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
  24 * You can now use Guile as a shell script interpreter.
  25
  26 To paraphrase the SCSH manual:
  27
  28     When Unix tries to execute an executable file whose first two
  29     characters are the `#!', it treats the file not as machine code to
  30     be directly executed by the native processor, but as source code
  31     to be executed by some interpreter.  The interpreter to use is
  32     specified immediately after the #! sequence on the first line of
  33     the source file.  The kernel reads in the name of the interpreter,
  34     and executes that instead.  It passes the interpreter the source
  35     filename as its first argument, with the original arguments
  36     following.  Consult the Unix man page for the `exec' system call
  37     for more information.
  38
  39 Guile now recognizes a '-s' command line switch, whose argument is the
  40 name of a file of Scheme code to load.  It also treats the two
  41 characters `#!' as the start of a comment, terminated by `!#'.  Thus,
  42 to make a file of Scheme code directly executable by Unix, insert the
  43 following two lines at the top of the file:
  44
  45 #!/usr/local/bin/guile -s
  46 !#
  47
  48 Guile treats the argument of the `-s' command-line switch as the name
  49 of a file of Scheme code to load, and treats the sequence `#!' as the
  50 start of a block comment, terminated by `!#'.
  51
  52 For example, here's a version of 'echo' written in Scheme:
  53
  54 #!/usr/local/bin/guile -s
  55 !#
  56 (let loop ((args (cdr (program-arguments))))
  57   (if (pair? args)
  58       (begin
  59         (display (car args))
  60         (if (pair? (cdr args))
  61             (display " "))
  62         (loop (cdr args)))))
  63 (newline)
  64
  65 Why does `#!' start a block comment terminated by `!#', instead of the
  66 end of the line?  That is the notation SCSH uses, and although we
  67 don't yet support the other SCSH features that motivate that choice,
  68 we would like to be backward-compatible with any existing Guile
  69 scripts once we do.
  70
  71 Note that some very old Unix systems don't support the `#!' syntax.
  72
  73
  74 * You can now run Guile without installing it.
  75
  76 Previous versions of the interactive Guile interpreter (`guile')
  77 couldn't start up unless Guile's Scheme library had been installed;
  78 they used the value of the environment variable `SCHEME_LOAD_PATH'
  79 later on in the startup process, but not to find the startup code
  80 itself.  Now Guile uses `SCHEME_LOAD_PATH' in all searches for Scheme
  81 code.
  82
  83 To run Guile without installing it, build it in the normal way, and
  84 then set the environment variable `SCHEME_LOAD_PATH' to a
  85 colon-separated list of directories, including the top-level directory
  86 of the Guile sources.  For example, if you unpacked Guile so that the
  87 full filename of this NEWS file is /home/jimb/guile-1.0b3/NEWS, then
  88 you might say
  89
  90         export SCHEME_LOAD_PATH=/home/jimb/my-scheme:/home/jimb/guile-1.0b3
  91
  92 * Guile's header files should no longer conflict with your system's
  93 header files.
  94
  95 In order to compile code which #included <libguile.h>, previous
  96 versions of Guile required you to add a directory containing all the
  97 Guile header files to your #include path.  This was a problem, since
  98 Guile's header files have names which conflict with many systems'
  99 header files.
 100
 101 Now only <libguile.h> need appear in your #include path; you must
 102 refer to all Guile's other header files as <libguile/mumble.h>.
 103 Guile's installation procedure puts libguile.h in $(includedir), and
 104 the rest in $(includedir)/libguile.
 105
 106 * The compiled-library-path function has been deleted from libguile.
 107
 108 * A variable and two new functions have been added to libguile:
 109
 110 ** The variable %load-path now tells Guile which directories to search
 111 for Scheme code.  Its value is a list of strings, each of which names
 112 a directory.
 113
 114 ** (%search-load-path FILENAME) searches the directories listed in the
 115 value of the %load-path variable for a Scheme file named FILENAME.  If
 116 it finds a match, then it returns its full filename.  Otherwise, it
 117 returns #f.  %search-load-path will not return matches that refer to
 118 directories.
 119
 120 ** (%try-load-path FILENAME :optional CASE-INSENSITIVE-P SHARP)
 121 searches the directories listed in %load-path for a file named
 122 FILENAME, and loads it if it finds it.  If it can't read FILENAME for
 123 any reason, it throws an error.
 124
 125 The arguments CASE-INSENSITIVE-P and SHARP are interpreted as by the
 126 %try-load function.
 127
 128
 129 \f
 130 This is the beginning of recorded history.
 131
 132 \f
 133 Copyright information:
 134
 135 Copyright (C) 1996 Free Software Foundation, Inc.
 136
 137    Permission is granted to anyone to make or distribute verbatim copies
 138    of this document as received, in any medium, provided that the
 139    copyright notice and this permission notice are preserved,
 140    thus giving the recipient permission to redistribute in turn.
 141
 142    Permission is granted to distribute modified versions
 143    of this document, or of portions of it,
 144    under the above conditions, provided also that they
 145    carry prominent notices stating who last changed them.
 146