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>case, ccase, ecase | 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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>→ <A HREF="5_Data_and_Control_Flow.html"
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> <SPAN CLASS="breadcrumb-item"
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> <SPAN CLASS="breadcrumb-item"
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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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></DIV
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><DIV CLASS="matter"
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><DIV CLASS="com"
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><DIV CLASS="begincom"
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><HR
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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="case, ccase, ecase"
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></SPAN
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><B
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>case, ccase, ecase</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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>Macro</I
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></TD
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></TR
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></TABLE
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><HR
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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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>case</B
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> <SPAN CLASS="cmssi"
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>keyform</SPAN
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> {↓<VAR CLASS="param"
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>normal-clause</VAR
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>}* [↓<VAR CLASS="param"
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>otherwise-clause</VAR
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>] <SPAN CLASS="arrow"
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>→</SPAN
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> {<VAR CLASS="param"
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>result</VAR
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>}*</P
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><P CLASS="j"
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><B
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>ccase</B
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> <SPAN CLASS="cmssi"
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>keyplace</SPAN
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> {↓<VAR CLASS="param"
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>normal-clause</VAR
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>}* <SPAN CLASS="arrow"
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>→</SPAN
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> {<VAR CLASS="param"
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>result</VAR
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>}*</P
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><P CLASS="j"
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><B
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>ecase</B
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> <SPAN CLASS="cmssi"
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>keyform</SPAN
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> {↓<VAR CLASS="param"
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>normal-clause</VAR
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>}* <SPAN CLASS="arrow"
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>→</SPAN
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> {<VAR CLASS="param"
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>result</VAR
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>}*</P
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><TABLE CELLSPACING="0" CELLPADDING="0" RULES="GROUPS" STYLE="margin: 1ex 0"
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><TBODY
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><TR
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE=";padding-right:3px"
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></TD
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE="padding-left:3px;padding-right:3px"
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><VAR CLASS="param"
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>normal-clause</VAR
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><SPAN CLASS="cmssi"
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>::</SPAN
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><SPAN CLASS="cmr"
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>=</SPAN
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></TD
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE="padding-left:3px;"
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> <SPAN CLASS="cmr"
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>(</SPAN
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><SPAN CLASS="cmssi"
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>keys</SPAN
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> <SPAN CLASS="cmsy"
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>{</SPAN
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><VAR CLASS="param"
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>form</VAR
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><SPAN CLASS="cmsy"
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>}</SPAN
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><SPAN CLASS="cmr"
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>*)</SPAN
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></TD
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></TR
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></TBODY
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></TABLE
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><TABLE CELLSPACING="0" CELLPADDING="0" RULES="GROUPS" STYLE="margin: 1ex 0"
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><TBODY
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><TR
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE=";padding-right:3px"
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></TD
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE="padding-left:3px;padding-right:3px"
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><VAR CLASS="param"
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>otherwise-clause</VAR
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><SPAN CLASS="cmssi"
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>::</SPAN
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><SPAN CLASS="cmr"
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>=</SPAN
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></TD
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE="padding-left:3px;"
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> <SPAN CLASS="cmr"
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>(</SPAN
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><SPAN CLASS="cmsy"
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>{</SPAN
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><SPAN CLASS="cmssi"
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>otherwise</SPAN
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> <SPAN CLASS="cmsy"
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>|</SPAN
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> <SPAN CLASS="cmssi"
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>t</SPAN
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><SPAN CLASS="cmsy"
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>}</SPAN
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> <SPAN CLASS="cmsy"
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>{</SPAN
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><VAR CLASS="param"
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>form</VAR
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><SPAN CLASS="cmsy"
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>}</SPAN
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><SPAN CLASS="cmr"
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>*)</SPAN
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></TD
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></TR
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></TBODY
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></TABLE
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><TABLE CELLSPACING="0" CELLPADDING="0" RULES="GROUPS" STYLE="margin: 1ex 0"
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><TBODY
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><TR
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE=";padding-right:3px"
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></TD
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE="padding-left:3px;padding-right:3px"
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><VAR CLASS="param"
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>clause</VAR
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><SPAN CLASS="cmssi"
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>::</SPAN
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><SPAN CLASS="cmr"
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>=</SPAN
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></TD
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE="padding-left:3px;"
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> <SPAN CLASS="cmssi"
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>normal-clause</SPAN
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> <SPAN CLASS="cmsy"
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>|</SPAN
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> <SPAN CLASS="cmssi"
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>otherwise-clause</SPAN
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></TD
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></TR
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></TBODY
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></TABLE
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></DD
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><DT
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><SPAN CLASS="idx" DATA-KIND="idxref" DATA-TERM="otherwise"
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></SPAN
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><SPAN CLASS="idx" DATA-KIND="idxref" DATA-TERM="t"
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></SPAN
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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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>keyform</VAR
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> — a <A HREF="26_1_Glossary.html#form"
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><EM CLASS="term"
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>form</EM
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></A
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>; evaluated to produce a <VAR CLASS="param"
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>test-key</VAR
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>. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>keyplace</VAR
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> — a <A HREF="26_1_Glossary.html#form"
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><EM CLASS="term"
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>form</EM
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></A
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>; evaluated initially to produce a <VAR CLASS="param"
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>test-key</VAR
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>. Possibly also used later as 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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> if no <VAR CLASS="param"
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>keys</VAR
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> match. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>test-key</VAR
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> — an object produced by evaluating <VAR CLASS="param"
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>keyform</VAR
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> or <VAR CLASS="param"
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>keyplace</VAR
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>. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>keys</VAR
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> — a <A HREF="26_1_Glossary.html#designator"
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><EM CLASS="term"
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>designator</EM
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></A
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> for 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#object"
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><EM CLASS="term"
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>objects</EM
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></A
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>. In the case of <A HREF="f_case.html" CLASS="macref"
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><B
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>case</B
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></A
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>, the <A HREF="26_1_Glossary.html#symbol"
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><EM CLASS="term"
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>symbols</EM
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></A
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> <SPAN CLASS="misc"
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><B
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>t</B
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></SPAN
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> and <SPAN CLASS="misc"
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><B
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>otherwise</B
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></SPAN
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> may not be used as the <VAR CLASS="param"
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>keys</VAR
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> <A HREF="26_1_Glossary.html#designator"
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><EM CLASS="term"
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>designator</EM
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></A
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>. To refer to these <A HREF="26_1_Glossary.html#symbol"
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><EM CLASS="term"
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>symbols</EM
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></A
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> by themselves as <VAR CLASS="param"
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>keys</VAR
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>, the designators <CODE CLASS="f"
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>(t)</CODE
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> and <CODE CLASS="f"
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>(otherwise)</CODE
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>, respectively, must be used instead. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>forms</VAR
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> — an <A HREF="26_1_Glossary.html#implicit_progn"
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><EM CLASS="term"
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>implicit progn</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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>results</VAR
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> — the <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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> returned by the <VAR CLASS="param"
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>forms</VAR
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> in the matching <VAR CLASS="param"
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>clause</VAR
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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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>These <A HREF="26_1_Glossary.html#macro"
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><EM CLASS="term"
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>macros</EM
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></A
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> allow the conditional execution of a body of <VAR CLASS="param"
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>forms</VAR
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> in a <VAR CLASS="param"
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>clause</VAR
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> that is selected by matching the <VAR CLASS="param"
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>test-key</VAR
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> on the basis of its identity. </P
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><P CLASS="j"
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>The <VAR CLASS="param"
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>keyform</VAR
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> or <VAR CLASS="param"
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>keyplace</VAR
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> is <A HREF="26_1_Glossary.html#evaluate"
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><EM CLASS="term"
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>evaluated</EM
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></A
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> to produce the <VAR CLASS="param"
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>test-key</VAR
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>. </P
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><P CLASS="j"
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>Each of the <VAR CLASS="param"
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>normal-clauses</VAR
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> is then considered in turn. If the <VAR CLASS="param"
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>test-key</VAR
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> is the <A HREF="26_1_Glossary.html#same"
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><EM CLASS="term"
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>same</EM
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></A
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> as any <A HREF="26_1_Glossary.html#key"
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><EM CLASS="term"
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>key</EM
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></A
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> for that <VAR CLASS="param"
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>clause</VAR
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>, the <VAR CLASS="param"
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>forms</VAR
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> in that <VAR CLASS="param"
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>clause</VAR
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> are <VAR CLASS="param"
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>evaluated</VAR
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> as an <A HREF="26_1_Glossary.html#implicit_progn"
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><EM CLASS="term"
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>implicit progn</EM
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></A
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>, and the <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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> it returns are returned as the value of the <A HREF="f_case.html" CLASS="macref"
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><B
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>case</B
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></A
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>, <A HREF="f_case.html" CLASS="macref"
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><B
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>ccase</B
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></A
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>, or <A HREF="f_case.html" CLASS="macref"
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><B
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>ecase</B
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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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>form</EM
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></A
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>. </P
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><P CLASS="j"
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>These <A HREF="26_1_Glossary.html#macro"
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><EM CLASS="term"
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>macros</EM
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></A
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> differ only in their <EM CLASS="term"
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>behavior</EM
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> when no <VAR CLASS="param"
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>normal-clause</VAR
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> matches; specifically:</P
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><DL
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><DT
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><A HREF="f_case.html" CLASS="macref"
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><B
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>case</B
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></A
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></DT
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><DD
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><P CLASS="j"
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>If no <VAR CLASS="param"
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>normal-clause</VAR
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> matches, and there is an <VAR CLASS="param"
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>otherwise-clause</VAR
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>, then that <VAR CLASS="param"
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|
>otherwise-clause</VAR
|
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> automatically matches; the <VAR CLASS="param"
|
|
>forms</VAR
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> in that <VAR CLASS="param"
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>clause</VAR
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> are <VAR CLASS="param"
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>evaluated</VAR
|
|
> as an <A HREF="26_1_Glossary.html#implicit_progn"
|
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><EM CLASS="term"
|
|
>implicit progn</EM
|
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></A
|
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>, and the <A HREF="26_1_Glossary.html#value"
|
|
><EM CLASS="term"
|
|
>values</EM
|
|
></A
|
|
> it returns are returned as the value of the <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>case</B
|
|
></A
|
|
>. </P
|
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><P CLASS="j"
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>If there is no <VAR CLASS="param"
|
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>otherwise-clause</VAR
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|
>, <A HREF="f_case.html" CLASS="macref"
|
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><B
|
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>case</B
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></A
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> returns <SPAN CLASS="misc"
|
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><B
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>nil</B
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></SPAN
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>.</P
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></DD
|
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><DT
|
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><A HREF="f_case.html" CLASS="macref"
|
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><B
|
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>ccase</B
|
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></A
|
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></DT
|
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><DD
|
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><P CLASS="j"
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>If no <VAR CLASS="param"
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>normal-clause</VAR
|
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> matches, a <A HREF="26_1_Glossary.html#correctable"
|
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><EM CLASS="term"
|
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>correctable</EM
|
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></A
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> <A HREF="26_1_Glossary.html#error"
|
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><EM CLASS="term"
|
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>error</EM
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></A
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> of <A HREF="26_1_Glossary.html#type"
|
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><EM CLASS="term"
|
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>type</EM
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></A
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> <A HREF="t_type-error.html" CLASS="typeref"
|
|
><B
|
|
>type-error</B
|
|
></A
|
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> is signaled. The offending datum is the <VAR CLASS="param"
|
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>test-key</VAR
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> and the expected type is <A HREF="26_1_Glossary.html#type_equivalent"
|
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><EM CLASS="term"
|
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>type equivalent</EM
|
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></A
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> to <CODE CLASS="f"
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>(member <VAR CLASS="param"
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>key1</VAR
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> <VAR CLASS="param"
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>key2</VAR
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> ...)</CODE
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|
>. The <SPAN CLASS="misc"
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><B
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>store-value</B
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></SPAN
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> <A HREF="26_1_Glossary.html#restart"
|
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><EM CLASS="term"
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>restart</EM
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></A
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> can be used to correct the error. </P
|
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><P CLASS="j"
|
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>If the <SPAN CLASS="misc"
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><B
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|
>store-value</B
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></SPAN
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> <A HREF="26_1_Glossary.html#restart"
|
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><EM CLASS="term"
|
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>restart</EM
|
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></A
|
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> is invoked, its <A HREF="26_1_Glossary.html#argument"
|
|
><EM CLASS="term"
|
|
>argument</EM
|
|
></A
|
|
> becomes the new <VAR CLASS="param"
|
|
>test-key</VAR
|
|
>, and is stored in <VAR CLASS="param"
|
|
>keyplace</VAR
|
|
> as if by <CODE CLASS="f"
|
|
>(setf <VAR CLASS="param"
|
|
>keyplace</VAR
|
|
> <VAR CLASS="param"
|
|
>test-key</VAR
|
|
>)</CODE
|
|
>. Then <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ccase</B
|
|
></A
|
|
> starts over, considering each <VAR CLASS="param"
|
|
>clause</VAR
|
|
> anew. </P
|
|
><P CLASS="j"
|
|
>The subforms of <VAR CLASS="param"
|
|
>keyplace</VAR
|
|
> might be evaluated again if none of the cases holds.</P
|
|
></DD
|
|
><DT
|
|
><A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ecase</B
|
|
></A
|
|
></DT
|
|
><DD
|
|
><P CLASS="j"
|
|
>If no <VAR CLASS="param"
|
|
>normal-clause</VAR
|
|
> matches, a <A HREF="26_1_Glossary.html#non-correctable"
|
|
><EM CLASS="term"
|
|
>non-correctable</EM
|
|
></A
|
|
> <A HREF="26_1_Glossary.html#error"
|
|
><EM CLASS="term"
|
|
>error</EM
|
|
></A
|
|
> of <A HREF="26_1_Glossary.html#type"
|
|
><EM CLASS="term"
|
|
>type</EM
|
|
></A
|
|
> <A HREF="t_type-error.html" CLASS="typeref"
|
|
><B
|
|
>type-error</B
|
|
></A
|
|
> is signaled. The offending datum is the <VAR CLASS="param"
|
|
>test-key</VAR
|
|
> and the expected type is <A HREF="26_1_Glossary.html#type_equivalent"
|
|
><EM CLASS="term"
|
|
>type equivalent</EM
|
|
></A
|
|
> to <CODE CLASS="f"
|
|
>(member <VAR CLASS="param"
|
|
>key1</VAR
|
|
> <VAR CLASS="param"
|
|
>key2</VAR
|
|
> ...)</CODE
|
|
>. </P
|
|
><P CLASS="j"
|
|
>Note that in contrast with <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ccase</B
|
|
></A
|
|
>, the caller of <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ecase</B
|
|
></A
|
|
> may rely on the fact that <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ecase</B
|
|
></A
|
|
> does not return if a <VAR CLASS="param"
|
|
>normal-clause</VAR
|
|
> does not match.</P
|
|
></DD
|
|
></DL
|
|
></DD
|
|
><DT
|
|
><B
|
|
>Examples</B
|
|
></DT
|
|
><DD
|
|
><PRE CLASS="screen"
|
|
> (dolist (k '(1 2 3 :four #\v () t 'other))
|
|
(format t "~S "
|
|
(case k ((1 2) 'clause1)
|
|
(3 'clause2)
|
|
(nil 'no-keys-so-never-seen)
|
|
((nil) 'nilslot)
|
|
((:four #\v) 'clause4)
|
|
((t) 'tslot)
|
|
(otherwise 'others))))
|
|
<SPAN CLASS="cmr"
|
|
>⊳</SPAN
|
|
> CLAUSE1 CLAUSE1 CLAUSE2 CLAUSE4 CLAUSE4 NILSLOT TSLOT OTHERS
|
|
<SPAN CLASS="cmsy"
|
|
><SPAN CLASS="arrow"
|
|
>→</SPAN
|
|
></SPAN
|
|
> NIL
|
|
(defun add-em (x) (apply #'+ (mapcar #'decode x)))
|
|
<SPAN CLASS="cmsy"
|
|
><SPAN CLASS="arrow"
|
|
>→</SPAN
|
|
></SPAN
|
|
> ADD-EM
|
|
(defun decode (x)
|
|
(ccase x
|
|
((i uno) 1)
|
|
((ii dos) 2)
|
|
((iii tres) 3)
|
|
((iv cuatro) 4)))
|
|
<SPAN CLASS="cmsy"
|
|
><SPAN CLASS="arrow"
|
|
>→</SPAN
|
|
></SPAN
|
|
> DECODE
|
|
(add-em '(uno iii)) <SPAN CLASS="cmsy"
|
|
><SPAN CLASS="arrow"
|
|
>→</SPAN
|
|
></SPAN
|
|
> 4
|
|
(add-em '(uno iiii))
|
|
<SPAN CLASS="cmr"
|
|
>⊳</SPAN
|
|
> Error: The value of X, IIII, is not I, UNO, II, DOS, III,
|
|
<SPAN CLASS="cmr"
|
|
>⊳</SPAN
|
|
> TRES, IV, or CUATRO.
|
|
<SPAN CLASS="cmr"
|
|
>⊳</SPAN
|
|
> 1: Supply a value to use instead.
|
|
<SPAN CLASS="cmr"
|
|
>⊳</SPAN
|
|
> 2: Return to Lisp Toplevel.
|
|
<SPAN CLASS="cmr"
|
|
>⊳</SPAN
|
|
> Debug> <U CLASS="underline"
|
|
><SPAN CLASS="cmtt"
|
|
>:CONTINUE</SPAN
|
|
> <SPAN CLASS="cmtt"
|
|
>1</SPAN
|
|
></U
|
|
>
|
|
<SPAN CLASS="cmr"
|
|
>⊳</SPAN
|
|
> Value to evaluate and use for X: <U CLASS="underline"
|
|
><SPAN CLASS="cmtt"
|
|
>'IV</SPAN
|
|
></U
|
|
>
|
|
<SPAN CLASS="cmsy"
|
|
><SPAN CLASS="arrow"
|
|
>→</SPAN
|
|
></SPAN
|
|
> 5</PRE
|
|
></DD
|
|
><DT
|
|
><B
|
|
>Side Effects</B
|
|
></DT
|
|
><DD
|
|
><P CLASS="j"
|
|
>The debugger might be entered. If the <SPAN CLASS="misc"
|
|
><B
|
|
>store-value</B
|
|
></SPAN
|
|
> <A HREF="26_1_Glossary.html#restart"
|
|
><EM CLASS="term"
|
|
>restart</EM
|
|
></A
|
|
> is invoked, the <A HREF="26_1_Glossary.html#value"
|
|
><EM CLASS="term"
|
|
>value</EM
|
|
></A
|
|
> of <VAR CLASS="param"
|
|
>keyplace</VAR
|
|
> might be changed.</P
|
|
></DD
|
|
><DT
|
|
><B
|
|
>Affected By</B
|
|
></DT
|
|
><DD
|
|
><P CLASS="j"
|
|
><A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ccase</B
|
|
></A
|
|
> and <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ecase</B
|
|
></A
|
|
>, since they might signal an error, are potentially affected by existing <VAR CLASS="param"
|
|
>handlers</VAR
|
|
> and <A HREF="v_debug-io.html" CLASS="varref"
|
|
><B
|
|
>*debug-io*</B
|
|
></A
|
|
>.</P
|
|
></DD
|
|
><DT
|
|
><B
|
|
>Exceptional Situations</B
|
|
></DT
|
|
><DD
|
|
><P CLASS="j"
|
|
><A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ccase</B
|
|
></A
|
|
> and <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ecase</B
|
|
></A
|
|
> signal an error of <A HREF="26_1_Glossary.html#type"
|
|
><EM CLASS="term"
|
|
>type</EM
|
|
></A
|
|
> <A HREF="t_type-error.html" CLASS="typeref"
|
|
><B
|
|
>type-error</B
|
|
></A
|
|
> if no <VAR CLASS="param"
|
|
>normal-clause</VAR
|
|
> matches.</P
|
|
></DD
|
|
><DT
|
|
><B
|
|
>See Also</B
|
|
></DT
|
|
><DD
|
|
><P CLASS="j"
|
|
><A HREF="f_cond.html" CLASS="macref"
|
|
><B
|
|
>cond</B
|
|
></A
|
|
>, <A HREF="f_typecase.html" CLASS="macref"
|
|
><B
|
|
>typecase</B
|
|
></A
|
|
>, <A HREF="f_setf.html" CLASS="macref"
|
|
><B
|
|
>setf</B
|
|
></A
|
|
>, <A HREF="5_1_Generalized_Reference.html#sec_5_1" CLASS="secref"
|
|
><SPAN CLASS="cmr"
|
|
>Section</SPAN
|
|
> <SPAN CLASS="cmr"
|
|
>5.1</SPAN
|
|
> <SPAN CLASS="cmr"
|
|
>(Generalized</SPAN
|
|
> <SPAN CLASS="cmr"
|
|
>Reference)</SPAN
|
|
></A
|
|
></P
|
|
></DD
|
|
><DT
|
|
><B
|
|
>Notes</B
|
|
></DT
|
|
><DD
|
|
><PRE CLASS="screen"
|
|
>(case <VAR CLASS="param"
|
|
>test-key</VAR
|
|
>
|
|
<SPAN CLASS="cmsy"
|
|
>{</SPAN
|
|
>((<SPAN CLASS="cmsy"
|
|
>{</SPAN
|
|
><VAR CLASS="param"
|
|
>key</VAR
|
|
><SPAN CLASS="cmsy"
|
|
>}</SPAN
|
|
><SPAN CLASS="cmr"
|
|
>*</SPAN
|
|
>) <SPAN CLASS="cmsy"
|
|
>{</SPAN
|
|
><VAR CLASS="param"
|
|
>form</VAR
|
|
><SPAN CLASS="cmsy"
|
|
>}</SPAN
|
|
><SPAN CLASS="cmr"
|
|
>*</SPAN
|
|
>)<SPAN CLASS="cmsy"
|
|
>}</SPAN
|
|
><SPAN CLASS="cmr"
|
|
>*</SPAN
|
|
>)
|
|
<SPAN CLASS="cmsy"
|
|
><SPAN STYLE="font-size:16px;vertical-align:-2px"
|
|
>≡</SPAN
|
|
></SPAN
|
|
>
|
|
(let ((#1=#:g0001 <VAR CLASS="param"
|
|
>test-key</VAR
|
|
>))
|
|
(cond <SPAN CLASS="cmsy"
|
|
>{</SPAN
|
|
>((member #1# '(<SPAN CLASS="cmsy"
|
|
>{</SPAN
|
|
><VAR CLASS="param"
|
|
>key</VAR
|
|
><SPAN CLASS="cmsy"
|
|
>}</SPAN
|
|
><SPAN CLASS="cmr"
|
|
>*</SPAN
|
|
>)) <SPAN CLASS="cmsy"
|
|
>{</SPAN
|
|
><VAR CLASS="param"
|
|
>form</VAR
|
|
><SPAN CLASS="cmsy"
|
|
>}</SPAN
|
|
><SPAN CLASS="cmr"
|
|
>*</SPAN
|
|
>)<SPAN CLASS="cmsy"
|
|
>}</SPAN
|
|
><SPAN CLASS="cmr"
|
|
>*</SPAN
|
|
>))</PRE
|
|
><P CLASS="j"
|
|
>The specific error message used by <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ecase</B
|
|
></A
|
|
> and <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>ccase</B
|
|
></A
|
|
> can vary between implementations. In situations where control of the specific wording of the error message is important, it is better to use <A HREF="f_case.html" CLASS="macref"
|
|
><B
|
|
>case</B
|
|
></A
|
|
> with an <VAR CLASS="param"
|
|
>otherwise-clause</VAR
|
|
> that explicitly signals an error with an appropriate message.</P
|
|
></DD
|
|
></DL
|
|
></DIV
|
|
></DIV
|
|
><DIV CLASS="footer"
|
|
><DIV CLASS="btmnav"
|
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><A HREF="f_when.html" CLASS="prev"
|
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>←</A
|
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><A HREF="f_typecase.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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