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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 | ||
16f2ebea | 5 | Please send Guile bug reports to bug-guile@prep.ai.mit.edu. |
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6 | \f |
7 | Guile 1.0b3 | |
8 | ||
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9 | Changes since Thursday, September 5: |
10 | ||
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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 | ||
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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 | |
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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 |