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.
  72
  73 Note that some very old Unix systems don't support the `#!' syntax.
  74
  75 * You can now run Guile without installing it.
  76
  77 Previous versions of the interactive Guile interpreter (`guile')
  78 couldn't start up unless Guile's Scheme library had been installed;
  79 they used the value of the environment variable `SCHEME_LOAD_PATH'
  80 later on in the startup process, but not to find the startup code
  81 itself.  Now Guile uses `SCHEME_LOAD_PATH' in all searches for Scheme
  82 code.
  83
  84 To run Guile without installing it, build it in the normal way, and
  85 then set the environment variable `SCHEME_LOAD_PATH' to a
  86 colon-separated list of directories, including the top-level directory
  87 of the Guile sources.  For example, if you unpacked Guile so that the
  88 full filename of this NEWS file is /home/jimb/guile-1.0b3/NEWS, then
  89 you might say
  90
  91         export SCHEME_LOAD_PATH=/home/jimb/my-scheme:/home/jimb/guile-1.0b3
  92
  93 * Guile's header files should no longer conflict with your system's
  94 header files.
  95
  96 In order to compile code which #included <libguile.h>, previous
  97 versions of Guile required you to add a directory containing all the
  98 Guile header files to your #include path.  This was a problem, since
  99 Guile's header files have names which conflict with many systems'
 100 header files.
 101
 102 Now only <libguile.h> need appear in your #include path; you must
 103 refer to all Guile's other header files as <libguile/mumble.h>.
 104 Guile's installation procedure puts libguile.h in $(includedir), and
 105 the rest in $(includedir)/libguile.
 106
 107 * The compiled-library-path function has been deleted from libguile.
 108
 109 * A variable and two new functions have been added to libguile:
 110
 111 ** The variable %load-path now tells Guile which directories to search
 112 for Scheme code.  Its value is a list of strings, each of which names
 113 a directory.
 114
 115 ** (%search-load-path FILENAME) searches the directories listed in the
 116 value of the %load-path variable for a Scheme file named FILENAME.  If
 117 it finds a match, then it returns its full filename.  Otherwise, it
 118 returns #f.  %search-load-path will not return matches that refer to
 119 directories.
 120
 121 ** (%try-load-path FILENAME :optional CASE-INSENSITIVE-P SHARP)
 122 searches the directories listed in %load-path for a file named
 123 FILENAME, and loads it if it finds it.  If it can't read FILENAME for
 124 any reason, it throws an error.
 125
 126 The arguments CASE-INSENSITIVE-P and SHARP are interpreted as by the
 127 %try-load function.
 128
 129 \f
 130 Older changes:
 131
 132 * Guile no longer includes sophisticated Tcl/Tk support.
 133
 134 The old Tcl/Tk support was unsatisfying to us, because it required the
 135 user to link against the Tcl library, as well as Tk and Guile.  The
 136 interface was also un-lispy, in that it preserved Tcl/Tk's practice of
 137 referring to widgets by names, rather than exporting widgets to Scheme
 138 code as a special datatype.
 139
 140 In the Usenix Tk Developer's Workshop held in July 1996, the Tcl/Tk
 141 maintainers described some very interesting changes in progress to the
 142 Tcl/Tk internals, which would facilitate clean interfaces between lone
 143 Tk and other interpreters --- even for garbage-collected languages
 144 like Scheme.  They expected the new Tk to be publicly available in the
 145 fall of 1996.
 146
 147 Since it seems that Guile might soon have a new, cleaner interface to
 148 lone Tk, and that the old Guile/Tk glue code would probably need to be
 149 completely rewritten, we (Jim Blandy and Richard Stallman) have
 150 decided not to support the old code.  We'll spend the time instead on
 151 a good interface to the newer Tk, as soon as it is available.
 152
 153 Until then, gtcltk-lib provides trivial, low-maintenance functionality.
 154
 155 \f
 156 Copyright information:
 157
 158 Copyright (C) 1996 Free Software Foundation, Inc.
 159
 160    Permission is granted to anyone to make or distribute verbatim copies
 161    of this document as received, in any medium, provided that the
 162    copyright notice and this permission notice are preserved,
 163    thus giving the recipient permission to redistribute in turn.
 164
 165    Permission is granted to distribute modified versions
 166    of this document, or of portions of it,
 167    under the above conditions, provided also that they
 168    carry prominent notices stating who last changed them.
 169