70 lines
6.2 KiB
HTML
70 lines
6.2 KiB
HTML
<!-- 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: Function SUBSETP</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="f_set_ex.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_conses.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_unionc.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<HR>
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<A NAME="subsetp"><I>Function</I> <B>SUBSETP</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>subsetp</B> <I>list-1 list-2 <TT>&key</TT> key test test-not</I> => <I>generalized-boolean</I><P>
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<P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>list-1</I>---a <A REL=DEFINITION HREF="26_glo_p.htm#proper_list"><I>proper list</I></A>. <P>
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<I>list-2</I>---a <A REL=DEFINITION HREF="26_glo_p.htm#proper_list"><I>proper list</I></A>. <P>
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<I>test</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of two <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>test-not</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of two <A REL=DEFINITION HREF="26_glo_a.htm#argument"><I>arguments</I></A> that returns a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<I>key</I>---a <A REL=DEFINITION HREF="26_glo_d.htm#designator"><I>designator</I></A> for a <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> of one argument, or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>generalized-boolean</I>---a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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<A REL=DEFINITION HREF="#subsetp"><B>subsetp</B></A> returns <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A> if every element of <I>list-1</I> <I>matches</I> some element of <I>list-2</I>, and <A REL=DEFINITION HREF="26_glo_f.htm#false"><I>false</I></A> otherwise. <P>
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Whether a list element is the same as another list element is determined by the functions specified by the keyword arguments. The first argument to the <TT>:test</TT> or <TT>:test-not</TT> function is typically part of an element of <I>list-1</I> extracted by the <TT>:key</TT> function; the second argument is typically part of an element of <I>list-2</I> extracted by the <TT>:key</TT> function. <P>
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The argument to the <TT>:key</TT> function is an element of either <I>list-1</I> or <I>list-2</I>; the return value is part of the element of the supplied list element. If <TT>:key</TT> is not supplied or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, the <I>list-1</I> or <I>list-2</I> element itself is supplied to the <TT>:test</TT> or <TT>:test-not</TT> function. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(setq cosmos '(1 "a" (1 2))) => (1 "a" (1 2))
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(subsetp '(1) cosmos) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(subsetp '((1 2)) cosmos) => <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>
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(subsetp '((1 2)) cosmos :test 'equal) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(subsetp '(1 "A") cosmos :test #'equalp) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(subsetp '((1) (2)) '((1) (2))) => <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>
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(subsetp '((1) (2)) '((1) (2)) :key #'car) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B> None.
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<P>
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<P><B>Affected By:</B> None.
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<P>
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<P><B>Exceptional Situations:</B><P>
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<P>
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Should be prepared to signal an error of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <A REL=DEFINITION HREF="e_tp_err.htm#type-error"><B>type-error</B></A> if <I>list-1</I> and <I>list-2</I> are not <A REL=DEFINITION HREF="26_glo_p.htm#proper_list"><I>proper lists</I></A>. <P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=CHILD HREF="03_f.htm">Section 3.6 (Traversal Rules and Side Effects)</A> <P>
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<P><B>Notes:</B><P>
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<P>
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The <TT>:test-not</TT> parameter is deprecated. <P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issues</A>, <I>not part of the specification</I>, apply to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss345.htm">TEST-NOT-IF-NOT:FLUSH-ALL</A><LI> <A REL=CHILD HREF="../Issues/iss240.htm">MAPPING-DESTRUCTIVE-INTERACTION:EXPLICITLY-VAGUE</A><P></UL><HR>
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