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1 @c -*-texinfo-*-
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2 @c This is part of the XEmacs Lisp Reference Manual.
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3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
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4 @c See the file lispref.texi for copying conditions.
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5 @setfilename ../../info/intro.info
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6
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7 @node Copying, Introduction, Top, Top
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8 @unnumbered GNU GENERAL PUBLIC LICENSE
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9 @center Version 2, June 1991
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10
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11 @display
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12 Copyright @copyright{} 1989, 1991 Free Software Foundation, Inc.
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13 675 Mass Ave, Cambridge, MA 02139, USA
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14
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15 Everyone is permitted to copy and distribute verbatim copies
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16 of this license document, but changing it is not allowed.
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17 @end display
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18
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19 @unnumberedsec Preamble
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20
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21 The licenses for most software are designed to take away your
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22 freedom to share and change it. By contrast, the GNU General Public
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23 License is intended to guarantee your freedom to share and change free
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24 software---to make sure the software is free for all its users. This
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25 General Public License applies to most of the Free Software
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26 Foundation's software and to any other program whose authors commit to
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27 using it. (Some other Free Software Foundation software is covered by
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28 the GNU Library General Public License instead.) You can apply it to
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29 your programs, too.
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30
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31 When we speak of free software, we are referring to freedom, not
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32 price. Our General Public Licenses are designed to make sure that you
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33 have the freedom to distribute copies of free software (and charge for
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34 this service if you wish), that you receive source code or can get it
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35 if you want it, that you can change the software or use pieces of it
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36 in new free programs; and that you know you can do these things.
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37
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38 To protect your rights, we need to make restrictions that forbid
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39 anyone to deny you these rights or to ask you to surrender the rights.
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40 These restrictions translate to certain responsibilities for you if you
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41 distribute copies of the software, or if you modify it.
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42
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43 For example, if you distribute copies of such a program, whether
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44 gratis or for a fee, you must give the recipients all the rights that
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45 you have. You must make sure that they, too, receive or can get the
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46 source code. And you must show them these terms so they know their
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47 rights.
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48
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49 We protect your rights with two steps: (1) copyright the software, and
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50 (2) offer you this license which gives you legal permission to copy,
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51 distribute and/or modify the software.
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52
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53 Also, for each author's protection and ours, we want to make certain
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54 that everyone understands that there is no warranty for this free
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55 software. If the software is modified by someone else and passed on, we
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56 want its recipients to know that what they have is not the original, so
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57 that any problems introduced by others will not reflect on the original
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58 authors' reputations.
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59
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60 Finally, any free program is threatened constantly by software
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61 patents. We wish to avoid the danger that redistributors of a free
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62 program will individually obtain patent licenses, in effect making the
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63 program proprietary. To prevent this, we have made it clear that any
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64 patent must be licensed for everyone's free use or not licensed at all.
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65
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66 The precise terms and conditions for copying, distribution and
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67 modification follow.
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68
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69 @iftex
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70 @unnumberedsec TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
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71 @end iftex
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72 @ifinfo
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73 @center TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
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74 @end ifinfo
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75
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76 @enumerate 0
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77 @item
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78 This License applies to any program or other work which contains
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79 a notice placed by the copyright holder saying it may be distributed
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80 under the terms of this General Public License. The ``Program'', below,
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81 refers to any such program or work, and a ``work based on the Program''
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82 means either the Program or any derivative work under copyright law:
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83 that is to say, a work containing the Program or a portion of it,
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84 either verbatim or with modifications and/or translated into another
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85 language. (Hereinafter, translation is included without limitation in
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86 the term ``modification''.) Each licensee is addressed as ``you''.
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87
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88 Activities other than copying, distribution and modification are not
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89 covered by this License; they are outside its scope. The act of
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90 running the Program is not restricted, and the output from the Program
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91 is covered only if its contents constitute a work based on the
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92 Program (independent of having been made by running the Program).
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93 Whether that is true depends on what the Program does.
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94
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95 @item
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96 You may copy and distribute verbatim copies of the Program's
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97 source code as you receive it, in any medium, provided that you
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98 conspicuously and appropriately publish on each copy an appropriate
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99 copyright notice and disclaimer of warranty; keep intact all the
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100 notices that refer to this License and to the absence of any warranty;
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101 and give any other recipients of the Program a copy of this License
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102 along with the Program.
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103
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104 You may charge a fee for the physical act of transferring a copy, and
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105 you may at your option offer warranty protection in exchange for a fee.
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106
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107 @item
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108 You may modify your copy or copies of the Program or any portion
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109 of it, thus forming a work based on the Program, and copy and
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110 distribute such modifications or work under the terms of Section 1
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111 above, provided that you also meet all of these conditions:
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112
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113 @enumerate a
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114 @item
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115 You must cause the modified files to carry prominent notices
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116 stating that you changed the files and the date of any change.
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117
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118 @item
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119 You must cause any work that you distribute or publish, that in
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120 whole or in part contains or is derived from the Program or any
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121 part thereof, to be licensed as a whole at no charge to all third
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122 parties under the terms of this License.
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123
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124 @item
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125 If the modified program normally reads commands interactively
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126 when run, you must cause it, when started running for such
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127 interactive use in the most ordinary way, to print or display an
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128 announcement including an appropriate copyright notice and a
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129 notice that there is no warranty (or else, saying that you provide
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130 a warranty) and that users may redistribute the program under
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131 these conditions, and telling the user how to view a copy of this
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132 License. (Exception: if the Program itself is interactive but
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133 does not normally print such an announcement, your work based on
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134 the Program is not required to print an announcement.)
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135 @end enumerate
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136
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137 These requirements apply to the modified work as a whole. If
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138 identifiable sections of that work are not derived from the Program,
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139 and can be reasonably considered independent and separate works in
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140 themselves, then this License, and its terms, do not apply to those
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141 sections when you distribute them as separate works. But when you
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142 distribute the same sections as part of a whole which is a work based
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143 on the Program, the distribution of the whole must be on the terms of
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144 this License, whose permissions for other licensees extend to the
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145 entire whole, and thus to each and every part regardless of who wrote it.
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146
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147 Thus, it is not the intent of this section to claim rights or contest
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148 your rights to work written entirely by you; rather, the intent is to
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149 exercise the right to control the distribution of derivative or
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150 collective works based on the Program.
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151
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152 In addition, mere aggregation of another work not based on the Program
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153 with the Program (or with a work based on the Program) on a volume of
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154 a storage or distribution medium does not bring the other work under
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155 the scope of this License.
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156
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157 @item
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158 You may copy and distribute the Program (or a work based on it,
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159 under Section 2) in object code or executable form under the terms of
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160 Sections 1 and 2 above provided that you also do one of the following:
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161
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162 @enumerate a
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163 @item
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164 Accompany it with the complete corresponding machine-readable
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165 source code, which must be distributed under the terms of Sections
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166 1 and 2 above on a medium customarily used for software interchange; or,
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167
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168 @item
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169 Accompany it with a written offer, valid for at least three
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170 years, to give any third party, for a charge no more than your
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171 cost of physically performing source distribution, a complete
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172 machine-readable copy of the corresponding source code, to be
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173 distributed under the terms of Sections 1 and 2 above on a medium
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174 customarily used for software interchange; or,
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175
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176 @item
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177 Accompany it with the information you received as to the offer
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178 to distribute corresponding source code. (This alternative is
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179 allowed only for noncommercial distribution and only if you
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180 received the program in object code or executable form with such
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181 an offer, in accord with Subsection b above.)
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182 @end enumerate
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183
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184 The source code for a work means the preferred form of the work for
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185 making modifications to it. For an executable work, complete source
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186 code means all the source code for all modules it contains, plus any
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187 associated interface definition files, plus the scripts used to
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188 control compilation and installation of the executable. However, as a
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189 special exception, the source code distributed need not include
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190 anything that is normally distributed (in either source or binary
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191 form) with the major components (compiler, kernel, and so on) of the
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192 operating system on which the executable runs, unless that component
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193 itself accompanies the executable.
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194
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195 If distribution of executable or object code is made by offering
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196 access to copy from a designated place, then offering equivalent
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197 access to copy the source code from the same place counts as
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198 distribution of the source code, even though third parties are not
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199 compelled to copy the source along with the object code.
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200
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201 @item
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202 You may not copy, modify, sublicense, or distribute the Program
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203 except as expressly provided under this License. Any attempt
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204 otherwise to copy, modify, sublicense or distribute the Program is
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205 void, and will automatically terminate your rights under this License.
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206 However, parties who have received copies, or rights, from you under
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207 this License will not have their licenses terminated so long as such
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208 parties remain in full compliance.
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209
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210 @item
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211 You are not required to accept this License, since you have not
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212 signed it. However, nothing else grants you permission to modify or
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213 distribute the Program or its derivative works. These actions are
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214 prohibited by law if you do not accept this License. Therefore, by
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215 modifying or distributing the Program (or any work based on the
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216 Program), you indicate your acceptance of this License to do so, and
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217 all its terms and conditions for copying, distributing or modifying
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218 the Program or works based on it.
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219
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220 @item
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221 Each time you redistribute the Program (or any work based on the
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222 Program), the recipient automatically receives a license from the
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223 original licensor to copy, distribute or modify the Program subject to
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224 these terms and conditions. You may not impose any further
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225 restrictions on the recipients' exercise of the rights granted herein.
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226 You are not responsible for enforcing compliance by third parties to
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227 this License.
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228
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229 @item
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230 If, as a consequence of a court judgment or allegation of patent
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231 infringement or for any other reason (not limited to patent issues),
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232 conditions are imposed on you (whether by court order, agreement or
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233 otherwise) that contradict the conditions of this License, they do not
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234 excuse you from the conditions of this License. If you cannot
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235 distribute so as to satisfy simultaneously your obligations under this
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236 License and any other pertinent obligations, then as a consequence you
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237 may not distribute the Program at all. For example, if a patent
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238 license would not permit royalty-free redistribution of the Program by
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239 all those who receive copies directly or indirectly through you, then
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240 the only way you could satisfy both it and this License would be to
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241 refrain entirely from distribution of the Program.
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242
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243 If any portion of this section is held invalid or unenforceable under
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244 any particular circumstance, the balance of the section is intended to
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245 apply and the section as a whole is intended to apply in other
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246 circumstances.
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247
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248 It is not the purpose of this section to induce you to infringe any
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249 patents or other property right claims or to contest validity of any
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250 such claims; this section has the sole purpose of protecting the
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251 integrity of the free software distribution system, which is
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252 implemented by public license practices. Many people have made
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253 generous contributions to the wide range of software distributed
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254 through that system in reliance on consistent application of that
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255 system; it is up to the author/donor to decide if he or she is willing
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256 to distribute software through any other system and a licensee cannot
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257 impose that choice.
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258
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259 This section is intended to make thoroughly clear what is believed to
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260 be a consequence of the rest of this License.
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261
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262 @item
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263 If the distribution and/or use of the Program is restricted in
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264 certain countries either by patents or by copyrighted interfaces, the
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265 original copyright holder who places the Program under this License
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266 may add an explicit geographical distribution limitation excluding
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267 those countries, so that distribution is permitted only in or among
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268 countries not thus excluded. In such case, this License incorporates
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269 the limitation as if written in the body of this License.
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270
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271 @item
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272 The Free Software Foundation may publish revised and/or new versions
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273 of the General Public License from time to time. Such new versions will
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274 be similar in spirit to the present version, but may differ in detail to
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275 address new problems or concerns.
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276
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277 Each version is given a distinguishing version number. If the Program
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278 specifies a version number of this License which applies to it and ``any
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279 later version'', you have the option of following the terms and conditions
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280 either of that version or of any later version published by the Free
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281 Software Foundation. If the Program does not specify a version number of
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282 this License, you may choose any version ever published by the Free Software
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283 Foundation.
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284
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285 @item
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286 If you wish to incorporate parts of the Program into other free
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287 programs whose distribution conditions are different, write to the author
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288 to ask for permission. For software which is copyrighted by the Free
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289 Software Foundation, write to the Free Software Foundation; we sometimes
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290 make exceptions for this. Our decision will be guided by the two goals
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291 of preserving the free status of all derivatives of our free software and
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292 of promoting the sharing and reuse of software generally.
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293
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294 @iftex
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295 @heading NO WARRANTY
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296 @end iftex
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297 @ifinfo
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298 @center NO WARRANTY
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299 @end ifinfo
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300
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301 @item
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302 BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
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303 FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW@. EXCEPT WHEN
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304 OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
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305 PROVIDE THE PROGRAM ``AS IS'' WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
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306 OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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307 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE@. THE ENTIRE RISK AS
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308 TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU@. SHOULD THE
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309 PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
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310 REPAIR OR CORRECTION.
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311
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312 @item
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313 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
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314 WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
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315 REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
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316 INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
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317 OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
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318 TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
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319 YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
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320 PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
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321 POSSIBILITY OF SUCH DAMAGES.
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322 @end enumerate
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323
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324 @iftex
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325 @heading END OF TERMS AND CONDITIONS
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326 @end iftex
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327 @ifinfo
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328 @center END OF TERMS AND CONDITIONS
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329 @end ifinfo
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330
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331 @page
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332 @unnumberedsec How to Apply These Terms to Your New Programs
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333
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334 If you develop a new program, and you want it to be of the greatest
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335 possible use to the public, the best way to achieve this is to make it
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336 free software which everyone can redistribute and change under these terms.
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337
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338 To do so, attach the following notices to the program. It is safest
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339 to attach them to the start of each source file to most effectively
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340 convey the exclusion of warranty; and each file should have at least
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341 the ``copyright'' line and a pointer to where the full notice is found.
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342
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343 @smallexample
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344 @var{one line to give the program's name and an idea of what it does.}
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345 Copyright (C) 19@var{yy} @var{name of author}
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346
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347 This program is free software; you can redistribute it and/or
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348 modify it under the terms of the GNU General Public License
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349 as published by the Free Software Foundation; either version 2
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350 of the License, or (at your option) any later version.
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351
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352 This program is distributed in the hope that it will be useful,
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353 but WITHOUT ANY WARRANTY; without even the implied warranty of
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354 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE@. See the
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355 GNU General Public License for more details.
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356
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357 You should have received a copy of the GNU General Public License
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358 along with this program; if not, write to the Free Software
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359 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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360 @end smallexample
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361
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362 Also add information on how to contact you by electronic and paper mail.
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363
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364 If the program is interactive, make it output a short notice like this
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365 when it starts in an interactive mode:
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366
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367 @smallexample
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368 Gnomovision version 69, Copyright (C) 19@var{yy} @var{name of author}
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369 Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
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370 type `show w'. This is free software, and you are welcome
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371 to redistribute it under certain conditions; type `show c'
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372 for details.
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373 @end smallexample
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374
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375 The hypothetical commands @samp{show w} and @samp{show c} should show
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376 the appropriate parts of the General Public License. Of course, the
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377 commands you use may be called something other than @samp{show w} and
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378 @samp{show c}; they could even be mouse-clicks or menu items---whatever
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379 suits your program.
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380
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|
|
381 You should also get your employer (if you work as a programmer) or your
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|
|
382 school, if any, to sign a ``copyright disclaimer'' for the program, if
|
|
|
383 necessary. Here is a sample; alter the names:
|
|
|
384
|
|
|
385 @smallexample
|
|
|
386 @group
|
|
|
387 Yoyodyne, Inc., hereby disclaims all copyright
|
|
|
388 interest in the program `Gnomovision'
|
|
|
389 (which makes passes at compilers) written
|
|
|
390 by James Hacker.
|
|
|
391
|
|
|
392 @var{signature of Ty Coon}, 1 April 1989
|
|
|
393 Ty Coon, President of Vice
|
|
|
394 @end group
|
|
|
395 @end smallexample
|
|
|
396
|
|
|
397 This General Public License does not permit incorporating your program into
|
|
|
398 proprietary programs. If your program is a subroutine library, you may
|
|
|
399 consider it more useful to permit linking proprietary applications with the
|
|
|
400 library. If this is what you want to do, use the GNU Library General
|
|
|
401 Public License instead of this License.
|
|
|
402
|
|
|
403 @node Introduction, Lisp Data Types, Copying, Top
|
|
|
404 @chapter Introduction
|
|
|
405
|
|
|
406 Most of the XEmacs text editor is written in the programming
|
|
|
407 language called XEmacs Lisp. You can write new code in XEmacs Lisp and
|
|
|
408 install it as an extension to the editor. However, XEmacs Lisp is more
|
|
|
409 than a mere ``extension language''; it is a full computer programming
|
|
|
410 language in its own right. You can use it as you would any other
|
|
|
411 programming language.
|
|
|
412
|
|
|
413 Because XEmacs Lisp is designed for use in an editor, it has special
|
|
|
414 features for scanning and parsing text as well as features for handling
|
|
|
415 files, buffers, displays, subprocesses, and so on. XEmacs Lisp is
|
|
|
416 closely integrated with the editing facilities; thus, editing commands
|
|
|
417 are functions that can also conveniently be called from Lisp programs,
|
|
|
418 and parameters for customization are ordinary Lisp variables.
|
|
|
419
|
|
|
420 This manual describes XEmacs Lisp, presuming considerable familiarity
|
|
|
421 with the use of XEmacs for editing. (See @cite{The XEmacs Reference
|
|
|
422 Manual}, for this basic information.) Generally speaking, the earlier
|
|
|
423 chapters describe features of XEmacs Lisp that have counterparts in many
|
|
|
424 programming languages, and later chapters describe features that are
|
|
|
425 peculiar to XEmacs Lisp or relate specifically to editing.
|
|
|
426
|
|
227
|
427 This is edition 3.3.
|
|
0
|
428
|
|
|
429 @menu
|
|
|
430 * Caveats:: Flaws and a request for help.
|
|
|
431 * Lisp History:: XEmacs Lisp is descended from Maclisp.
|
|
|
432 * Conventions:: How the manual is formatted.
|
|
|
433 * Acknowledgements:: The authors, editors, and sponsors of this manual.
|
|
|
434 @end menu
|
|
|
435
|
|
|
436 @node Caveats
|
|
|
437 @section Caveats
|
|
|
438
|
|
|
439 This manual has gone through numerous drafts. It is nearly complete
|
|
|
440 but not flawless. There are a few topics that are not covered, either
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|
|
441 because we consider them secondary (such as most of the individual
|
|
|
442 modes) or because they are yet to be written. Because we are not able
|
|
|
443 to deal with them completely, we have left out several parts
|
|
|
444 intentionally. This includes most information about usage on VMS.
|
|
|
445
|
|
|
446 The manual should be fully correct in what it does cover, and it is
|
|
|
447 therefore open to criticism on anything it says---from specific examples
|
|
|
448 and descriptive text, to the ordering of chapters and sections. If
|
|
|
449 something is confusing, or you find that you have to look at the sources
|
|
|
450 or experiment to learn something not covered in the manual, then perhaps
|
|
|
451 the manual should be fixed. Please let us know.
|
|
|
452
|
|
|
453 @iftex
|
|
|
454 As you use the manual, we ask that you mark pages with corrections so
|
|
|
455 you can later look them up and send them in. If you think of a simple,
|
|
|
456 real-life example for a function or group of functions, please make an
|
|
|
457 effort to write it up and send it in. Please reference any comments to
|
|
|
458 the chapter name, section name, and function name, as appropriate, since
|
|
|
459 page numbers and chapter and section numbers will change and we may have
|
|
|
460 trouble finding the text you are talking about. Also state the number
|
|
|
461 of the edition you are criticizing.
|
|
|
462 @end iftex
|
|
|
463 @ifinfo
|
|
|
464
|
|
|
465 As you use this manual, we ask that you send corrections as soon as you
|
|
|
466 find them. If you think of a simple, real life example for a function
|
|
|
467 or group of functions, please make an effort to write it up and send it
|
|
|
468 in. Please reference any comments to the node name and function or
|
|
|
469 variable name, as appropriate. Also state the number of the edition
|
|
|
470 which you are criticizing.
|
|
|
471 @end ifinfo
|
|
|
472
|
|
|
473 This manual was originally written for FSF Emacs 19 and was updated by
|
|
|
474 Ben Wing (wing@@666.com) for Lucid Emacs 19.10 and later for XEmacs
|
|
120
|
475 19.12, 19.13, 19.14, and 20.0. It was further updated by the XEmacs
|
|
371
|
476 Development Team for 19.15 and 20.1. Please send comments and
|
|
|
477 corrections relating to XEmacs-specific portions of this manual to
|
|
0
|
478 @example
|
|
|
479 xemacs@@xemacs.org
|
|
|
480 @end example
|
|
|
481
|
|
|
482 or post to the newsgroup
|
|
|
483 @example
|
|
|
484 comp.emacs.xemacs
|
|
|
485 @end example
|
|
|
486
|
|
|
487 @noindent
|
|
|
488 @display
|
|
|
489 --Ben Wing
|
|
|
490 @end display
|
|
|
491
|
|
|
492 @node Lisp History
|
|
|
493 @section Lisp History
|
|
|
494 @cindex Lisp history
|
|
|
495
|
|
|
496 Lisp (LISt Processing language) was first developed in the late 1950's
|
|
|
497 at the Massachusetts Institute of Technology for research in artificial
|
|
|
498 intelligence. The great power of the Lisp language makes it superior
|
|
|
499 for other purposes as well, such as writing editing commands.
|
|
|
500
|
|
|
501 @cindex Maclisp
|
|
|
502 @cindex Common Lisp
|
|
|
503 Dozens of Lisp implementations have been built over the years, each
|
|
|
504 with its own idiosyncrasies. Many of them were inspired by Maclisp,
|
|
|
505 which was written in the 1960's at MIT's Project MAC. Eventually the
|
|
|
506 implementors of the descendants of Maclisp came together and developed a
|
|
|
507 standard for Lisp systems, called Common Lisp.
|
|
|
508
|
|
|
509 XEmacs Lisp is largely inspired by Maclisp, and a little by Common
|
|
|
510 Lisp. If you know Common Lisp, you will notice many similarities.
|
|
|
511 However, many of the features of Common Lisp have been omitted or
|
|
|
512 simplified in order to reduce the memory requirements of XEmacs.
|
|
|
513 Sometimes the simplifications are so drastic that a Common Lisp user
|
|
|
514 might be very confused. We will occasionally point out how XEmacs
|
|
|
515 Lisp differs from Common Lisp. If you don't know Common Lisp, don't
|
|
|
516 worry about it; this manual is self-contained.
|
|
|
517
|
|
|
518 @node Conventions
|
|
|
519 @section Conventions
|
|
|
520
|
|
|
521 This section explains the notational conventions that are used in this
|
|
|
522 manual. You may want to skip this section and refer back to it later.
|
|
|
523
|
|
|
524 @menu
|
|
|
525 * Some Terms:: Explanation of terms we use in this manual.
|
|
|
526 * nil and t:: How the symbols @code{nil} and @code{t} are used.
|
|
|
527 * Evaluation Notation:: The format we use for examples of evaluation.
|
|
|
528 * Printing Notation:: The format we use for examples that print output.
|
|
|
529 * Error Messages:: The format we use for examples of errors.
|
|
|
530 * Buffer Text Notation:: The format we use for buffer contents in examples.
|
|
|
531 * Format of Descriptions:: Notation for describing functions, variables, etc.
|
|
|
532 @end menu
|
|
|
533
|
|
|
534 @node Some Terms
|
|
|
535 @subsection Some Terms
|
|
|
536
|
|
|
537 Throughout this manual, the phrases ``the Lisp reader'' and ``the Lisp
|
|
|
538 printer'' are used to refer to those routines in Lisp that convert
|
|
|
539 textual representations of Lisp objects into actual Lisp objects, and vice
|
|
|
540 versa. @xref{Printed Representation}, for more details. You, the
|
|
|
541 person reading this manual, are thought of as ``the programmer'' and are
|
|
|
542 addressed as ``you''. ``The user'' is the person who uses Lisp programs,
|
|
|
543 including those you write.
|
|
|
544
|
|
|
545 @cindex fonts
|
|
|
546 Examples of Lisp code appear in this font or form: @code{(list 1 2
|
|
|
547 3)}. Names that represent arguments or metasyntactic variables appear
|
|
|
548 in this font or form: @var{first-number}.
|
|
|
549
|
|
|
550 @node nil and t
|
|
|
551 @subsection @code{nil} and @code{t}
|
|
|
552 @cindex @code{nil}, uses of
|
|
|
553 @cindex truth value
|
|
|
554 @cindex boolean
|
|
|
555 @cindex false
|
|
|
556
|
|
|
557 In Lisp, the symbol @code{nil} has three separate meanings: it
|
|
|
558 is a symbol with the name @samp{nil}; it is the logical truth value
|
|
|
559 @var{false}; and it is the empty list---the list of zero elements.
|
|
|
560 When used as a variable, @code{nil} always has the value @code{nil}.
|
|
|
561
|
|
|
562 As far as the Lisp reader is concerned, @samp{()} and @samp{nil} are
|
|
|
563 identical: they stand for the same object, the symbol @code{nil}. The
|
|
|
564 different ways of writing the symbol are intended entirely for human
|
|
|
565 readers. After the Lisp reader has read either @samp{()} or @samp{nil},
|
|
|
566 there is no way to determine which representation was actually written
|
|
|
567 by the programmer.
|
|
|
568
|
|
|
569 In this manual, we use @code{()} when we wish to emphasize that it
|
|
|
570 means the empty list, and we use @code{nil} when we wish to emphasize
|
|
|
571 that it means the truth value @var{false}. That is a good convention to use
|
|
|
572 in Lisp programs also.
|
|
|
573
|
|
|
574 @example
|
|
|
575 (cons 'foo ()) ; @r{Emphasize the empty list}
|
|
|
576 (not nil) ; @r{Emphasize the truth value @var{false}}
|
|
|
577 @end example
|
|
|
578
|
|
|
579 @cindex @code{t} and truth
|
|
|
580 @cindex true
|
|
|
581 In contexts where a truth value is expected, any non-@code{nil} value
|
|
|
582 is considered to be @var{true}. However, @code{t} is the preferred way
|
|
|
583 to represent the truth value @var{true}. When you need to choose a
|
|
|
584 value which represents @var{true}, and there is no other basis for
|
|
|
585 choosing, use @code{t}. The symbol @code{t} always has value @code{t}.
|
|
|
586
|
|
|
587 In XEmacs Lisp, @code{nil} and @code{t} are special symbols that always
|
|
|
588 evaluate to themselves. This is so that you do not need to quote them
|
|
|
589 to use them as constants in a program. An attempt to change their
|
|
|
590 values results in a @code{setting-constant} error. @xref{Accessing
|
|
|
591 Variables}.
|
|
|
592
|
|
|
593 @node Evaluation Notation
|
|
|
594 @subsection Evaluation Notation
|
|
|
595 @cindex evaluation notation
|
|
|
596 @cindex documentation notation
|
|
|
597
|
|
|
598 A Lisp expression that you can evaluate is called a @dfn{form}.
|
|
|
599 Evaluating a form always produces a result, which is a Lisp object. In
|
|
|
600 the examples in this manual, this is indicated with @samp{@result{}}:
|
|
|
601
|
|
|
602 @example
|
|
|
603 (car '(1 2))
|
|
|
604 @result{} 1
|
|
|
605 @end example
|
|
|
606
|
|
|
607 @noindent
|
|
|
608 You can read this as ``@code{(car '(1 2))} evaluates to 1''.
|
|
|
609
|
|
|
610 When a form is a macro call, it expands into a new form for Lisp to
|
|
|
611 evaluate. We show the result of the expansion with
|
|
|
612 @samp{@expansion{}}. We may or may not show the actual result of the
|
|
|
613 evaluation of the expanded form.
|
|
|
614
|
|
|
615 @example
|
|
116
|
616 (news-cadr '(a b c))
|
|
|
617 @expansion{} (car (cdr '(a b c)))
|
|
|
618 @result{} b
|
|
0
|
619 @end example
|
|
|
620
|
|
|
621 Sometimes to help describe one form we show another form that
|
|
|
622 produces identical results. The exact equivalence of two forms is
|
|
|
623 indicated with @samp{@equiv{}}.
|
|
|
624
|
|
|
625 @example
|
|
116
|
626 (cons 'a nil) @equiv{} (list 'a)
|
|
0
|
627 @end example
|
|
|
628
|
|
|
629 @node Printing Notation
|
|
|
630 @subsection Printing Notation
|
|
|
631 @cindex printing notation
|
|
|
632
|
|
|
633 Many of the examples in this manual print text when they are
|
|
|
634 evaluated. If you execute example code in a Lisp Interaction buffer
|
|
|
635 (such as the buffer @samp{*scratch*}), the printed text is inserted into
|
|
|
636 the buffer. If you execute the example by other means (such as by
|
|
|
637 evaluating the function @code{eval-region}), the printed text is
|
|
|
638 displayed in the echo area. You should be aware that text displayed in
|
|
|
639 the echo area is truncated to a single line.
|
|
|
640
|
|
|
641 Examples in this manual indicate printed text with @samp{@print{}},
|
|
|
642 irrespective of where that text goes. The value returned by evaluating
|
|
|
643 the form (here @code{bar}) follows on a separate line.
|
|
|
644
|
|
|
645 @example
|
|
|
646 @group
|
|
|
647 (progn (print 'foo) (print 'bar))
|
|
|
648 @print{} foo
|
|
|
649 @print{} bar
|
|
|
650 @result{} bar
|
|
|
651 @end group
|
|
|
652 @end example
|
|
|
653
|
|
|
654 @node Error Messages
|
|
|
655 @subsection Error Messages
|
|
|
656 @cindex error message notation
|
|
|
657
|
|
|
658 Some examples signal errors. This normally displays an error message
|
|
|
659 in the echo area. We show the error message on a line starting with
|
|
|
660 @samp{@error{}}. Note that @samp{@error{}} itself does not appear in
|
|
|
661 the echo area.
|
|
|
662
|
|
|
663 @example
|
|
|
664 (+ 23 'x)
|
|
|
665 @error{} Wrong type argument: integer-or-marker-p, x
|
|
|
666 @end example
|
|
|
667
|
|
|
668 @node Buffer Text Notation
|
|
|
669 @subsection Buffer Text Notation
|
|
|
670 @cindex buffer text notation
|
|
|
671
|
|
|
672 Some examples show modifications to text in a buffer, with ``before''
|
|
|
673 and ``after'' versions of the text. These examples show the contents of
|
|
|
674 the buffer in question between two lines of dashes containing the buffer
|
|
|
675 name. In addition, @samp{@point{}} indicates the location of point.
|
|
|
676 (The symbol for point, of course, is not part of the text in the buffer;
|
|
|
677 it indicates the place @emph{between} two characters where point is
|
|
|
678 located.)
|
|
|
679
|
|
|
680 @example
|
|
|
681 ---------- Buffer: foo ----------
|
|
|
682 This is the @point{}contents of foo.
|
|
|
683 ---------- Buffer: foo ----------
|
|
|
684
|
|
|
685 (insert "changed ")
|
|
|
686 @result{} nil
|
|
|
687 ---------- Buffer: foo ----------
|
|
|
688 This is the changed @point{}contents of foo.
|
|
|
689 ---------- Buffer: foo ----------
|
|
|
690 @end example
|
|
|
691
|
|
|
692 @node Format of Descriptions
|
|
|
693 @subsection Format of Descriptions
|
|
|
694 @cindex description format
|
|
|
695
|
|
|
696 Functions, variables, macros, commands, user options, and special
|
|
|
697 forms are described in this manual in a uniform format. The first
|
|
|
698 line of a description contains the name of the item followed by its
|
|
|
699 arguments, if any.
|
|
|
700 @ifinfo
|
|
|
701 The category---function, variable, or whatever---appears at the
|
|
|
702 beginning of the line.
|
|
|
703 @end ifinfo
|
|
|
704 @iftex
|
|
|
705 The category---function, variable, or whatever---is printed next to the
|
|
|
706 right margin.
|
|
|
707 @end iftex
|
|
|
708 The description follows on succeeding lines, sometimes with examples.
|
|
|
709
|
|
|
710 @menu
|
|
|
711 * A Sample Function Description:: A description of an imaginary
|
|
|
712 function, @code{foo}.
|
|
|
713 * A Sample Variable Description:: A description of an imaginary
|
|
|
714 variable,
|
|
|
715 @code{electric-future-map}.
|
|
|
716 @end menu
|
|
|
717
|
|
|
718 @node A Sample Function Description
|
|
|
719 @subsubsection A Sample Function Description
|
|
|
720 @cindex function descriptions
|
|
|
721 @cindex command descriptions
|
|
|
722 @cindex macro descriptions
|
|
|
723 @cindex special form descriptions
|
|
|
724
|
|
|
725 In a function description, the name of the function being described
|
|
|
726 appears first. It is followed on the same line by a list of parameters.
|
|
|
727 The names used for the parameters are also used in the body of the
|
|
|
728 description.
|
|
|
729
|
|
|
730 The appearance of the keyword @code{&optional} in the parameter list
|
|
|
731 indicates that the arguments for subsequent parameters may be omitted
|
|
|
732 (omitted parameters default to @code{nil}). Do not write
|
|
|
733 @code{&optional} when you call the function.
|
|
|
734
|
|
|
735 The keyword @code{&rest} (which will always be followed by a single
|
|
|
736 parameter) indicates that any number of arguments can follow. The value
|
|
|
737 of the single following parameter will be a list of all these arguments.
|
|
|
738 Do not write @code{&rest} when you call the function.
|
|
|
739
|
|
|
740 Here is a description of an imaginary function @code{foo}:
|
|
|
741
|
|
|
742 @defun foo integer1 &optional integer2 &rest integers
|
|
|
743 The function @code{foo} subtracts @var{integer1} from @var{integer2},
|
|
|
744 then adds all the rest of the arguments to the result. If @var{integer2}
|
|
|
745 is not supplied, then the number 19 is used by default.
|
|
|
746
|
|
|
747 @example
|
|
|
748 (foo 1 5 3 9)
|
|
|
749 @result{} 16
|
|
|
750 (foo 5)
|
|
|
751 @result{} 14
|
|
|
752 @end example
|
|
|
753
|
|
|
754 More generally,
|
|
|
755
|
|
|
756 @example
|
|
|
757 (foo @var{w} @var{x} @var{y}@dots{})
|
|
|
758 @equiv{}
|
|
|
759 (+ (- @var{x} @var{w}) @var{y}@dots{})
|
|
|
760 @end example
|
|
|
761 @end defun
|
|
|
762
|
|
|
763 Any parameter whose name contains the name of a type (e.g.,
|
|
|
764 @var{integer}, @var{integer1} or @var{buffer}) is expected to be of that
|
|
|
765 type. A plural of a type (such as @var{buffers}) often means a list of
|
|
|
766 objects of that type. Parameters named @var{object} may be of any type.
|
|
|
767 (@xref{Lisp Data Types}, for a list of XEmacs object types.)
|
|
|
768 Parameters with other sorts of names (e.g., @var{new-file}) are
|
|
|
769 discussed specifically in the description of the function. In some
|
|
|
770 sections, features common to parameters of several functions are
|
|
|
771 described at the beginning.
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|
|
772
|
|
|
773 @xref{Lambda Expressions}, for a more complete description of optional
|
|
|
774 and rest arguments.
|
|
|
775
|
|
|
776 Command, macro, and special form descriptions have the same format,
|
|
|
777 but the word `Function' is replaced by `Command', `Macro', or `Special
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|
|
778 Form', respectively. Commands are simply functions that may be called
|
|
|
779 interactively; macros process their arguments differently from functions
|
|
|
780 (the arguments are not evaluated), but are presented the same way.
|
|
|
781
|
|
|
782 Special form descriptions use a more complex notation to specify
|
|
|
783 optional and repeated parameters because they can break the argument
|
|
|
784 list down into separate arguments in more complicated ways.
|
|
|
785 @samp{@code{@r{[}@var{optional-arg}@r{]}}} means that @var{optional-arg} is
|
|
|
786 optional and @samp{@var{repeated-args}@dots{}} stands for zero or more
|
|
|
787 arguments. Parentheses are used when several arguments are grouped into
|
|
|
788 additional levels of list structure. Here is an example:
|
|
|
789
|
|
|
790 @defspec count-loop (@var{var} [@var{from} @var{to} [@var{inc}]]) @var{body}@dots{}
|
|
|
791 This imaginary special form implements a loop that executes the
|
|
|
792 @var{body} forms and then increments the variable @var{var} on each
|
|
|
793 iteration. On the first iteration, the variable has the value
|
|
|
794 @var{from}; on subsequent iterations, it is incremented by 1 (or by
|
|
|
795 @var{inc} if that is given). The loop exits before executing @var{body}
|
|
|
796 if @var{var} equals @var{to}. Here is an example:
|
|
|
797
|
|
|
798 @example
|
|
|
799 (count-loop (i 0 10)
|
|
|
800 (prin1 i) (princ " ")
|
|
|
801 (prin1 (aref vector i)) (terpri))
|
|
|
802 @end example
|
|
|
803
|
|
|
804 If @var{from} and @var{to} are omitted, then @var{var} is bound to
|
|
|
805 @code{nil} before the loop begins, and the loop exits if @var{var} is
|
|
|
806 non-@code{nil} at the beginning of an iteration. Here is an example:
|
|
|
807
|
|
|
808 @example
|
|
|
809 (count-loop (done)
|
|
|
810 (if (pending)
|
|
|
811 (fixit)
|
|
|
812 (setq done t)))
|
|
|
813 @end example
|
|
|
814
|
|
|
815 In this special form, the arguments @var{from} and @var{to} are
|
|
|
816 optional, but must both be present or both absent. If they are present,
|
|
|
817 @var{inc} may optionally be specified as well. These arguments are
|
|
|
818 grouped with the argument @var{var} into a list, to distinguish them
|
|
|
819 from @var{body}, which includes all remaining elements of the form.
|
|
|
820 @end defspec
|
|
|
821
|
|
|
822 @node A Sample Variable Description
|
|
|
823 @subsubsection A Sample Variable Description
|
|
|
824 @cindex variable descriptions
|
|
|
825 @cindex option descriptions
|
|
|
826
|
|
|
827 A @dfn{variable} is a name that can hold a value. Although any
|
|
|
828 variable can be set by the user, certain variables that exist
|
|
|
829 specifically so that users can change them are called @dfn{user
|
|
|
830 options}. Ordinary variables and user options are described using a
|
|
|
831 format like that for functions except that there are no arguments.
|
|
|
832
|
|
|
833 Here is a description of the imaginary @code{electric-future-map}
|
|
|
834 variable.@refill
|
|
|
835
|
|
|
836 @defvar electric-future-map
|
|
|
837 The value of this variable is a full keymap used by Electric Command
|
|
|
838 Future mode. The functions in this map allow you to edit commands you
|
|
|
839 have not yet thought about executing.
|
|
|
840 @end defvar
|
|
|
841
|
|
|
842 User option descriptions have the same format, but `Variable' is
|
|
|
843 replaced by `User Option'.
|
|
|
844
|
|
|
845 @node Acknowledgements
|
|
|
846 @section Acknowledgements
|
|
|
847
|
|
|
848 This manual was based on the GNU Emacs Lisp Reference Manual, version
|
|
|
849 2.4, written by Robert Krawitz, Bil Lewis, Dan LaLiberte, Richard
|
|
|
850 M. Stallman and Chris Welty, the volunteers of the GNU manual group, in
|
|
|
851 an effort extending over several years. Robert J. Chassell helped to
|
|
|
852 review and edit the manual, with the support of the Defense Advanced
|
|
|
853 Research Projects Agency, ARPA Order 6082, arranged by Warren A. Hunt,
|
|
|
854 Jr. of Computational Logic, Inc.
|
|
|
855
|
|
54
|
856 Ben Wing adapted this manual for XEmacs 19.14 and 20.0, and earlier
|
|
0
|
857 for Lucid Emacs 19.10, XEmacs 19.12, and XEmacs 19.13. He is the sole
|
|
|
858 author of many of the manual sections, in particular the XEmacs-specific
|
|
|
859 sections: events, faces, extents, glyphs, specifiers, toolbar, menubars,
|
|
|
860 scrollbars, dialog boxes, devices, consoles, hash tables, range tables,
|
|
|
861 char tables, databases, and others. The section on annotations was
|
|
227
|
862 originally written by Chuck Thompson. Corrections to v3.1 and later were
|
|
|
863 done by Martin Buchholz, Steve Baur, and Hrvoje Niksic.
|
|
0
|
864
|
|
|
865 Corrections to the original GNU Emacs Lisp Reference Manual were
|
|
|
866 supplied by Karl Berry, Jim Blandy, Bard Bloom, Stephane Boucher, David
|
|
|
867 Boyes, Alan Carroll, Richard Davis, Lawrence R. Dodd, Peter Doornbosch,
|
|
|
868 David A. Duff, Chris Eich, Beverly Erlebacher, David Eckelkamp, Ralf
|
|
|
869 Fassel, Eirik Fuller, Stephen Gildea, Bob Glickstein, Eric Hanchrow,
|
|
|
870 George Hartzell, Nathan Hess, Masayuki Ida, Dan Jacobson, Jak Kirman,
|
|
|
871 Bob Knighten, Frederick M. Korz, Joe Lammens, Glenn M. Lewis, K. Richard
|
|
|
872 Magill, Brian Marick, Roland McGrath, Skip Montanaro, John Gardiner
|
|
|
873 Myers, Thomas A. Peterson, Francesco Potorti, Friedrich Pukelsheim,
|
|
|
874 Arnold D. Robbins, Raul Rockwell, Per Starback, Shinichirou Sugou, Kimmo
|
|
|
875 Suominen, Edward Tharp, Bill Trost, Rickard Westman, Jean White, Matthew
|
|
|
876 Wilding, Carl Witty, Dale Worley, Rusty Wright, and David D. Zuhn.
|
