338 lines
6.6 KiB
HTML
338 lines
6.6 KiB
HTML
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<HTML LANG="en-us"
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>aref | Common Lisp Nova Spec</TITLE
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>Common Lisp Nova Spec</A
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><SPAN CLASS="idx" DATA-KIND="idxref" DATA-TERM="aref"
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></SPAN
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><B
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>aref</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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><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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>aref</B
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> <SPAN CLASS="cmssi"
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>array</SPAN
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> <SPAN CLASS="cmtt"
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>&rest</SPAN
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> <SPAN CLASS="cmssi"
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>subscripts</SPAN
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> <SPAN CLASS="arrow"
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>→</SPAN
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> <SPAN CLASS="cmssi"
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>element</SPAN
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></P
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><P CLASS="j"
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><B
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>(setf (aref</B
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> <SPAN CLASS="cmssi"
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>array</SPAN
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> <SPAN CLASS="cmtt"
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>&rest</SPAN
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> <SPAN CLASS="cmssi"
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>subscripts</SPAN
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><B
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>)</B
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> <SPAN CLASS="cmssi"
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>new-element</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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>array</VAR
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> — an <A HREF="26_1_Glossary.html#array"
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><EM CLASS="term"
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>array</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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>subscripts</VAR
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> — a <A HREF="26_1_Glossary.html#list"
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><EM CLASS="term"
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>list</EM
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></A
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> of <A HREF="26_1_Glossary.html#valid_array_index"
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><EM CLASS="term"
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>valid array indices</EM
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></A
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> for the <VAR CLASS="param"
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>array</VAR
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>. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>element</VAR
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>, <VAR CLASS="param"
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>new-element</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="26_1_Glossary.html#access"
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><EM CLASS="term"
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>Accesses</EM
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></A
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> the <VAR CLASS="param"
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>array</VAR
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> <A HREF="26_1_Glossary.html#element"
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><EM CLASS="term"
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>element</EM
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></A
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> specified by the <VAR CLASS="param"
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>subscripts</VAR
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>. If no <VAR CLASS="param"
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>subscripts</VAR
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> are supplied and <VAR CLASS="param"
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>array</VAR
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> is zero rank, <A HREF="f_aref.html" CLASS="funref"
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><B
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>aref</B
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></A
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> <A HREF="26_1_Glossary.html#access"
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><EM CLASS="term"
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>accesses</EM
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></A
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> the sole element of <VAR CLASS="param"
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>array</VAR
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>. </P
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><P CLASS="j"
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><A HREF="f_aref.html" CLASS="funref"
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><B
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>aref</B
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></A
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> ignores <A HREF="26_1_Glossary.html#fill_pointer"
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><EM CLASS="term"
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>fill pointers</EM
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></A
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>. It is permissible to use <A HREF="f_aref.html" CLASS="funref"
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><B
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>aref</B
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></A
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> to <A HREF="26_1_Glossary.html#access"
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><EM CLASS="term"
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>access</EM
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></A
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> any <VAR CLASS="param"
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>array</VAR
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> <A HREF="26_1_Glossary.html#element"
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><EM CLASS="term"
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>element</EM
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></A
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>, whether <A HREF="26_1_Glossary.html#active"
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><EM CLASS="term"
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>active</EM
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></A
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> or not.</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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><P CLASS="j"
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>If the variable <CODE CLASS="f"
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>foo</CODE
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> names a 3-by-5 array, then the first index could be 0, 1, or 2, and then second index could be 0, 1, 2, 3, or 4. The array elements can be referred to by using the <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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> <A HREF="f_aref.html" CLASS="funref"
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><B
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>aref</B
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></A
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>; for example, <CODE CLASS="f"
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>(aref foo 2 1)</CODE
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> refers to element (2, 1) of the array.</P
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><PRE CLASS="screen"
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>(aref (setq alpha (make-array 4)) 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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> <A HREF="26_1_Glossary.html#implementation-dependent"
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><EM CLASS="term"
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>implementation-dependent</EM
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></A
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>
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(setf (aref alpha 3) 'sirens) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> SIRENS
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(aref alpha 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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> SIRENS
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(aref (setq beta (make-array '(2 4)
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:element-type '(unsigned-byte 2)
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:initial-contents '((0 1 2 3) (3 2 1 0))))
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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
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(setq gamma '(0 2))
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(apply #'aref beta gamma) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 2
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(setf (apply #'aref beta gamma) 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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> 3
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(apply #'aref beta gamma) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 3
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(aref beta 0 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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> 3</PRE
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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_bit.html" CLASS="funref"
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><B
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>bit</B
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></A
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>, <A HREF="f_char.html" CLASS="funref"
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><B
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>char</B
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></A
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>, <A HREF="f_elt.html" CLASS="funref"
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><B
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>elt</B
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></A
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>, <A HREF="f_row-major-aref.html" CLASS="funref"
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><B
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>row-major-aref</B
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></A
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>, <A HREF="f_svref.html" CLASS="funref"
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><B
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>svref</B
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></A
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>, <A HREF="3_2_Compilation.html#sec_3_2_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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>3.2.1</SPAN
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> <SPAN CLASS="cmr"
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>(Compiler</SPAN
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> <SPAN CLASS="cmr"
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>Terminology)</SPAN
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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_adjustable-array-p.html" CLASS="prev"
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>←</A
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><A HREF="f_array-dimension.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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></DIV
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>
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