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<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<TITLE>CLHS: Section 3.4.1.6</TITLE>
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<H2>
3.4.1.6 Examples of Ordinary Lambda Lists</H2> <P>
Here are some examples involving <A REL=DEFINITION HREF="26_glo_o.htm#optional_parameter"><I>optional parameters</I></A> and <A REL=DEFINITION HREF="26_glo_r.htm#rest_parameter"><I>rest parameters</I></A>: <P>
<PRE>
((lambda (a b) (+ a (* b 3))) 4 5) =&gt; 19
((lambda (a &amp;optional (b 2)) (+ a (* b 3))) 4 5) =&gt; 19
((lambda (a &amp;optional (b 2)) (+ a (* b 3))) 4) =&gt; 10
((lambda (&amp;optional (a 2 b) (c 3 d) &amp;rest x) (list a b c d x)))
=&gt; (2 NIL 3 NIL NIL)
((lambda (&amp;optional (a 2 b) (c 3 d) &amp;rest x) (list a b c d x)) 6)
=&gt; (6 T 3 NIL NIL)
((lambda (&amp;optional (a 2 b) (c 3 d) &amp;rest x) (list a b c d x)) 6 3)
=&gt; (6 T 3 T NIL)
((lambda (&amp;optional (a 2 b) (c 3 d) &amp;rest x) (list a b c d x)) 6 3 8)
=&gt; (6 T 3 T (8))
((lambda (&amp;optional (a 2 b) (c 3 d) &amp;rest x) (list a b c d x))
6 3 8 9 10 11)
=&gt; (6 t 3 t (8 9 10 11))
</PRE>
</TT> <P>
Here are some examples involving <A REL=DEFINITION HREF="26_glo_k.htm#keyword_parameter"><I>keyword parameters</I></A>: <P>
<PRE>
((lambda (a b &amp;key c d) (list a b c d)) 1 2) =&gt; (1 2 NIL NIL)
((lambda (a b &amp;key c d) (list a b c d)) 1 2 :c 6) =&gt; (1 2 6 NIL)
((lambda (a b &amp;key c d) (list a b c d)) 1 2 :d 8) =&gt; (1 2 NIL 8)
((lambda (a b &amp;key c d) (list a b c d)) 1 2 :c 6 :d 8) =&gt; (1 2 6 8)
((lambda (a b &amp;key c d) (list a b c d)) 1 2 :d 8 :c 6) =&gt; (1 2 6 8)
((lambda (a b &amp;key c d) (list a b c d)) :a 1 :d 8 :c 6) =&gt; (:a 1 6 8)
((lambda (a b &amp;key c d) (list a b c d)) :a :b :c :d) =&gt; (:a :b :d NIL)
((lambda (a b &amp;key ((:sea c)) d) (list a b c d)) 1 2 :sea 6) =&gt; (1 2 6 NIL)
((lambda (a b &amp;key ((c c)) d) (list a b c d)) 1 2 'c 6) =&gt; (1 2 6 NIL)
</PRE>
</TT> <P>
Here are some examples involving <A REL=DEFINITION HREF="26_glo_o.htm#optional_parameter"><I>optional parameters</I></A>, <A REL=DEFINITION HREF="26_glo_r.htm#rest_parameter"><I>rest parameters</I></A>, and <A REL=DEFINITION HREF="26_glo_k.htm#keyword_parameter"><I>keyword parameters</I></A> together: <P>
<PRE>
((lambda (a &amp;optional (b 3) &amp;rest x &amp;key c (d a))
(list a b c d x)) 1)
=&gt; (1 3 NIL 1 ())
((lambda (a &amp;optional (b 3) &amp;rest x &amp;key c (d a))
(list a b c d x)) 1 2)
=&gt; (1 2 NIL 1 ())
((lambda (a &amp;optional (b 3) &amp;rest x &amp;key c (d a))
(list a b c d x)) :c 7)
=&gt; (:c 7 NIL :c ())
((lambda (a &amp;optional (b 3) &amp;rest x &amp;key c (d a))
(list a b c d x)) 1 6 :c 7)
=&gt; (1 6 7 1 (:c 7))
((lambda (a &amp;optional (b 3) &amp;rest x &amp;key c (d a))
(list a b c d x)) 1 6 :d 8)
=&gt; (1 6 NIL 8 (:d 8))
((lambda (a &amp;optional (b 3) &amp;rest x &amp;key c (d a))
(list a b c d x)) 1 6 :d 8 :c 9 :d 10)
=&gt; (1 6 9 8 (:d 8 :c 9 :d 10))
</PRE>
</TT> <P>
As an example of the use of <TT>&amp;allow-other-keys</TT> and <TT>:allow-other-keys</TT>, consider a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> that takes two named arguments of its own and also accepts additional named arguments to be passed to <A REL=DEFINITION HREF="f_mk_ar.htm#make-array"><B>make-array</B></A>: <P>
<PRE>
(defun array-of-strings (str dims &amp;rest named-pairs
&amp;key (start 0) end &amp;allow-other-keys)
(apply #'make-array dims
:initial-element (subseq str start end)
:allow-other-keys t
named-pairs))
</PRE>
</TT> <P>
This <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> takes a <A REL=DEFINITION HREF="26_glo_s.htm#string"><I>string</I></A> and dimensioning information and returns an <A REL=DEFINITION HREF="26_glo_a.htm#array"><I>array</I></A> of the specified dimensions, each of whose elements is the specified <A REL=DEFINITION HREF="26_glo_s.htm#string"><I>string</I></A>. However, <TT>:start</TT> and <TT>:end</TT> named arguments may be used to specify that a substring of the given <A REL=DEFINITION HREF="26_glo_s.htm#string"><I>string</I></A> should be used. In addition, the presence of <TT>&amp;allow-other-keys</TT> in the <A REL=DEFINITION HREF="26_glo_l.htm#lambda_list"><I>lambda list</I></A> indicates that the caller may supply additional named arguments; the <A REL=DEFINITION HREF="26_glo_r.htm#rest_parameter"><I>rest parameter</I></A> provides access to them. These additional named arguments are passed to <A REL=DEFINITION HREF="f_mk_ar.htm#make-array"><B>make-array</B></A>. The <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> <A REL=DEFINITION HREF="f_mk_ar.htm#make-array"><B>make-array</B></A> normally does not allow the named arguments <TT>:start</TT> and <TT>:end</TT> to be used, and an error should be signaled if such named arguments are supplied to <A REL=DEFINITION HREF="f_mk_ar.htm#make-array"><B>make-array</B></A>. However, the presence in the call to <A REL=DEFINITION HREF="f_mk_ar.htm#make-array"><B>make-array</B></A> of the named argument <TT>:allow-other-keys</TT> with a <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A> value causes any extraneous named arguments, including <TT>:start</TT> and <TT>:end</TT>, to be acceptable and ignored. <P>
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