NEWS

   1 Guile NEWS --- history of user-visible changes.  2 Aug 1996  -*- text -*-
   2 Copyright (C) 1996 Free Software Foundation, Inc.
   3 See the end for copying conditions.
   4
   5 Please send Guile bug reports to bug-guile@prep.ai.mit.edu.
   6 \f
   7 Guile 1.0b3
   8
   9 Changes since Thursday, September 5:
  10
  11
  12 * Guile now distinguishes between #f and the empty list.
  13
  14 This is for compatibility with the IEEE standard, the (possibly)
  15 upcoming Revised^5 Report on Scheme, and many extant Scheme
  16 implementations.
  17
  18 Guile used to have #f and '() denote the same object, to make Scheme's
  19 type system more compatible with Emacs Lisp's.  However, the change
  20 caused too much trouble for Scheme programmers, and we found another
  21 way to reconcile Emacs Lisp with Scheme that didn't require this.
  22
  23 * You can now use Guile as a shell script interpreter.
  24
  25 To paraphrase the SCSH manual:
  26
  27     When Unix tries to execute an executable file whose first two
  28     characters are the `#!', it treats the file not as machine code to
  29     be directly executed by the native processor, but as source code
  30     to be executed by some interpreter.  The interpreter to use is
  31     specified immediately after the #! sequence on the first line of
  32     the source file.  The kernel reads in the name of the interpreter,
  33     and executes that instead.  It passes the interpreter the source
  34     filename as its first argument, with the original arguments
  35     following.  Consult the Unix man page for the `exec' system call
  36     for more information.
  37
  38 Now you can use Guile as an interpreter, using a mechanism which is a
  39 compatible subset of that provided by SCSH.
  40
  41 Guile now recognizes a '-s' command line switch, whose argument is the
  42 name of a file of Scheme code to load.  It also treats the two
  43 characters `#!' as the start of a comment, terminated by `!#'.  Thus,
  44 to make a file of Scheme code directly executable by Unix, insert the
  45 following two lines at the top of the file:
  46
  47 #!/usr/local/bin/guile -s
  48 !#
  49
  50 Guile treats the argument of the `-s' command-line switch as the name
  51 of a file of Scheme code to load, and treats the sequence `#!' as the
  52 start of a block comment, terminated by `!#'.
  53
  54 For example, here's a version of 'echo' written in Scheme:
  55
  56 #!/usr/local/bin/guile -s
  57 !#
  58 (let loop ((args (cdr (program-arguments))))
  59   (if (pair? args)
  60       (begin
  61         (display (car args))
  62         (if (pair? (cdr args))
  63             (display " "))
  64         (loop (cdr args)))))
  65 (newline)
  66
  67 Why does `#!' start a block comment terminated by `!#', instead of the
  68 end of the line?  That is the notation SCSH uses, and although we
  69 don't yet support the other SCSH features that motivate that choice,
  70 we would like to be backward-compatible with any existing Guile
  71 scripts once we do.  Furthermore, if the path to Guile on your system
  72 is too long for your kernel, you can start the script with this
  73 horrible hack:
  74
  75 #!/bin/sh
  76 exec /really/long/path/to/guile -s "$0" ${1+"$@"}
  77 !#
  78
  79 Note that some very old Unix systems don't support the `#!' syntax.
  80
  81 * You can now run Guile without installing it.
  82
  83 Previous versions of the interactive Guile interpreter (`guile')
  84 couldn't start up unless Guile's Scheme library had been installed;
  85 they used the value of the environment variable `SCHEME_LOAD_PATH'
  86 later on in the startup process, but not to find the startup code
  87 itself.  Now Guile uses `SCHEME_LOAD_PATH' in all searches for Scheme
  88 code.
  89
  90 To run Guile without installing it, build it in the normal way, and
  91 then set the environment variable `SCHEME_LOAD_PATH' to a
  92 colon-separated list of directories, including the top-level directory
  93 of the Guile sources.  For example, if you unpacked Guile so that the
  94 full filename of this NEWS file is /home/jimb/guile-1.0b3/NEWS, then
  95 you might say
  96
  97         export SCHEME_LOAD_PATH=/home/jimb/my-scheme:/home/jimb/guile-1.0b3
  98
  99 * Guile's header files should no longer conflict with your system's
 100 header files.
 101
 102 In order to compile code which #included <libguile.h>, previous
 103 versions of Guile required you to add a directory containing all the
 104 Guile header files to your #include path.  This was a problem, since
 105 Guile's header files have names which conflict with many systems'
 106 header files.
 107
 108 Now only <libguile.h> need appear in your #include path; you must
 109 refer to all Guile's other header files as <libguile/mumble.h>.
 110 Guile's installation procedure puts libguile.h in $(includedir), and
 111 the rest in $(includedir)/libguile.
 112
 113 * The compiled-library-path function has been deleted from libguile.
 114
 115 * A variable and two new functions have been added to libguile:
 116
 117 ** The variable %load-path now tells Guile which directories to search
 118 for Scheme code.  Its value is a list of strings, each of which names
 119 a directory.
 120
 121 ** (%search-load-path FILENAME) searches the directories listed in the
 122 value of the %load-path variable for a Scheme file named FILENAME.  If
 123 it finds a match, then it returns its full filename.  Otherwise, it
 124 returns #f.  %search-load-path will not return matches that refer to
 125 directories.
 126
 127 ** (%try-load-path FILENAME :optional CASE-INSENSITIVE-P SHARP)
 128 searches the directories listed in %load-path for a file named
 129 FILENAME, and loads it if it finds it.  If it can't read FILENAME for
 130 any reason, it throws an error.
 131
 132 The arguments CASE-INSENSITIVE-P and SHARP are interpreted as by the
 133 %try-load function.
 134
 135 \f
 136 Older changes:
 137
 138 * Guile no longer includes sophisticated Tcl/Tk support.
 139
 140 The old Tcl/Tk support was unsatisfying to us, because it required the
 141 user to link against the Tcl library, as well as Tk and Guile.  The
 142 interface was also un-lispy, in that it preserved Tcl/Tk's practice of
 143 referring to widgets by names, rather than exporting widgets to Scheme
 144 code as a special datatype.
 145
 146 In the Usenix Tk Developer's Workshop held in July 1996, the Tcl/Tk
 147 maintainers described some very interesting changes in progress to the
 148 Tcl/Tk internals, which would facilitate clean interfaces between lone
 149 Tk and other interpreters --- even for garbage-collected languages
 150 like Scheme.  They expected the new Tk to be publicly available in the
 151 fall of 1996.
 152
 153 Since it seems that Guile might soon have a new, cleaner interface to
 154 lone Tk, and that the old Guile/Tk glue code would probably need to be
 155 completely rewritten, we (Jim Blandy and Richard Stallman) have
 156 decided not to support the old code.  We'll spend the time instead on
 157 a good interface to the newer Tk, as soon as it is available.
 158
 159 Until then, gtcltk-lib provides trivial, low-maintenance functionality.
 160
 161 \f
 162 Copyright information:
 163
 164 Copyright (C) 1996 Free Software Foundation, Inc.
 165
 166    Permission is granted to anyone to make or distribute verbatim copies
 167    of this document as received, in any medium, provided that the
 168    copyright notice and this permission notice are preserved,
 169    thus giving the recipient permission to redistribute in turn.
 170
 171    Permission is granted to distribute modified versions
 172    of this document, or of portions of it,
 173    under the above conditions, provided also that they
 174    carry prominent notices stating who last changed them.
 175