Update of /project/lispfaq/cvsroot/lispfaq In directory common-lisp.net:/tmp/cvs-serv16736

Modified Files: __FILE__.xml apply-macros.xml array-initialize.xml books.xml continuations.xml faq.xsl flet.xml freelisp.xml on-topic.xml online.xml Log Message: - minor formatting changes

Date: Mon Mar 22 15:07:42 2004 Author: emarsden

Index: lispfaq/__FILE__.xml diff -u lispfaq/__FILE__.xml:1.1 lispfaq/__FILE__.xml:1.2 --- lispfaq/__FILE__.xml:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/__FILE__.xml Mon Mar 22 15:07:41 2004 @@ -1,31 +1,32 @@ <qandaentry> <question> <para> - What is the Lisp equivalent of the __FILE__ and __LINE__ ANSI C - preprocessor macros? How do I find out where an error occurred? + What is the Lisp equivalent of the <symbol>__FILE__</symbol> and + <symbol>__LINE__</symbol> <acronym>ANSI</acronym> C preprocessor + macros? How do I find out where an error occurred? </para> </question> <answer> <para> - There is no direct equivalent of __FILE__ and __LINE__ in ANSI - Common Lisp; this is perhaps most simply explained by the fact - that CL is not particularly a file-oriented and definitely not - a line-oriented language. That said, your particular - implementation may carry around some information about where - functions were compiled, and COMPILE-FILE binds the special - variables *COMPILE-FILE-TRUENAME* and *COMPILE-FILE-PATHNAME*. + There is no direct equivalent of <symbol>__FILE__</symbol> and + <symbol>__LINE__</symbol> in ANSI Common Lisp; this is perhaps + most simply explained by the fact that CL is not particularly a + file-oriented and definitely not a line-oriented language. That + said, your particular implementation may carry around some + information about where functions were compiled, and + <code>COMPILE-FILE</code> binds the special variables + <code>*COMPILE-FILE-TRUENAME*</code> and + <code>*COMPILE-FILE-PATHNAME*</code>. </para> </answer> <answer> - <para> + <programlisting> (defun foo () (break "Stopped inside ~S" (the-function-i-am-in))) - </para> - <para> + (setf (symbol-function 'bar) (symbol-function 'foo)) - </para> - <para> + (bar) - </para> + </programlisting> <para> Are you in a breakpoint in FOO or in BAR? </para>

Index: lispfaq/apply-macros.xml diff -u lispfaq/apply-macros.xml:1.1 lispfaq/apply-macros.xml:1.2 --- lispfaq/apply-macros.xml:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/apply-macros.xml Mon Mar 22 15:07:41 2004 @@ -13,48 +13,43 @@ </para>

<para> - OK, so what's the <emphasis>real</emphasis> reason? The - reason that <function>AND</function> and - <function>OR</function> are macros rather than functions - is because they implement control structure in addition to - computing a boolean value. They evaluate their subforms - sequentially from left/top to right/bottom, and stop - evaluating subforms as soon as the result can be - determined (in the case of <function>AND</function>, as + OK, so what's the <emphasis>real</emphasis> reason? The reason + that <function>AND</function> and <function>OR</function> are + macros rather than functions is because they implement control + structure in addition to computing a boolean value. They + evaluate their subforms sequentially from left/top to + right/bottom, and stop evaluating subforms as soon as the result + can be determined (in the case of <function>AND</function>, as soon as a subform returns NIL; in the case of - <function>OR</function>, as soon as one returns non-NIL); - this is referred to as "short circuiting" in computer - language parlance. <function>APPLY</function> and - <function>FUNCALL</function>, however, are ordinary - functions; therefore, their arguments are evaluated - automatically, before they are called. Thus, were - <function>APPLY</function> able to be used with - <function>#'AND</function>, the short-circuiting would be - defeated. + <function>OR</function>, as soon as one returns non-NIL); this + is referred to as "short circuiting" in computer language + parlance. <function>APPLY</function> and + <function>FUNCALL</function>, however, are ordinary functions; + therefore, their arguments are evaluated automatically, before + they are called. Thus, were <function>APPLY</function> able to + be used with <function>#'AND</function>, the short-circuiting + would be defeated. </para>

<para> - Perhaps you don't really care about the - short-circuiting, and simply want the functional, boolean - interpretation. While this may be a reasonable - interpretation of trying to apply AND or OR, it doesn't - generalize to other macros well, so there's no obvious way - to have the Lisp system "do the right thing" when trying - to apply macros. The only function associated with a + Perhaps you don't really care about the short-circuiting, and + simply want the functional, boolean interpretation. While this + may be a reasonable interpretation of trying to apply AND or OR, + it doesn't generalize to other macros well, so there's no + obvious way to have the Lisp system "do the right thing" when + trying to apply macros. The only function associated with a macro is its expander function; this function accepts and - returns and form, so it cannot be used to compute the - value. + returns and form, so it cannot be used to compute the value. </para>

<para> The Common Lisp functions <function>EVERY</function> and - <function>SOME</function> can be used to get the - functionality you intend when trying to apply - <function>#'AND</function> and <function>#'OR</function>. - For instance, the erroneous form: - <userinput>(apply #'and *list*)</userinput> - can be translated to the correct form: - <userinput>(every #'identity *list*)</userinput>. + <function>SOME</function> can be used to get the functionality + you intend when trying to apply <function>#'AND</function> and + <function>#'OR</function>. For instance, the erroneous form: + <userinput>(apply #'and *list*)</userinput> can be translated to + the correct form: <userinput>(every #'identity + *list*)</userinput>. </para> </answer> </qandaentry>

Index: lispfaq/array-initialize.xml diff -u lispfaq/array-initialize.xml:1.1 lispfaq/array-initialize.xml:1.2 --- lispfaq/array-initialize.xml:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/array-initialize.xml Mon Mar 22 15:07:41 2004 @@ -1,15 +1,24 @@ <qandaentry> <question> <para> - I want an array of foos, but (make-array 10 :initial-element - (make-foo)) causes strange bugs. Why? + I want an array of foos, but + + <programlisting> + (make-array 10 :initial-element (make-foo)) + </programlisting> + + causes strange bugs. Why? </para> </question> <answer> <para> Well, the array created above contains 10 pointers to the same foo, which will indeed cause strange bugs. The correct way to - initialize your array is probably (map-into (make-array 10) #'make-foo) + initialize your array is probably + + <programlisting> + (map-into (make-array 10) #'make-foo) + </programlisting> </para> </answer> </qandaentry>

Index: lispfaq/books.xml diff -u lispfaq/books.xml:1.1 lispfaq/books.xml:1.2 --- lispfaq/books.xml:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/books.xml Mon Mar 22 15:07:41 2004 @@ -1,6 +1,5 @@ <qandaentry> <question> - <para>What books should I read to learn more about - lisp?</para> + <para>What books should I read to learn more about lisp?</para> </question> </qandaentry>

Index: lispfaq/continuations.xml diff -u lispfaq/continuations.xml:1.1 lispfaq/continuations.xml:1.2 --- lispfaq/continuations.xml:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/continuations.xml Mon Mar 22 15:07:41 2004 @@ -1,26 +1,26 @@ <qandaentry> - <question> - <para>Why doesn't Common Lisp have continuations?</para> - </question> - <answer> - <para> - Continuations are a great theoretical tool; if a language has - first-class, multiply invocable continuations then one can build - threads, exceptions, coroutines, and the kitchen sink on top. - </para> - <para> - However, there is an implementation burden with continuations; - supporting first-class, multiply invocable continuations - complicates things tremendously for the Lisp implementor. The - ANSI standardizing committee J13, mindful of this, took the view - that it would be better to specify the user-level control - structure (CATCH, UNWIND-PROTECT, and so on) and let - implementors choose whether to build those on top of - continuations or not. - </para> - <para> - If you need to play with continuations, you should use a Scheme - implementation. - </para> - </answer> + <question> + <para>Why doesn't Common Lisp have continuations?</para> + </question> + <answer> + <para> + Continuations are a great theoretical tool; if a language has + first-class, multiply invocable continuations then one can build + threads, exceptions, coroutines, and the kitchen sink on top. + </para> + <para> + However, there is an implementation burden with continuations; + supporting first-class, multiply invocable continuations + complicates things tremendously for the Lisp implementor. The + ANSI standardizing committee J13, mindful of this, took the view + that it would be better to specify the user-level control + structure (CATCH, UNWIND-PROTECT, and so on) and let + implementors choose whether to build those on top of + continuations or not. + </para> + <para> + If you need to play with continuations, you should use a Scheme + implementation. + </para> + </answer> </qandaentry>

Index: lispfaq/faq.xsl diff -u lispfaq/faq.xsl:1.1 lispfaq/faq.xsl:1.2 --- lispfaq/faq.xsl:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/faq.xsl Mon Mar 22 15:07:41 2004 @@ -13,5 +13,11 @@ <xsl:param name="shade.verbatim" select="1"/> <xsl:param name="css.decoration" select="1"/> <xsl:param name="make.valid.html" select="1"/> + <xsl:param name="html.extra.head.links" select="1"/> + <xsl:param name="chunker.output.encoding" select="'ISO-8859-1'"/> + + <xsl:template name="user.head.content"> + xsl:comment generated HTML; do not edit </xsl:comment> + </xsl:template>

</xsl:stylesheet>

Index: lispfaq/flet.xml diff -u lispfaq/flet.xml:1.1 lispfaq/flet.xml:1.2 --- lispfaq/flet.xml:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/flet.xml Mon Mar 22 15:07:41 2004 @@ -1,13 +1,14 @@ <qandaentry> <question> - <para>Does anyone actually use flet?</para> + <para>Does anyone actually use <code>FLET</code>?</para> </question> <answer> <para> - This question is usually motivated by the existence of labels, - which is a similar form for binding functions, but also allows - mutual recursion between the functions being bound. Given - this, it is perhaps natural to question the utility of flet. + This question is usually motivated by the existence of + <code>LABELS</code>, which is a similar form for binding + functions, but also allows mutual recursion between the + functions being bound. Given this, it is perhaps natural to + question the utility of <code>FLET</code>. </para> <para> However, there are two reasons for using flet: one idiomatic @@ -23,8 +24,10 @@ the behaviour of functions, for instance (a contrived example due to Kent Pitman): </para> - <para>(defun square (x) (* x x))</para> - <para>(flet ((square (x) (make-instance 'square :area (square - x)))) ...)</para> + <programlisting> + (defun square (x) (* x x)) + + (flet ((square (x) (make-instance 'square :area (squarex)))) ...) + </programlisting> </answer> </qandaentry>

Index: lispfaq/freelisp.xml diff -u lispfaq/freelisp.xml:1.1 lispfaq/freelisp.xml:1.2 --- lispfaq/freelisp.xml:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/freelisp.xml Mon Mar 22 15:07:41 2004 @@ -4,8 +4,8 @@ </question> <answer> <para> - There are a number of free (in both the `gratis' and the - `libre' senses) lisp environments: + There are a number of free (in both the `gratis' and the `libre' + senses) lisp environments: </para> <variablelist> <varlistentry>

Index: lispfaq/on-topic.xml diff -u lispfaq/on-topic.xml:1.1 lispfaq/on-topic.xml:1.2 --- lispfaq/on-topic.xml:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/on-topic.xml Mon Mar 22 15:07:41 2004 @@ -15,7 +15,7 @@ the history and evolution of Lisp tends also to be welcomed, or at least tolerated; discussion of non-standard lisps (though generally not Scheme or Emacs Lisp) is also accepted. Though - CLOS (the Common Lisp Object System) has <ulink + <acronym>CLOS</acronym> (the Common Lisp Object System) has <ulink url="news:comp.lang.lisp.clos">its own newsgroup</ulink> it is also part of ANSI CL, and so is a valid topic for discussion. </para>

Index: lispfaq/online.xml diff -u lispfaq/online.xml:1.1 lispfaq/online.xml:1.2 --- lispfaq/online.xml:1.1 Mon Mar 22 13:55:25 2004 +++ lispfaq/online.xml Mon Mar 22 15:07:41 2004 @@ -21,7 +21,7 @@ </listitem> </varlistentry> <varlistentry> - <term><ulink url="http://ww.telent.net/cliki/">CLiki</ulink></term> + <term><ulink url="http://www.cliki.net/">CLiki</ulink></term> <listitem> <para>An on-line Wiki-equivalent with emphasis on Free software written in Common Lisp.</para>