378 lines
7.5 KiB
HTML
378 lines
7.5 KiB
HTML
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>values | Common Lisp Nova Spec</TITLE
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>Common Lisp Nova Spec</A
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> <SPAN CLASS="breadcrumb-item"
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> <SPAN CLASS="breadcrumb-item"
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>5.3 Data and Control Flow Dictionary</A
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> <SPAN CLASS="breadcrumb-item"
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>→ <A HREF="f_values.html"
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>values</A
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><A HREF="f_multiple-value-setq.html" CLASS="prev"
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>←</A
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>Apropos </SPAN
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><INPUT ID="apropos" AUTOFOCUS="AUTOFOCUS" PLACEHOLDER="Type here to search" ONINPUT="aproposInput(this);" ONKEYUP="aproposKeyup(event);" ONCHANGE="aproposChange(this);" ONFOCUS="aproposFocus(this);" ONFOCUSOUT="aproposFocusout(this);"
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>→</A
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></DIV
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><DIV CLASS="matter"
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><TABLE WIDTH="100%" CELLSPACING="0" CELLPADDING="0"
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><TR
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><TD ALIGN="LEFT" VALIGN="BASELINE" WIDTH="100%" CLASS="name"
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><SPAN CLASS="idx" DATA-KIND="idxref" DATA-TERM="values"
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></SPAN
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><B
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>values</B
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></TD
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><TD ALIGN="RIGHT" VALIGN="BASELINE" WIDTH="0" NOWRAP="NOWRAP" CLASS="ftype"
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><I
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>Accessor</I
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></TD
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></TR
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></TABLE
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></DIV
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><UL CLASS="subtoc"
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></UL
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><DL
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><DT
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><B
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>Syntax</B
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></DT
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><DD
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><P CLASS="j"
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><B
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>values</B
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> <SPAN CLASS="cmtt"
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>&rest</SPAN
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> <SPAN CLASS="cmssi"
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>object</SPAN
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> <SPAN CLASS="arrow"
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>→</SPAN
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> {<VAR CLASS="param"
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>object</VAR
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>}*</P
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><P CLASS="j"
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><B
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>(setf (values</B
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> <SPAN CLASS="cmtt"
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>&rest</SPAN
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> <SPAN CLASS="cmssi"
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>place</SPAN
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><B
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>)</B
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> <SPAN CLASS="cmssi"
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>new-values</SPAN
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><B
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>)</B
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></P
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></DD
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><DT
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><B
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>Arguments and Values</B
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></DT
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><DD
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><P CLASS="j"
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><VAR CLASS="param"
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>object</VAR
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> — an <A HREF="26_1_Glossary.html#object"
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><EM CLASS="term"
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>object</EM
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></A
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>. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>place</VAR
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> — a <A HREF="26_1_Glossary.html#place"
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><EM CLASS="term"
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>place</EM
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></A
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>. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>new-value</VAR
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> — an <A HREF="26_1_Glossary.html#object"
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><EM CLASS="term"
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>object</EM
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></A
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>.</P
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></DD
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><DT
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><B
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>Description</B
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></DT
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><DD
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><P CLASS="j"
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><A HREF="f_values.html" CLASS="funref"
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><B
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>values</B
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></A
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> returns the <VAR CLASS="param"
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>objects</VAR
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> as <A HREF="26_1_Glossary.html#multiple_values"
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><EM CLASS="term"
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>multiple values</EM
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></A
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><SPAN CLASS="meaning"
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><SUB CLASS="sub"
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><SPAN CLASS="cmr"
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>2</SPAN
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></SUB
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></SPAN
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>. </P
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><P CLASS="j"
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><A HREF="f_setf.html" CLASS="macref"
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><B
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>setf</B
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></A
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> of <A HREF="f_values.html" CLASS="funref"
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><B
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>values</B
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></A
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> is used to store the <A HREF="26_1_Glossary.html#multiple_values"
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><EM CLASS="term"
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>multiple values</EM
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></A
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><SPAN CLASS="meaning"
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><SUB CLASS="sub"
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><SPAN CLASS="cmr"
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>2</SPAN
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></SUB
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></SPAN
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> <VAR CLASS="param"
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>new-values</VAR
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> into the <VAR CLASS="param"
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>places</VAR
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>. See <A HREF="5_1_Generalized_Reference.html#sec_5_1_2_3" CLASS="secref"
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><SPAN CLASS="cmr"
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>Section</SPAN
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> <SPAN CLASS="cmr"
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>5.1.2.3</SPAN
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> <SPAN CLASS="cmr"
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>(VALUES</SPAN
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> <SPAN CLASS="cmr"
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>Forms</SPAN
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> <SPAN CLASS="cmr"
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>as</SPAN
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> <SPAN CLASS="cmr"
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>Places)</SPAN
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></A
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>.</P
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></DD
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><DT
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><B
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>Examples</B
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></DT
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><DD
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><PRE CLASS="screen"
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> (values) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> <SPAN CLASS="cmsy"
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>⟨</SPAN
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><I
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>no</I
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> <A HREF="26_1_Glossary.html#value"
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><EM CLASS="term"
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>values</EM
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></A
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><SPAN CLASS="cmsy"
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>⟩</SPAN
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>
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(values 1) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 1
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(values 1 2) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 1, 2
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(values 1 2 3) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 1, 2, 3
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(values (values 1 2 3) 4 5) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 1, 4, 5
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(defun polar (x y)
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(values (sqrt (+ (* x x) (* y y))) (atan y x))) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> POLAR
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(multiple-value-bind (r theta) (polar 3.0 4.0)
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(vector r theta))
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<SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> #(5.0 0.927295)</PRE
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><P CLASS="j"
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>Sometimes it is desirable to indicate explicitly that a function returns exactly one value. For example, the function</P
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><PRE CLASS="screen"
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>(defun foo (x y)
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(floor (+ x y) y)) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> FOO</PRE
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><P CLASS="j"
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>returns two values because <A HREF="f_floor.html" CLASS="funref"
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><B
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>floor</B
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></A
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> returns two values. It may be that the second value makes no sense, or that for efficiency reasons it is desired not to compute the second value. <A HREF="f_values.html" CLASS="funref"
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><B
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>values</B
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></A
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> is the standard idiom for indicating that only one value is to be returned:</P
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><PRE CLASS="screen"
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>(defun foo (x y)
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(values (floor (+ x y) y))) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> FOO</PRE
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><P CLASS="j"
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>This works because <A HREF="f_values.html" CLASS="funref"
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><B
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>values</B
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></A
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> returns exactly one value for each of <VAR CLASS="param"
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>args</VAR
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>; as for any function call, if any of <VAR CLASS="param"
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>args</VAR
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> produces more than one value, all but the first are discarded.</P
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></DD
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><DT
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><B
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>See Also</B
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></DT
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><DD
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><P CLASS="j"
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><A HREF="f_values-list.html" CLASS="funref"
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><B
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>values-list</B
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></A
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>, <A HREF="f_multiple-value-bind.html" CLASS="macref"
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><B
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>multiple-value-bind</B
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></A
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>, <A HREF="v_multiple-values-limit.html" CLASS="conref"
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><B
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>multiple-values-limit</B
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></A
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>, <A HREF="3_1_Evaluation.html#sec_3_1" CLASS="secref"
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><SPAN CLASS="cmr"
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>Section</SPAN
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> <SPAN CLASS="cmr"
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>3.1</SPAN
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> <SPAN CLASS="cmr"
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>(Evaluation)</SPAN
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></A
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></P
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></DD
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><DT
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><B
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>Notes</B
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></DT
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><DD
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><P CLASS="j"
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>Since <A HREF="f_values.html" CLASS="funref"
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><B
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>values</B
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></A
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> is a <A HREF="26_1_Glossary.html#function"
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><EM CLASS="term"
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>function</EM
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></A
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>, not a <A HREF="26_1_Glossary.html#macro"
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><EM CLASS="term"
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>macro</EM
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></A
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> or <A HREF="26_1_Glossary.html#special_form"
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><EM CLASS="term"
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>special form</EM
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></A
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>, it receives as <A HREF="26_1_Glossary.html#argument"
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><EM CLASS="term"
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>arguments</EM
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></A
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> only the <A HREF="26_1_Glossary.html#primary_value"
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><EM CLASS="term"
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>primary values</EM
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></A
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> of its <A HREF="26_1_Glossary.html#argument"
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><EM CLASS="term"
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>argument</EM
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></A
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> <A HREF="26_1_Glossary.html#form"
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><EM CLASS="term"
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>forms</EM
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></A
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>.</P
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></DD
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></DL
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></DIV
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></DIV
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><DIV CLASS="footer"
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><DIV CLASS="btmnav"
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><A HREF="f_multiple-value-setq.html" CLASS="prev"
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>←</A
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><A HREF="f_values-list.html" CLASS="next"
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>→</A
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></DIV
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><DIV CLASS="trail"
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>Conversion to HTML copyright 2023 by Gilbert Baumann</DIV
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