexp-exec contain regexp/notbol.
690
691 Match-end-of-line operator ($) matches the empty string
692 immediately before a newline, regardless of whether the FLAGS
693 passed to regexp-exec contain regexp/noteol.
694
695 **** Function: regexp-exec REGEXP STR [START [FLAGS]]
696 Match the compiled regular expression REGEXP against `str'. If
697 the optional integer START argument is provided, begin matching
698 from that position in the string. Return a match structure
699 describing the results of the match, or `#f' if no match could be
700 found.
701
702 FLAGS may be the bitwise-or of one or more of the following:
703
704 **** Constant: regexp/notbol
705 The match-beginning-of-line operator always fails to match (but
706 see the compilation flag regexp/newline above) This flag may be
707 used when different portions of a string are passed to
708 regexp-exec and the beginning of the string should not be
709 interpreted as the beginning of the line.
710
711 **** Constant: regexp/noteol
712 The match-end-of-line operator always fails to match (but see the
713 compilation flag regexp/newline above)
714
715 **** Function: regexp? OBJ
716 Return `#t' if OBJ is a compiled regular expression, or `#f'
717 otherwise.
718
719 Regular expressions are commonly used to find patterns in one string
720 and replace them with the contents of another string.
721
722 **** Function: regexp-substitute PORT MATCH [ITEM...]
723 Write to the output port PORT selected contents of the match
724 structure MATCH. Each ITEM specifies what should be written, and
725 may be one of the following arguments:
726
727 * A string. String arguments are written out verbatim.
728
729 * An integer. The submatch with that number is written.
730
731 * The symbol `pre'. The portion of the matched string preceding
732 the regexp match is written.
733
734 * The symbol `post'. The portion of the matched string
735 following the regexp match is written.
736
737 PORT may be `#f', in which case nothing is written; instead,
738 `regexp-substitute' constructs a string from the specified ITEMs
739 and returns that.
740
741 **** Function: regexp-substitute/global PORT REGEXP TARGET [ITEM...]
742 Similar to `regexp-substitute', but can be used to perform global
743 substitutions on STR. Instead of taking a match structure as an
744 argument, `regexp-substitute/global' takes two string arguments: a
745 REGEXP string describing a regular expression, and a TARGET string
746 which should be matched against this regular expression.
747
748 Each ITEM behaves as in REGEXP-SUBSTITUTE, with the following
749 exceptions:
750
751 * A function may be supplied. When this function is called, it
752 will be passed one argument: a match structure for a given
753 regular expression match. It should return a string to be
754 written out to PORT.
755
756 * The `post' symbol causes `regexp-substitute/global' to recurse
757 on the unmatched portion of STR. This *must* be supplied in
758 order to perform global search-and-replace on STR; if it is
759 not present among the ITEMs, then `regexp-substitute/global'
760 will return after processing a single match.
761
762 *** Match Structures
763
764 A "match structure" is the object returned by `string-match' and
765 `regexp-exec'. It describes which portion of a string, if any, matched
766 the given regular expression. Match structures include: a reference to
767 the string that was checked for matches; the starting and ending
768 positions of the regexp match; and, if the regexp included any
769 parenthesized subexpressions, the starting and ending positions of each
770 submatch.
771
772 In each of the regexp match functions described below, the `match'
773 argument must be a match structure returned by a previous call to
774 `string-match' or `regexp-exec'. Most of these functions return some
775 information about the original target string that was matched against a
776 regular expression; we will call that string TARGET for easy reference.
777
778 **** Function: regexp-match? OBJ
779 Return `#t' if OBJ is a match structure returned by a previous
780 call to `regexp-exec', or `#f' otherwise.
781
782 **** Function: match:substring MATCH [N]
783 Return the portion of TARGET matched by subexpression number N.
784 Submatch 0 (the default) represents the entire regexp match. If
785 the regular expression as a whole matched, but the subexpression
786 number N did not match, return `#f'.
787
788 **** Function: match:start MATCH [N]
789 Return the starting position of submatch number N.
790
791 **** Function: match:end MATCH [N]
792 Return the ending position of submatch number N.
793
794 **** Function: match:prefix MATCH
795 Return the unmatched portion of TARGET preceding the regexp match.
796
797 **** Function: match:suffix MATCH
798 Return the unmatched portion of TARGET following the regexp match.
799
800 **** Function: match:count MATCH
801 Return the number of parenthesized subexpressions from MATCH.
802 Note that the entire regular expression match itself counts as a
803 subexpression, and failed submatches are included in the count.
804
805 **** Function: match:string MATCH
806 Return the original TARGET string.
807
808 *** Backslash Escapes
809
810 Sometimes you will want a regexp to match characters like `*' or `$'
811 exactly. For example, to check whether a particular string represents
812 a menu entry from an Info node, it would be useful to match it against
813 a regexp like `^* [^:]*::'. However, this won't work; because the
814 asterisk is a metacharacter, it won't match the `*' at the beginning of
815 the string. In this case, we want to make the first asterisk un-magic.
816
817 You can do this by preceding the metacharacter with a backslash
818 character `\'. (This is also called "quoting" the metacharacter, and
819 is known as a "backslash escape".) When Guile sees a backslash in a
820 regular expression, it considers the following glyph to be an ordinary
821 character, no matter what special meaning it would ordinarily have.
822 Therefore, we can make the above example work by changing the regexp to
823 `^\* [^:]*::'. The `\*' sequence tells the regular expression engine
824 to match only a single asterisk in the target string.
825
826 Since the backslash is itself a metacharacter, you may force a
827 regexp to match a backslash in the target string by preceding the
828 backslash with itself. For example, to find variable references in a
829 TeX program, you might want to find occurrences of the string `\let\'
830 followed by any number of alphabetic characters. The regular expression
831 `\\let\\[A-Za-z]*' would do this: the double backslashes in the regexp
832 each match a single backslash in the target string.
833
834 **** Function: regexp-quote STR
835 Quote each special character found in STR with a backslash, and
836 return the resulting string.
837
838 *Very important:* Using backslash escapes in Guile source code (as
839 in Emacs Lisp or C) can be tricky, because the backslash character has
840 special meaning for the Guile reader. For example, if Guile encounters
841 the character sequence `\n' in the middle of a string while processing
842 Scheme code, it replaces those characters with a newline character.
843 Similarly, the character sequence `\t' is replaced by a horizontal tab.
844 Several of these "escape sequences" are processed by the Guile reader
845 before your code is executed. Unrecognized escape sequences are
846 ignored: if the characters `\*' appear in a string, they will be
847 translated to the single character `*'.
848
849 This translation is obviously undesirable for regular expressions,
850 since we want to be able to include backslashes in a string in order to
851 escape regexp metacharacters. Therefore, to make sure that a backslash
852 is preserved in a string in your Guile program, you must use *two*
853 consecutive backslashes:
854
855 (define Info-menu-entry-pattern (make-regexp "^\\* [^:]*"))
856
857 The string in this example is preprocessed by the Guile reader before
858 any code is executed. The resulting argument to `make-regexp' is the
859 string `^\* [^:]*', which is what we really want.
860
861 This also means that in order to write a regular expression that
862 matches a single backslash character, the regular expression string in
863 the source code must include *four* backslashes. Each consecutive pair
864 of backslashes gets translated by the Guile reader to a single
865 backslash, and the resulting double-backslash is interpreted by the
866 regexp engine as matching a single backslash character. Hence:
867
868 (define tex-variable-pattern (make-regexp "\\\\let\\\\=[A-Za-z]*"))
869
870 The reason for the unwieldiness of this syntax is historical. Both
871 regular expression pattern matchers and Unix string processing systems
872 have traditionally used backslashes with the special meanings described
873 above. The POSIX regular expression specification and ANSI C standard
874 both require these semantics. Attempting to abandon either convention
875 would cause other kinds of compatibility problems, possibly more severe
876 ones. Therefore, without extending the Scheme reader to support
877 strings with different quoting conventions (an ungainly and confusing
878 extension when implemented in other languages), we must adhere to this
879 cumbersome escape syntax.
880
881 * Changes to the gh_ interface
882
883 * Changes to the scm_ interface
884
885 * Changes to system call interfaces:
886
887 ** The value returned by `raise' is now unspecified. It throws an exception
888 if an error occurs.
889
890 *** A new procedure `sigaction' can be used to install signal handlers
891
892 (sigaction signum [action] [flags])
893
894 signum is the signal number, which can be specified using the value
895 of SIGINT etc.
896
897 If action is omitted, sigaction returns a pair: the CAR is the current
898 signal hander, which will be either an integer with the value SIG_DFL
899 (default action) or SIG_IGN (ignore), or the Scheme procedure which
900 handles the signal, or #f if a non-Scheme procedure handles the
901 signal. The CDR contains the current sigaction flags for the handler.
902
903 If action is provided, it is installed as the new handler for signum.
904 action can be a Scheme procedure taking one argument, or the value of
905 SIG_DFL (default action) or SIG_IGN (ignore), or #f to restore
906 whatever signal handler was installed before sigaction was first used.
907 Flags can optionally be specified for the new handler (SA_RESTART is
908 always used if the system provides it, so need not be specified.) The
909 return value is a pair with information about the old handler as
910 described above.
911
912 This interface does not provide access to the "signal blocking"
913 facility. Maybe this is not needed, since the thread support may
914 provide solutions to the problem of consistent access to data
915 structures.
916
917 *** A new procedure `flush-all-ports' is equivalent to running
918 `force-output' on every port open for output.
919
920 ** Guile now provides information on how it was built, via the new
921 global variable, %guile-build-info. This variable records the values
922 of the standard GNU makefile directory variables as an assocation
923 list, mapping variable names (symbols) onto directory paths (strings).
924 For example, to find out where the Guile link libraries were
925 installed, you can say:
926
927 guile -c "(display (assq-ref %guile-build-info 'libdir)) (newline)"
928
929
930 * Changes to the scm_ interface
931
932 ** The new function scm_handle_by_message_noexit is just like the
933 existing scm_handle_by_message function, except that it doesn't call
934 exit to terminate the process. Instead, it prints a message and just
935 returns #f. This might be a more appropriate catch-all handler for
936 new dynamic roots and threads.
937
938 \f
939 Changes in Guile 1.1 (released Friday, May 16 1997):
940
941 * Changes to the distribution.
942
943 The Guile 1.0 distribution has been split up into several smaller
944 pieces:
945 guile-core --- the Guile interpreter itself.
946 guile-tcltk --- the interface between the Guile interpreter and
947 Tcl/Tk; Tcl is an interpreter for a stringy language, and Tk
948 is a toolkit for building graphical user interfaces.
949 guile-rgx-ctax --- the interface between Guile and the Rx regular
950 expression matcher, and the translator for the Ctax
951 programming language. These are packaged together because the
952 Ctax translator uses Rx to parse Ctax source code.
953
954 This NEWS file describes the changes made to guile-core since the 1.0
955 release.
956
957 We no longer distribute the documentation, since it was either out of
958 date, or incomplete. As soon as we have current documentation, we
959 will distribute it.
960
961
962
963 * Changes to the stand-alone interpreter
964
965 ** guile now accepts command-line arguments compatible with SCSH, Olin
966 Shivers' Scheme Shell.
967
968 In general, arguments are evaluated from left to right, but there are
969 exceptions. The following switches stop argument processing, and
970 stash all remaining command-line arguments as the value returned by
971 the (command-line) function.
972 -s SCRIPT load Scheme source code from FILE, and exit
973 -c EXPR evalute Scheme expression EXPR, and exit
974 -- stop scanning arguments; run interactively
975
976 The switches below are processed as they are encountered.
977 -l FILE load Scheme source code from FILE
978 -e FUNCTION after reading script, apply FUNCTION to
979 command line arguments
980 -ds do -s script at this point
981 --emacs enable Emacs protocol (experimental)
982 -h, --help display this help and exit
983 -v, --version display version information and exit
984 \ read arguments from following script lines
985
986 So, for example, here is a Guile script named `ekko' (thanks, Olin)
987 which re-implements the traditional "echo" command:
988
989 #!/usr/local/bin/guile -s
990 !#
991 (define (main args)
992 (map (lambda (arg) (display arg) (display " "))
993 (cdr args))
994 (newline))
995
996 (main (command-line))
997
998 Suppose we invoke this script as follows:
999
1000 ekko a speckled gecko
1001
1002 Through the magic of Unix script processing (triggered by the `#!'
1003 token at the top of the file), /usr/local/bin/guile receives the
1004 following list of command-line arguments:
1005
1006 ("-s" "./ekko" "a" "speckled" "gecko")
1007
1008 Unix inserts the name of the script after the argument specified on
1009 the first line of the file (in this case, "-s"), and then follows that
1010 with the arguments given to the script. Guile loads the script, which
1011 defines the `main' function, and then applies it to the list of
1012 remaining command-line arguments, ("a" "speckled" "gecko").
1013
1014 In Unix, the first line of a script file must take the following form:
1015
1016 #!INTERPRETER ARGUMENT
1017
1018 where INTERPRETER is the absolute filename of the interpreter
1019 executable, and ARGUMENT is a single command-line argument to pass to
1020 the interpreter.
1021
1022 You may only pass one argument to the interpreter, and its length is
1023 limited. These restrictions can be annoying to work around, so Guile
1024 provides a general mechanism (borrowed from, and compatible with,
1025 SCSH) for circumventing them.
1026
1027 If the ARGUMENT in a Guile script is a single backslash character,
1028 `\', Guile will open the script file, parse arguments from its second
1029 and subsequent lines, and replace the `\' with them. So, for example,
1030 here is another implementation of the `ekko' script:
1031
1032 #!/usr/local/bin/guile \
1033 -e main -s
1034 !#
1035 (define (main args)
1036 (for-each (lambda (arg) (display arg) (display " "))
1037 (cdr args))
1038 (newline))
1039
1040 If the user invokes this script as follows:
1041
1042 ekko a speckled gecko
1043
1044 Unix expands this into
1045
1046 /usr/local/bin/guile \ ekko a speckled gecko
1047
1048 When Guile sees the `\' argument, it replaces it with the arguments
1049 read from the second line of the script, producing:
1050
1051 /usr/local/bin/guile -e main -s ekko a speckled gecko
1052
1053 This tells Guile to load the `ekko' script, and apply the function
1054 `main' to the argument list ("a" "speckled" "gecko").
1055
1056 Here is how Guile parses the command-line arguments:
1057 - Each space character terminates an argument. This means that two
1058 spaces in a row introduce an empty-string argument.
1059 - The tab character is not permitted (unless you quote it with the
1060 backslash character, as described below), to avoid confusion.
1061 - The newline character terminates the sequence of arguments, and will
1062 also terminate a final non-empty argument. (However, a newline
1063 following a space will not introduce a final empty-string argument;
1064 it only terminates the argument list.)
1065 - The backslash character is the escape character. It escapes
1066 backslash, space, tab, and newline. The ANSI C escape sequences
1067 like \n and \t are also supported. These produce argument
1068 constituents; the two-character combination \n doesn't act like a
1069 terminating newline. The escape sequence \NNN for exactly three
1070 octal digits reads as the character whose ASCII code is NNN. As
1071 above, characters produced this way are argument constituents.
1072 Backslash followed by other characters is not allowed.
1073
1074 * Changes to the procedure for linking libguile with your programs
1075
1076 ** Guile now builds and installs a shared guile library, if your
1077 system support shared libraries. (It still builds a static library on
1078 all systems.) Guile automatically detects whether your system
1079 supports shared libraries. To prevent Guile from buildisg shared
1080 libraries, pass the `--disable-shared' flag to the configure script.
1081
1082 Guile takes longer to compile when it builds shared libraries, because
1083 it must compile every file twice --- once to produce position-
1084 independent object code, and once to produce normal object code.
1085
1086 ** The libthreads library has been merged into libguile.
1087
1088 To link a program against Guile, you now need only link against
1089 -lguile and -lqt; -lthreads is no longer needed. If you are using
1090 autoconf to generate configuration scripts for your application, the
1091 following lines should suffice to add the appropriate libraries to
1092 your link command:
1093
1094 ### Find quickthreads and libguile.
1095 AC_CHECK_LIB(qt, main)
1096 AC_CHECK_LIB(guile, scm_shell)
1097
1098 * Changes to Scheme functions
1099
1100 ** Guile Scheme's special syntax for keyword objects is now optional,
1101 and disabled by default.
1102
1103 The syntax variation from R4RS made it difficult to port some
1104 interesting packages to Guile. The routines which accepted keyword
1105 arguments (mostly in the module system) have been modified to also
1106 accept symbols whose names begin with `:'.
1107
1108 To change the keyword syntax, you must first import the (ice-9 debug)
1109 module:
1110 (use-modules (ice-9 debug))
1111
1112 Then you can enable the keyword syntax as follows:
1113 (read-set! keywords 'prefix)
1114
1115 To disable keyword syntax, do this:
1116 (read-set! keywords #f)
1117
1118 ** Many more primitive functions accept shared substrings as
1119 arguments. In the past, these functions required normal, mutable
1120 strings as arguments, although they never made use of this
1121 restriction.
1122
1123 ** The uniform array functions now operate on byte vectors. These
1124 functions are `array-fill!', `serial-array-copy!', `array-copy!',
1125 `serial-array-map', `array-map', `array-for-each', and
1126 `array-index-map!'.
1127
1128 ** The new functions `trace' and `untrace' implement simple debugging
1129 support for Scheme functions.
1130
1131 The `trace' function accepts any number of procedures as arguments,
1132 and tells the Guile interpreter to display each procedure's name and
1133 arguments each time the procedure is invoked. When invoked with no
1134 arguments, `trace' returns the list of procedures currently being
1135 traced.
1136
1137 The `untrace' function accepts any number of procedures as arguments,
1138 and tells the Guile interpreter not to trace them any more. When
1139 invoked with no arguments, `untrace' untraces all curretly traced
1140 procedures.
1141
1142 The tracing in Guile has an advantage over most other systems: we
1143 don't create new procedure objects, but mark the procedure objects
1144 themselves. This means that anonymous and internal procedures can be
1145 traced.
1146
1147 ** The function `assert-repl-prompt' has been renamed to
1148 `set-repl-prompt!'. It takes one argument, PROMPT.
1149 - If PROMPT is #f, the Guile read-eval-print loop will not prompt.
1150 - If PROMPT is a string, we use it as a prompt.
1151 - If PROMPT is a procedure accepting no arguments, we call it, and
1152 display the result as a prompt.
1153 - Otherwise, we display "> ".
1154
1155 ** The new function `eval-string' reads Scheme expressions from a
1156 string and evaluates them, returning the value of the last expression
1157 in the string. If the string contains no expressions, it returns an
1158 unspecified value.
1159
1160 ** The new function `thunk?' returns true iff its argument is a
1161 procedure of zero arguments.
1162
1163 ** `defined?' is now a builtin function, instead of syntax. This
1164 means that its argument should be quoted. It returns #t iff its
1165 argument is bound in the current module.
1166
1167 ** The new syntax `use-modules' allows you to add new modules to your
1168 environment without re-typing a complete `define-module' form. It
1169 accepts any number of module names as arguments, and imports their
1170 public bindings into the current module.
1171
1172 ** The new function (module-defined? NAME MODULE) returns true iff
1173 NAME, a symbol, is defined in MODULE, a module object.
1174
1175 ** The new function `builtin-bindings' creates and returns a hash
1176 table containing copies of all the root module's bindings.
1177
1178 ** The new function `builtin-weak-bindings' does the same as
1179 `builtin-bindings', but creates a doubly-weak hash table.
1180
1181 ** The `equal?' function now considers variable objects to be
1182 equivalent if they have the same name and the same value.
1183
1184 ** The new function `command-line' returns the command-line arguments
1185 given to Guile, as a list of strings.
1186
1187 When using guile as a script interpreter, `command-line' returns the
1188 script's arguments; those processed by the interpreter (like `-s' or
1189 `-c') are omitted. (In other words, you get the normal, expected
1190 behavior.) Any application that uses scm_shell to process its
1191 command-line arguments gets this behavior as well.
1192
1193 ** The new function `load-user-init' looks for a file called `.guile'
1194 in the user's home directory, and loads it if it exists. This is
1195 mostly for use by the code generated by scm_compile_shell_switches,
1196 but we thought it might also be useful in other circumstances.
1197
1198 ** The new function `log10' returns the base-10 logarithm of its
1199 argument.
1200
1201 ** Changes to I/O functions
1202
1203 *** The functions `read', `primitive-load', `read-and-eval!', and
1204 `primitive-load-path' no longer take optional arguments controlling
1205 case insensitivity and a `#' parser.
1206
1207 Case sensitivity is now controlled by a read option called
1208 `case-insensitive'. The user can add new `#' syntaxes with the
1209 `read-hash-extend' function (see below).
1210
1211 *** The new function `read-hash-extend' allows the user to change the
1212 syntax of Guile Scheme in a somewhat controlled way.
1213
1214 (read-hash-extend CHAR PROC)
1215 When parsing S-expressions, if we read a `#' character followed by
1216 the character CHAR, use PROC to parse an object from the stream.
1217 If PROC is #f, remove any parsing procedure registered for CHAR.
1218
1219 The reader applies PROC to two arguments: CHAR and an input port.
1220
1221 *** The new functions read-delimited and read-delimited! provide a
1222 general mechanism for doing delimited input on streams.
1223
1224 (read-delimited DELIMS [PORT HANDLE-DELIM])
1225 Read until we encounter one of the characters in DELIMS (a string),
1226 or end-of-file. PORT is the input port to read from; it defaults to
1227 the current input port. The HANDLE-DELIM parameter determines how
1228 the terminating character is handled; it should be one of the
1229 following symbols:
1230
1231 'trim omit delimiter from result
1232 'peek leave delimiter character in input stream
1233 'concat append delimiter character to returned value
1234 'split return a pair: (RESULT . TERMINATOR)
1235
1236 HANDLE-DELIM defaults to 'peek.
1237
1238 (read-delimited! DELIMS BUF [PORT HANDLE-DELIM START END])
1239 A side-effecting variant of `read-delimited'.
1240
1241 The data is written into the string BUF at the indices in the
1242 half-open interval [START, END); the default interval is the whole
1243 string: START = 0 and END = (string-length BUF). The values of
1244 START and END must specify a well-defined interval in BUF, i.e.
1245 0 <= START <= END <= (string-length BUF).
1246
1247 It returns NBYTES, the number of bytes read. If the buffer filled
1248 up without a delimiter character being found, it returns #f. If the
1249 port is at EOF when the read starts, it returns the EOF object.
1250
1251 If an integer is returned (i.e., the read is successfully terminated
1252 by reading a delimiter character), then the HANDLE-DELIM parameter
1253 determines how to handle the terminating character. It is described
1254 above, and defaults to 'peek.
1255
1256 (The descriptions of these functions were borrowed from the SCSH
1257 manual, by Olin Shivers and Brian Carlstrom.)
1258
1259 *** The `%read-delimited!' function is the primitive used to implement
1260 `read-delimited' and `read-delimited!'.
1261
1262 (%read-delimited! DELIMS BUF GOBBLE? [PORT START END])
1263
1264 This returns a pair of values: (TERMINATOR . NUM-READ).
1265 - TERMINATOR describes why the read was terminated. If it is a
1266 character or the eof object, then that is the value that terminated
1267 the read. If it is #f, the function filled the buffer without finding
1268 a delimiting character.
1269 - NUM-READ is the number of characters read into BUF.
1270
1271 If the read is successfully terminated by reading a delimiter
1272 character, then the gobble? parameter determines what to do with the
1273 terminating character. If true, the character is removed from the
1274 input stream; if false, the character is left in the input stream
1275 where a subsequent read operation will retrieve it. In either case,
1276 the character is also the first value returned by the procedure call.
1277
1278 (The descriptions of this function was borrowed from the SCSH manual,
1279 by Olin Shivers and Brian Carlstrom.)
1280
1281 *** The `read-line' and `read-line!' functions have changed; they now
1282 trim the terminator by default; previously they appended it to the
1283 returned string. For the old behavior, use (read-line PORT 'concat).
1284
1285 *** The functions `uniform-array-read!' and `uniform-array-write!' now
1286 take new optional START and END arguments, specifying the region of
1287 the array to read and write.
1288
1289 *** The `ungetc-char-ready?' function has been removed. We feel it's
1290 inappropriate for an interface to expose implementation details this
1291 way.
1292
1293 ** Changes to the Unix library and system call interface
1294
1295 *** The new fcntl function provides access to the Unix `fcntl' system
1296 call.
1297
1298 (fcntl PORT COMMAND VALUE)
1299 Apply COMMAND to PORT's file descriptor, with VALUE as an argument.
1300 Values for COMMAND are:
1301
1302 F_DUPFD duplicate a file descriptor
1303 F_GETFD read the descriptor's close-on-exec flag
1304 F_SETFD set the descriptor's close-on-exec flag to VALUE
1305 F_GETFL read the descriptor's flags, as set on open
1306 F_SETFL set the descriptor's flags, as set on open to VALUE
1307 F_GETOWN return the process ID of a socket's owner, for SIGIO
1308 F_SETOWN set the process that owns a socket to VALUE, for SIGIO
1309 FD_CLOEXEC not sure what this is
1310
1311 For details, see the documentation for the fcntl system call.
1312
1313 *** The arguments to `select' have changed, for compatibility with
1314 SCSH. The TIMEOUT parameter may now be non-integral, yielding the
1315 expected behavior. The MILLISECONDS parameter has been changed to
1316 MICROSECONDS, to more closely resemble the underlying system call.
1317 The RVEC, WVEC, and EVEC arguments can now be vectors; the type of the
1318 corresponding return set will be the same.
1319
1320 *** The arguments to the `mknod' system call have changed. They are
1321 now:
1322
1323 (mknod PATH TYPE PERMS DEV)
1324 Create a new file (`node') in the file system. PATH is the name of
1325 the file to create. TYPE is the kind of file to create; it should
1326 be 'fifo, 'block-special, or 'char-special. PERMS specifies the
1327 permission bits to give the newly created file. If TYPE is
1328 'block-special or 'char-special, DEV specifies which device the
1329 special file refers to; its interpretation depends on the kind of
1330 special file being created.
1331
1332 *** The `fork' function has been renamed to `primitive-fork', to avoid
1333 clashing with various SCSH forks.
1334
1335 *** The `recv' and `recvfrom' functions have been renamed to `recv!'
1336 and `recvfrom!'. They no longer accept a size for a second argument;
1337 you must pass a string to hold the received value. They no longer
1338 return the buffer. Instead, `recv' returns the length of the message
1339 received, and `recvfrom' returns a pair containing the packet's length
1340 and originating address.
1341
1342 *** The file descriptor datatype has been removed, as have the
1343 `read-fd', `write-fd', `close', `lseek', and `dup' functions.
1344 We plan to replace these functions with a SCSH-compatible interface.
1345
1346 *** The `create' function has been removed; it's just a special case
1347 of `open'.
1348
1349 *** There are new functions to break down process termination status
1350 values. In the descriptions below, STATUS is a value returned by
1351 `waitpid'.
1352
1353 (status:exit-val STATUS)
1354 If the child process exited normally, this function returns the exit
1355 code for the child process (i.e., the value passed to exit, or
1356 returned from main). If the child process did not exit normally,
1357 this function returns #f.
1358
1359 (status:stop-sig STATUS)
1360 If the child process was suspended by a signal, this function
1361 returns the signal that suspended the child. Otherwise, it returns
1362 #f.
1363
1364 (status:term-sig STATUS)
1365 If the child process terminated abnormally, this function returns
1366 the signal that terminated the child. Otherwise, this function
1367 returns false.
1368
1369 POSIX promises that exactly one of these functions will return true on
1370 a valid STATUS value.
1371
1372 These functions are compatible with SCSH.
1373
1374 *** There are new accessors and setters for the broken-out time vectors
1375 returned by `localtime', `gmtime', and that ilk. They are:
1376
1377 Component Accessor Setter
1378 ========================= ============ ============
1379 seconds tm:sec set-tm:sec
1380 minutes tm:min set-tm:min
1381 hours tm:hour set-tm:hour
1382 day of the month tm:mday set-tm:mday
1383 month tm:mon set-tm:mon
1384 year tm:year set-tm:year
1385 day of the week tm:wday set-tm:wday
1386 day in the year tm:yday set-tm:yday
1387 daylight saving time tm:isdst set-tm:isdst
1388 GMT offset, seconds tm:gmtoff set-tm:gmtoff
1389 name of time zone tm:zone set-tm:zone
1390
1391 *** There are new accessors for the vectors returned by `uname',
1392 describing the host system:
1393
1394 Component Accessor
1395 ============================================== ================
1396 name of the operating system implementation utsname:sysname
1397 network name of this machine utsname:nodename
1398 release level of the operating system utsname:release
1399 version level of the operating system utsname:version
1400 machine hardware platform utsname:machine
1401
1402 *** There are new accessors for the vectors returned by `getpw',
1403 `getpwnam', `getpwuid', and `getpwent', describing entries from the
1404 system's user database:
1405
1406 Component Accessor
1407 ====================== =================
1408 user name passwd:name
1409 user password passwd:passwd
1410 user id passwd:uid
1411 group id passwd:gid
1412 real name passwd:gecos
1413 home directory passwd:dir
1414 shell program passwd:shell
1415
1416 *** There are new accessors for the vectors returned by `getgr',
1417 `getgrnam', `getgrgid', and `getgrent', describing entries from the
1418 system's group database:
1419
1420 Component Accessor
1421 ======================= ============
1422 group name group:name
1423 group password group:passwd
1424 group id group:gid
1425 group members group:mem
1426
1427 *** There are new accessors for the vectors returned by `gethost',
1428 `gethostbyaddr', `gethostbyname', and `gethostent', describing
1429 internet hosts:
1430
1431 Component Accessor
1432 ========================= ===============
1433 official name of host hostent:name
1434 alias list hostent:aliases
1435 host address type hostent:addrtype
1436 length of address hostent:length
1437 list of addresses hostent:addr-list
1438
1439 *** There are new accessors for the vectors returned by `getnet',
1440 `getnetbyaddr', `getnetbyname', and `getnetent', describing internet
1441 networks:
1442
1443 Component Accessor
1444 ========================= ===============
1445 official name of net netent:name
1446 alias list netent:aliases
1447 net number type netent:addrtype
1448 net number netent:net
1449
1450 *** There are new accessors for the vectors returned by `getproto',
1451 `getprotobyname', `getprotobynumber', and `getprotoent', describing
1452 internet protocols:
1453
1454 Component Accessor
1455 ========================= ===============
1456 official protocol name protoent:name
1457 alias list protoent:aliases
1458 protocol number protoent:proto
1459
1460 *** There are new accessors for the vectors returned by `getserv',
1461 `getservbyname', `getservbyport', and `getservent', describing
1462 internet protocols:
1463
1464 Component Accessor
1465 ========================= ===============
1466 official service name servent:name
1467 alias list servent:aliases
1468 port number servent:port
1469 protocol to use servent:proto
1470
1471 *** There are new accessors for the sockaddr structures returned by
1472 `accept', `getsockname', `getpeername', `recvfrom!':
1473
1474 Component Accessor
1475 ======================================== ===============
1476 address format (`family') sockaddr:fam
1477 path, for file domain addresses sockaddr:path
1478 address, for internet domain addresses sockaddr:addr
1479 TCP or UDP port, for internet sockaddr:port
1480
1481 *** The `getpwent', `getgrent', `gethostent', `getnetent',
1482 `getprotoent', and `getservent' functions now return #f at the end of
1483 the user database. (They used to throw an exception.)
1484
1485 Note that calling MUMBLEent function is equivalent to calling the
1486 corresponding MUMBLE function with no arguments.
1487
1488 *** The `setpwent', `setgrent', `sethostent', `setnetent',
1489 `setprotoent', and `setservent' routines now take no arguments.
1490
1491 *** The `gethost', `getproto', `getnet', and `getserv' functions now
1492 provide more useful information when they throw an exception.
1493
1494 *** The `lnaof' function has been renamed to `inet-lnaof'.
1495
1496 *** Guile now claims to have the `current-time' feature.
1497
1498 *** The `mktime' function now takes an optional second argument ZONE,
1499 giving the time zone to use for the conversion. ZONE should be a
1500 string, in the same format as expected for the "TZ" environment variable.
1501
1502 *** The `strptime' function now returns a pair (TIME . COUNT), where
1503 TIME is the parsed time as a vector, and COUNT is the number of
1504 characters from the string left unparsed. This function used to
1505 return the remaining characters as a string.
1506
1507 *** The `gettimeofday' function has replaced the old `time+ticks' function.
1508 The return value is now (SECONDS . MICROSECONDS); the fractional
1509 component is no longer expressed in "ticks".
1510
1511 *** The `ticks/sec' constant has been removed, in light of the above change.
1512
1513 * Changes to the gh_ interface
1514
1515 ** gh_eval_str() now returns an SCM object which is the result of the
1516 evaluation
1517
1518 ** gh_scm2str() now copies the Scheme data to a caller-provided C
1519 array
1520
1521 ** gh_scm2newstr() now makes a C array, copies the Scheme data to it,
1522 and returns the array
1523
1524 ** gh_scm2str0() is gone: there is no need to distinguish
1525 null-terminated from non-null-terminated, since gh_scm2newstr() allows
1526 the user to interpret the data both ways.
1527
1528 * Changes to the scm_ interface
1529
1530 ** The new function scm_symbol_value0 provides an easy way to get a
1531 symbol's value from C code:
1532
1533 SCM scm_symbol_value0 (char *NAME)
1534 Return the value of the symbol named by the null-terminated string
1535 NAME in the current module. If the symbol named NAME is unbound in
1536 the current module, return SCM_UNDEFINED.
1537
1538 ** The new function scm_sysintern0 creates new top-level variables,
1539 without assigning them a value.
1540
1541 SCM scm_sysintern0 (char *NAME)
1542 Create a new Scheme top-level variable named NAME. NAME is a
1543 null-terminated string. Return the variable's value cell.
1544
1545 ** The function scm_internal_catch is the guts of catch. It handles
1546 all the mechanics of setting up a catch target, invoking the catch
1547 body, and perhaps invoking the handler if the body does a throw.
1548
1549 The function is designed to be usable from C code, but is general
1550 enough to implement all the semantics Guile Scheme expects from throw.
1551
1552 TAG is the catch tag. Typically, this is a symbol, but this function
1553 doesn't actually care about that.
1554
1555 BODY is a pointer to a C function which runs the body of the catch;
1556 this is the code you can throw from. We call it like this:
1557 BODY (BODY_DATA, JMPBUF)
1558 where:
1559 BODY_DATA is just the BODY_DATA argument we received; we pass it
1560 through to BODY as its first argument. The caller can make
1561 BODY_DATA point to anything useful that BODY might need.
1562 JMPBUF is the Scheme jmpbuf object corresponding to this catch,
1563 which we have just created and initialized.
1564
1565 HANDLER is a pointer to a C function to deal with a throw to TAG,
1566 should one occur. We call it like this:
1567 HANDLER (HANDLER_DATA, THROWN_TAG, THROW_ARGS)
1568 where
1569 HANDLER_DATA is the HANDLER_DATA argument we recevied; it's the
1570 same idea as BODY_DATA above.
1571 THROWN_TAG is the tag that the user threw to; usually this is
1572 TAG, but it could be something else if TAG was #t (i.e., a
1573 catch-all), or the user threw to a jmpbuf.
1574 THROW_ARGS is the list of arguments the user passed to the THROW
1575 function.
1576
1577 BODY_DATA is just a pointer we pass through to BODY. HANDLER_DATA
1578 is just a pointer we pass through to HANDLER. We don't actually
1579 use either of those pointers otherwise ourselves. The idea is
1580 that, if our caller wants to communicate something to BODY or
1581 HANDLER, it can pass a pointer to it as MUMBLE_DATA, which BODY and
1582 HANDLER can then use. Think of it as a way to make BODY and
1583 HANDLER closures, not just functions; MUMBLE_DATA points to the
1584 enclosed variables.
1585
1586 Of course, it's up to the caller to make sure that any data a
1587 MUMBLE_DATA needs is protected from GC. A common way to do this is
1588 to make MUMBLE_DATA a pointer to data stored in an automatic
1589 structure variable; since the collector must scan the stack for
1590 references anyway, this assures that any references in MUMBLE_DATA
1591 will be found.
1592
1593 ** The new function scm_internal_lazy_catch is exactly like
1594 scm_internal_catch, except:
1595
1596 - It does not unwind the stack (this is the major difference).
1597 - If handler returns, its value is returned from the throw.
1598 - BODY always receives #f as its JMPBUF argument (since there's no
1599 jmpbuf associated with a lazy catch, because we don't unwind the
1600 stack.)
1601
1602 ** scm_body_thunk is a new body function you can pass to
1603 scm_internal_catch if you want the body to be like Scheme's `catch'
1604 --- a thunk, or a function of one argument if the tag is #f.
1605
1606 BODY_DATA is a pointer to a scm_body_thunk_data structure, which
1607 contains the Scheme procedure to invoke as the body, and the tag
1608 we're catching. If the tag is #f, then we pass JMPBUF (created by
1609 scm_internal_catch) to the body procedure; otherwise, the body gets
1610 no arguments.
1611
1612 ** scm_handle_by_proc is a new handler function you can pass to
1613 scm_internal_catch if you want the handler to act like Scheme's catch
1614 --- call a procedure with the tag and the throw arguments.
1615
1616 If the user does a throw to this catch, this function runs a handler
1617 procedure written in Scheme. HANDLER_DATA is a pointer to an SCM
1618 variable holding the Scheme procedure object to invoke. It ought to
1619 be a pointer to an automatic variable (i.e., one living on the stack),
1620 or the procedure object should be otherwise protected from GC.
1621
1622 ** scm_handle_by_message is a new handler function to use with
1623 `scm_internal_catch' if you want Guile to print a message and die.
1624 It's useful for dealing with throws to uncaught keys at the top level.
1625
1626 HANDLER_DATA, if non-zero, is assumed to be a char * pointing to a
1627 message header to print; if zero, we use "guile" instead. That
1628 text is followed by a colon, then the message described by ARGS.
1629
1630 ** The return type of scm_boot_guile is now void; the function does
1631 not return a value, and indeed, never returns at all.
1632
1633 ** The new function scm_shell makes it easy for user applications to
1634 process command-line arguments in a way that is compatible with the
1635 stand-alone guile interpreter (which is in turn compatible with SCSH,
1636 the Scheme shell).
1637
1638 To use the scm_shell function, first initialize any guile modules
1639 linked into your application, and then call scm_shell with the values
1640 of ARGC and ARGV your `main' function received. scm_shell will add
1641 any SCSH-style meta-arguments from the top of the script file to the
1642 argument vector, and then process the command-line arguments. This
1643 generally means loading a script file or starting up an interactive
1644 command interpreter. For details, see "Changes to the stand-alone
1645 interpreter" above.
1646
1647 ** The new functions scm_get_meta_args and scm_count_argv help you
1648 implement the SCSH-style meta-argument, `\'.
1649
1650 char **scm_get_meta_args (int ARGC, char **ARGV)
1651 If the second element of ARGV is a string consisting of a single
1652 backslash character (i.e. "\\" in Scheme notation), open the file
1653 named by the following argument, parse arguments from it, and return
1654 the spliced command line. The returned array is terminated by a
1655 null pointer.
1656
1657 For details of argument parsing, see above, under "guile now accepts
1658 command-line arguments compatible with SCSH..."
1659
1660 int scm_count_argv (char **ARGV)
1661 Count the arguments in ARGV, assuming it is terminated by a null
1662 pointer.
1663
1664 For an example of how these functions might be used, see the source
1665 code for the function scm_shell in libguile/script.c.
1666
1667 You will usually want to use scm_shell instead of calling this
1668 function yourself.
1669
1670 ** The new function scm_compile_shell_switches turns an array of
1671 command-line arguments into Scheme code to carry out the actions they
1672 describe. Given ARGC and ARGV, it returns a Scheme expression to
1673 evaluate, and calls scm_set_program_arguments to make any remaining
1674 command-line arguments available to the Scheme code. For example,
1675 given the following arguments:
1676
1677 -e main -s ekko a speckled gecko
1678
1679 scm_set_program_arguments will return the following expression:
1680
1681 (begin (load "ekko") (main (command-line)) (quit))
1682
1683 You will usually want to use scm_shell instead of calling this
1684 function yourself.
1685
1686 ** The function scm_shell_usage prints a usage message appropriate for
1687 an interpreter that uses scm_compile_shell_switches to handle its
1688 command-line arguments.
1689
1690 void scm_shell_usage (int FATAL, char *MESSAGE)
1691 Print a usage message to the standard error output. If MESSAGE is
1692 non-zero, write it before the usage message, followed by a newline.
1693 If FATAL is non-zero, exit the process, using FATAL as the
1694 termination status. (If you want to be compatible with Guile,
1695 always use 1 as the exit status when terminating due to command-line
1696 usage problems.)
1697
1698 You will usually want to use scm_shell instead of calling this
1699 function yourself.
1700
1701 ** scm_eval_0str now returns SCM_UNSPECIFIED if the string contains no
1702 expressions. It used to return SCM_EOL. Earth-shattering.
1703
1704 ** The macros for declaring scheme objects in C code have been
1705 rearranged slightly. They are now:
1706
1707 SCM_SYMBOL (C_NAME, SCHEME_NAME)
1708 Declare a static SCM variable named C_NAME, and initialize it to
1709 point to the Scheme symbol whose name is SCHEME_NAME. C_NAME should
1710 be a C identifier, and SCHEME_NAME should be a C string.
1711
1712 SCM_GLOBAL_SYMBOL (C_NAME, SCHEME_NAME)
1713 Just like SCM_SYMBOL, but make C_NAME globally visible.
1714
1715 SCM_VCELL (C_NAME, SCHEME_NAME)
1716 Create a global variable at the Scheme level named SCHEME_NAME.
1717 Declare a static SCM variable named C_NAME, and initialize it to
1718 point to the Scheme variable's value cell.
1719
1720 SCM_GLOBAL_VCELL (C_NAME, SCHEME_NAME)
1721 Just like SCM_VCELL, but make C_NAME globally visible.
1722
1723 The `guile-snarf' script writes initialization code for these macros
1724 to its standard output, given C source code as input.
1725
1726 The SCM_GLOBAL macro is gone.
1727
1728 ** The scm_read_line and scm_read_line_x functions have been replaced
1729 by Scheme code based on the %read-delimited! procedure (known to C
1730 code as scm_read_delimited_x). See its description above for more
1731 information.
1732
1733 ** The function scm_sys_open has been renamed to scm_open. It now
1734 returns a port instead of an FD object.
1735
1736 * The dynamic linking support has changed. For more information, see
1737 libguile/DYNAMIC-LINKING.
1738
1739 \f
1740 Guile 1.0b3
1741
1742 User-visible changes from Thursday, September 5, 1996 until Guile 1.0
1743 (Sun 5 Jan 1997):
1744
1745 * Changes to the 'guile' program:
1746
1747 ** Guile now loads some new files when it starts up. Guile first
1748 searches the load path for init.scm, and loads it if found. Then, if
1749 Guile is not being used to execute a script, and the user's home
1750 directory contains a file named `.guile', Guile loads that.
1751
1752 ** You can now use Guile as a shell script interpreter.
1753
1754 To paraphrase the SCSH manual:
1755
1756 When Unix tries to execute an executable file whose first two
1757 characters are the `#!', it treats the file not as machine code to
1758 be directly executed by the native processor, but as source code
1759 to be executed by some interpreter. The interpreter to use is
1760 specified immediately after the #! sequence on the first line of
1761 the source file. The kernel reads in the name of the interpreter,
1762 and executes that instead. It passes the interpreter the source
1763 filename as its first argument, with the original arguments
1764 following. Consult the Unix man page for the `exec' system call
1765 for more information.
1766
1767 Now you can use Guile as an interpreter, using a mechanism which is a
1768 compatible subset of that provided by SCSH.
1769
1770 Guile now recognizes a '-s' command line switch, whose argument is the
1771 name of a file of Scheme code to load. It also treats the two
1772 characters `#!' as the start of a comment, terminated by `!#'. Thus,
1773 to make a file of Scheme code directly executable by Unix, insert the
1774 following two lines at the top of the file:
1775
1776 #!/usr/local/bin/guile -s
1777 !#
1778
1779 Guile treats the argument of the `-s' command-line switch as the name
1780 of a file of Scheme code to load, and treats the sequence `#!' as the
1781 start of a block comment, terminated by `!#'.
1782
1783 For example, here's a version of 'echo' written in Scheme:
1784
1785 #!/usr/local/bin/guile -s
1786 !#
1787 (let loop ((args (cdr (program-arguments))))
1788 (if (pair? args)
1789 (begin
1790 (display (car args))
1791 (if (pair? (cdr args))
1792 (display " "))
1793 (loop (cdr args)))))
1794 (newline)
1795
1796 Why does `#!' start a block comment terminated by `!#', instead of the
1797 end of the line? That is the notation SCSH uses, and although we
1798 don't yet support the other SCSH features that motivate that choice,
1799 we would like to be backward-compatible with any existing Guile
1800 scripts once we do. Furthermore, if the path to Guile on your system
1801 is too long for your kernel, you can start the script with this
1802 horrible hack:
1803
1804 #!/bin/sh
1805 exec /really/long/path/to/guile -s "$0" ${1+"$@"}
1806 !#
1807
1808 Note that some very old Unix systems don't support the `#!' syntax.
1809
1810
1811 ** You can now run Guile without installing it.
1812
1813 Previous versions of the interactive Guile interpreter (`guile')
1814 couldn't start up unless Guile's Scheme library had been installed;
1815 they used the value of the environment variable `SCHEME_LOAD_PATH'
1816 later on in the startup process, but not to find the startup code
1817 itself. Now Guile uses `SCHEME_LOAD_PATH' in all searches for Scheme
1818 code.
1819
1820 To run Guile without installing it, build it in the normal way, and
1821 then set the environment variable `SCHEME_LOAD_PATH' to a
1822 colon-separated list of directories, including the top-level directory
1823 of the Guile sources. For example, if you unpacked Guile so that the
1824 full filename of this NEWS file is /home/jimb/guile-1.0b3/NEWS, then
1825 you might say
1826
1827 export SCHEME_LOAD_PATH=/home/jimb/my-scheme:/home/jimb/guile-1.0b3
1828
1829
1830 ** Guile's read-eval-print loop no longer prints #<unspecified>
1831 results. If the user wants to see this, she can evaluate the
1832 expression (assert-repl-print-unspecified #t), perhaps in her startup
1833 file.
1834
1835 ** Guile no longer shows backtraces by default when an error occurs;
1836 however, it does display a message saying how to get one, and how to
1837 request that they be displayed by default. After an error, evaluate
1838 (backtrace)
1839 to see a backtrace, and
1840 (debug-enable 'backtrace)
1841 to see them by default.
1842
1843
1844
1845 * Changes to Guile Scheme:
1846
1847 ** Guile now distinguishes between #f and the empty list.
1848
1849 This is for compatibility with the IEEE standard, the (possibly)
1850 upcoming Revised^5 Report on Scheme, and many extant Scheme
1851 implementations.
1852
1853 Guile used to have #f and '() denote the same object, to make Scheme's
1854 type system more compatible with Emacs Lisp's. However, the change
1855 caused too much trouble for Scheme programmers, and we found another
1856 way to reconcile Emacs Lisp with Scheme that didn't require this.
1857
1858
1859 ** Guile's delq, delv, delete functions, and their destructive
1860 counterparts, delq!, delv!, and delete!, now remove all matching
1861 elements from the list, not just the first. This matches the behavior
1862 of the corresponding Emacs Lisp functions, and (I believe) the Maclisp
1863 functions which inspired them.
1864
1865 I recognize that this change may break code in subtle ways, but it
1866 seems best to make the change before the FSF's first Guile release,
1867 rather than after.
1868
1869
1870 ** The compiled-library-path function has been deleted from libguile.
1871
1872 ** The facilities for loading Scheme source files have changed.
1873
1874 *** The variable %load-path now tells Guile which directories to search
1875 for Scheme code. Its value is a list of strings, each of which names
1876 a directory.
1877
1878 *** The variable %load-extensions now tells Guile which extensions to
1879 try appending to a filename when searching the load path. Its value
1880 is a list of strings. Its default value is ("" ".scm").
1881
1882 *** (%search-load-path FILENAME) searches the directories listed in the
1883 value of the %load-path variable for a Scheme file named FILENAME,
1884 with all the extensions listed in %load-extensions. If it finds a
1885 match, then it returns its full filename. If FILENAME is absolute, it
1886 returns it unchanged. Otherwise, it returns #f.
1887
1888 %search-load-path will not return matches that refer to directories.
1889
1890 *** (primitive-load FILENAME :optional CASE-INSENSITIVE-P SHARP)
1891 uses %seach-load-path to find a file named FILENAME, and loads it if
1892 it finds it. If it can't read FILENAME for any reason, it throws an
1893 error.
1894
1895 The arguments CASE-INSENSITIVE-P and SHARP are interpreted as by the
1896 `read' function.
1897
1898 *** load uses the same searching semantics as primitive-load.
1899
1900 *** The functions %try-load, try-load-with-path, %load, load-with-path,
1901 basic-try-load-with-path, basic-load-with-path, try-load-module-with-
1902 path, and load-module-with-path have been deleted. The functions
1903 above should serve their purposes.
1904
1905 *** If the value of the variable %load-hook is a procedure,
1906 `primitive-load' applies its value to the name of the file being
1907 loaded (without the load path directory name prepended). If its value
1908 is #f, it is ignored. Otherwise, an error occurs.
1909
1910 This is mostly useful for printing load notification messages.
1911
1912
1913 ** The function `eval!' is no longer accessible from the scheme level.
1914 We can't allow operations which introduce glocs into the scheme level,
1915 because Guile's type system can't handle these as data. Use `eval' or
1916 `read-and-eval!' (see below) as replacement.
1917
1918 ** The new function read-and-eval! reads an expression from PORT,
1919 evaluates it, and returns the result. This is more efficient than
1920 simply calling `read' and `eval', since it is not necessary to make a
1921 copy of the expression for the evaluator to munge.
1922
1923 Its optional arguments CASE_INSENSITIVE_P and SHARP are interpreted as
1924 for the `read' function.
1925
1926
1927 ** The function `int?' has been removed; its definition was identical
1928 to that of `integer?'.
1929
1930 ** The functions `<?', `<?', `<=?', `=?', `>?', and `>=?'. Code should
1931 use the R4RS names for these functions.
1932
1933 ** The function object-properties no longer returns the hash handle;
1934 it simply returns the object's property list.
1935
1936 ** Many functions have been changed to throw errors, instead of
1937 returning #f on failure. The point of providing exception handling in
1938 the language is to simplify the logic of user code, but this is less
1939 useful if Guile's primitives don't throw exceptions.
1940
1941 ** The function `fileno' has been renamed from `%fileno'.
1942
1943 ** The function primitive-mode->fdes returns #t or #f now, not 1 or 0.
1944
1945
1946 * Changes to Guile's C interface:
1947
1948 ** The library's initialization procedure has been simplified.
1949 scm_boot_guile now has the prototype:
1950
1951 void scm_boot_guile (int ARGC,
1952 char **ARGV,
1953 void (*main_func) (),
1954 void *closure);
1955
1956 scm_boot_guile calls MAIN_FUNC, passing it CLOSURE, ARGC, and ARGV.
1957 MAIN_FUNC should do all the work of the program (initializing other
1958 packages, reading user input, etc.) before returning. When MAIN_FUNC
1959 returns, call exit (0); this function never returns. If you want some
1960 other exit value, MAIN_FUNC may call exit itself.
1961
1962 scm_boot_guile arranges for program-arguments to return the strings
1963 given by ARGC and ARGV. If MAIN_FUNC modifies ARGC/ARGV, should call
1964 scm_set_program_arguments with the final list, so Scheme code will
1965 know which arguments have been processed.
1966
1967 scm_boot_guile establishes a catch-all catch handler which prints an
1968 error message and exits the process. This means that Guile exits in a
1969 coherent way when system errors occur and the user isn't prepared to
1970 handle it. If the user doesn't like this behavior, they can establish
1971 their own universal catcher in MAIN_FUNC to shadow this one.
1972
1973 Why must the caller do all the real work from MAIN_FUNC? The garbage
1974 collector assumes that all local variables of type SCM will be above
1975 scm_boot_guile's stack frame on the stack. If you try to manipulate
1976 SCM values after this function returns, it's the luck of the draw
1977 whether the GC will be able to find the objects you allocate. So,
1978 scm_boot_guile function exits, rather than returning, to discourage
1979 people from making that mistake.
1980
1981 The IN, OUT, and ERR arguments were removed; there are other
1982 convenient ways to override these when desired.
1983
1984 The RESULT argument was deleted; this function should never return.
1985
1986 The BOOT_CMD argument was deleted; the MAIN_FUNC argument is more
1987 general.
1988
1989
1990 ** Guile's header files should no longer conflict with your system's
1991 header files.
1992
1993 In order to compile code which #included <libguile.h>, previous
1994 versions of Guile required you to add a directory containing all the
1995 Guile header files to your #include path. This was a problem, since
1996 Guile's header files have names which conflict with many systems'
1997 header files.
1998
1999 Now only <libguile.h> need appear in your #include path; you must
2000 refer to all Guile's other header files as <libguile/mumble.h>.
2001 Guile's installation procedure puts libguile.h in $(includedir), and
2002 the rest in $(includedir)/libguile.
2003
2004
2005 ** Two new C functions, scm_protect_object and scm_unprotect_object,
2006 have been added to the Guile library.
2007
2008 scm_protect_object (OBJ) protects OBJ from the garbage collector.
2009 OBJ will not be freed, even if all other references are dropped,
2010 until someone does scm_unprotect_object (OBJ). Both functions
2011 return OBJ.
2012
2013 Note that calls to scm_protect_object do not nest. You can call
2014 scm_protect_object any number of times on a given object, and the
2015 next call to scm_unprotect_object will unprotect it completely.
2016
2017 Basically, scm_protect_object and scm_unprotect_object just
2018 maintain a list of references to things. Since the GC knows about
2019 this list, all objects it mentions stay alive. scm_protect_object
2020 adds its argument to the list; scm_unprotect_object remove its
2021 argument from the list.
2022
2023
2024 ** scm_eval_0str now returns the value of the last expression
2025 evaluated.
2026
2027 ** The new function scm_read_0str reads an s-expression from a
2028 null-terminated string, and returns it.
2029
2030 ** The new function `scm_stdio_to_port' converts a STDIO file pointer
2031 to a Scheme port object.
2032
2033 ** The new function `scm_set_program_arguments' allows C code to set
2034 the value teruturned by the Scheme `program-arguments' function.
2035
2036 \f
2037 Older changes:
2038
2039 * Guile no longer includes sophisticated Tcl/Tk support.
2040
2041 The old Tcl/Tk support was unsatisfying to us, because it required the
2042 user to link against the Tcl library, as well as Tk and Guile. The
2043 interface was also un-lispy, in that it preserved Tcl/Tk's practice of
2044 referring to widgets by names, rather than exporting widgets to Scheme
2045 code as a special datatype.
2046
2047 In the Usenix Tk Developer's Workshop held in July 1996, the Tcl/Tk
2048 maintainers described some very interesting changes in progress to the
2049 Tcl/Tk internals, which would facilitate clean interfaces between lone
2050 Tk and other interpreters --- even for garbage-collected languages
2051 like Scheme. They expected the new Tk to be publicly available in the
2052 fall of 1996.
2053
2054 Since it seems that Guile might soon have a new, cleaner interface to
2055 lone Tk, and that the old Guile/Tk glue code would probably need to be
2056 completely rewritten, we (Jim Blandy and Richard Stallman) have
2057 decided not to support the old code. We'll spend the time instead on
2058 a good interface to the newer Tk, as soon as it is available.
2059
2060 Until then, gtcltk-lib provides trivial, low-maintenance functionality.
2061
2062 \f
2063 Copyright information:
2064
2065 Copyright (C) 1996,1997 Free Software Foundation, Inc.
2066
2067 Permission is granted to anyone to make or distribute verbatim copies
2068 of this document as received, in any medium, provided that the
2069 copyright notice and this permission notice are preserved,
2070 thus giving the recipient permission to redistribute in turn.
2071
2072 Permission is granted to distribute modified versions
2073 of this document, or of portions of it,
2074 under the above conditions, provided also that they
2075 carry prominent notices stating who last changed them.
2076
2077 \f
2078 Local variables:
2079 mode: outline
2080 paragraph-separate: "[ \f]*$"
2081 end:
2082