595 lines
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HTML
595 lines
13 KiB
HTML
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<HTML LANG="en-us"
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>function | 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="4_Types_and_Classes.html"
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>4. Types and Classes</A
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> <SPAN CLASS="breadcrumb-item"
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>→ <A HREF="4_4_Types_and_Classes_Dictionary.html"
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>4.4 Types and Classes Dictionary</A
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> <SPAN CLASS="breadcrumb-item"
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>function</A
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>←</A
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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="function"
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></SPAN
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><B
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>function</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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>System</I
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> <I
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>Class</I
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></TD
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></TABLE
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></DIV
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></UL
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><DL
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><DT
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><B
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>Class Precedence List</B
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></DT
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><DD
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><P CLASS="j"
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><A HREF="t_function.html" CLASS="typeref"
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><B
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>function</B
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></A
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>, <A HREF="t_t.html" CLASS="typeref"
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><B
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>t</B
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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 <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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> is 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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> that represents code to be executed when an appropriate number of arguments is supplied. 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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> is produced by the <A HREF="f_function.html" CLASS="specref"
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><B
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>function</B
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></A
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> <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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>, 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_coerce.html" CLASS="funref"
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><B
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>coerce</B
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></A
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>, or 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_compile.html" CLASS="funref"
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><B
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>compile</B
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></A
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>. 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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> can be directly invoked by using it as the first argument to <A HREF="f_funcall.html" CLASS="funref"
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><B
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>funcall</B
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></A
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>, <A HREF="f_apply.html" CLASS="funref"
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><B
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>apply</B
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></A
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>, or <A HREF="f_multiple-value-call.html" CLASS="specref"
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><B
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>multiple-value-call</B
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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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>Compound Type Specifier Kind</B
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></DT
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><DD
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><P CLASS="j"
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>Specializing.</P
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></DD
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><DT
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><B
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>Compound Type Specifier Syntax</B
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></DT
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><DD
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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=";"
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><SPAN CLASS="cmtt"
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>(function</SPAN
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> <SPAN CLASS="cmtt"
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>[</SPAN
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><SPAN CLASS="cmssi"
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>arg-typespec</SPAN
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> <SPAN CLASS="cmr"
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>[</SPAN
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><SPAN CLASS="cmssi"
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>value-typespec</SPAN
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><SPAN CLASS="cmr"
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>]</SPAN
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><SPAN CLASS="cmtt"
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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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>arg-typespec</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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><VAR CLASS="param"
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>typespec</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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><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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></TD
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE="padding-left:3px;"
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> <SPAN CLASS="cmtt"
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>[&optional</SPAN
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> <SPAN CLASS="cmsy"
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>{</SPAN
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><VAR CLASS="param"
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>typespec</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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><SPAN CLASS="cmtt"
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>]</SPAN
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></TD
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></TR
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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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></TD
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE="padding-left:3px;"
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> <SPAN CLASS="cmtt"
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>[&rest</SPAN
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> <VAR CLASS="param"
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>typespec</VAR
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><SPAN CLASS="cmtt"
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>]</SPAN
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></TD
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></TR
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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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></TD
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><TD ALIGN="LEFT" VALIGN="BASELINE" STYLE="padding-left:3px;"
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> <SPAN CLASS="cmtt"
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>[&key</SPAN
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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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><SPAN CLASS="cmssi"
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>keyword</SPAN
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> <SPAN CLASS="cmssi"
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>typespec</SPAN
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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="cmr"
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>*</SPAN
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><SPAN CLASS="cmtt"
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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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></DD
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><DT
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><B
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>Compound Type Specifier Arguments</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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>typespec</VAR
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> — a <A HREF="26_1_Glossary.html#type_specifier"
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><EM CLASS="term"
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>type specifier</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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>value-typespec</VAR
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> — a <A HREF="26_1_Glossary.html#type_specifier"
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><EM CLASS="term"
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>type specifier</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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>Compound Type Specifier Description</B
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></DT
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><DD
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><P CLASS="j"
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>The list form of the <A HREF="t_function.html" CLASS="typeref"
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><B
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>function</B
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></A
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> <EM CLASS="term"
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>type-specifier</EM
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> can be used only for declaration and not for discrimination. Every element of this <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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> 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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> that accepts arguments of the types specified by the <VAR CLASS="param"
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>argj-types</VAR
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> and returns values that are members of the <A HREF="26_1_Glossary.html#type"
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><EM CLASS="term"
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>types</EM
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></A
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> specified by <VAR CLASS="param"
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>value-type</VAR
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>. The <SPAN CLASS="keyref"
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><B
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>&optional</B
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></SPAN
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>, <SPAN CLASS="keyref"
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><B
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>&rest</B
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></SPAN
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>, <SPAN CLASS="keyref"
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><B
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>&key</B
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></SPAN
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>, and <SPAN CLASS="keyref"
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><B
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>&allow-other-keys</B
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></SPAN
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> markers can appear in the list of argument types. The <A HREF="26_1_Glossary.html#type_specifier"
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><EM CLASS="term"
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>type specifier</EM
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></A
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> provided with <SPAN CLASS="keyref"
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><B
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>&rest</B
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></SPAN
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> is the <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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> of each actual argument, not the <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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> of the corresponding variable. </P
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><P CLASS="j"
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>The <SPAN CLASS="keyref"
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><B
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>&key</B
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></SPAN
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> parameters should be supplied as lists of the form <SPAN CLASS="cmtt"
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|
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>(</SPAN
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><VAR CLASS="param"
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>keyword</VAR
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> <VAR CLASS="param"
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>type</VAR
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><SPAN CLASS="cmtt"
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>)</SPAN
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||
|
|
>. The <VAR CLASS="param"
|
||
|
|
>keyword</VAR
|
||
|
|
> must be a valid keyword-name symbol as must be supplied in the actual arguments of a call. This is usually a <A HREF="26_1_Glossary.html#symbol"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>symbol</EM
|
||
|
|
></A
|
||
|
|
> in the <SPAN CLASS="packref"
|
||
|
|
><SPAN CLASS="cmtt"
|
||
|
|
>KEYWORD</SPAN
|
||
|
|
></SPAN
|
||
|
|
> <A HREF="26_1_Glossary.html#package"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>package</EM
|
||
|
|
></A
|
||
|
|
> but can be any <A HREF="26_1_Glossary.html#symbol"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>symbol</EM
|
||
|
|
></A
|
||
|
|
>. When <SPAN CLASS="keyref"
|
||
|
|
><B
|
||
|
|
>&key</B
|
||
|
|
></SPAN
|
||
|
|
> is given in a <SPAN CLASS="declref"
|
||
|
|
><B
|
||
|
|
>function</B
|
||
|
|
></SPAN
|
||
|
|
> <A HREF="26_1_Glossary.html#type_specifier"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>type specifier</EM
|
||
|
|
></A
|
||
|
|
> <A HREF="26_1_Glossary.html#lambda_list"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>lambda list</EM
|
||
|
|
></A
|
||
|
|
>, the <A HREF="26_1_Glossary.html#keyword_parameter"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>keyword parameters</EM
|
||
|
|
></A
|
||
|
|
> given are exhaustive unless <SPAN CLASS="keyref"
|
||
|
|
><B
|
||
|
|
>&allow-other-keys</B
|
||
|
|
></SPAN
|
||
|
|
> is also present. <SPAN CLASS="keyref"
|
||
|
|
><B
|
||
|
|
>&allow-other-keys</B
|
||
|
|
></SPAN
|
||
|
|
> is an indication that other keyword arguments might actually be supplied and, if supplied, can be used. For example, the <A HREF="26_1_Glossary.html#type"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>type</EM
|
||
|
|
></A
|
||
|
|
> of the <A HREF="26_1_Glossary.html#function"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>function</EM
|
||
|
|
></A
|
||
|
|
> <A HREF="f_make-list.html" CLASS="funref"
|
||
|
|
><B
|
||
|
|
>make-list</B
|
||
|
|
></A
|
||
|
|
> could be declared as follows:</P
|
||
|
|
><PRE CLASS="screen"
|
||
|
|
>(function ((integer 0) &key (:initial-element t)) list)</PRE
|
||
|
|
><P CLASS="j"
|
||
|
|
>The <VAR CLASS="param"
|
||
|
|
>value-type</VAR
|
||
|
|
> can be a <SPAN CLASS="declref"
|
||
|
|
><B
|
||
|
|
>values</B
|
||
|
|
></SPAN
|
||
|
|
> <A HREF="26_1_Glossary.html#type_specifier"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>type specifier</EM
|
||
|
|
></A
|
||
|
|
> in order to indicate the <A HREF="26_1_Glossary.html#type"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>types</EM
|
||
|
|
></A
|
||
|
|
> of <A HREF="26_1_Glossary.html#multiple_values"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>multiple values</EM
|
||
|
|
></A
|
||
|
|
>. </P
|
||
|
|
><P CLASS="j"
|
||
|
|
>Consider a declaration of the following form:</P
|
||
|
|
><PRE CLASS="screen"
|
||
|
|
>(ftype (function (arg0-type arg1-type ...) val-type) f))</PRE
|
||
|
|
><P CLASS="j"
|
||
|
|
>Any <A HREF="26_1_Glossary.html#form"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>form</EM
|
||
|
|
></A
|
||
|
|
> <SPAN CLASS="cmtt"
|
||
|
|
>(f</SPAN
|
||
|
|
> <SPAN CLASS="cmtt"
|
||
|
|
>arg0</SPAN
|
||
|
|
> <SPAN CLASS="cmtt"
|
||
|
|
>arg1</SPAN
|
||
|
|
> <SPAN CLASS="cmtt"
|
||
|
|
>...)</SPAN
|
||
|
|
> within the scope of that declaration is equivalent to the following:</P
|
||
|
|
><PRE CLASS="screen"
|
||
|
|
>(the val-type (f (the arg0-type arg0) (the arg1-type arg1) ...))</PRE
|
||
|
|
><P CLASS="j"
|
||
|
|
>That is, the consequences are undefined if any of the arguments are not of the specified <A HREF="26_1_Glossary.html#type"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>types</EM
|
||
|
|
></A
|
||
|
|
> or the result is not of the specified <A HREF="26_1_Glossary.html#type"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>type</EM
|
||
|
|
></A
|
||
|
|
>. In particular, if any argument is not of the correct <A HREF="26_1_Glossary.html#type"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>type</EM
|
||
|
|
></A
|
||
|
|
>, the result is not guaranteed to be of the specified <A HREF="26_1_Glossary.html#type"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>type</EM
|
||
|
|
></A
|
||
|
|
>. </P
|
||
|
|
><P CLASS="j"
|
||
|
|
>Thus, an <A HREF="m_ftype.html" CLASS="declref"
|
||
|
|
><B
|
||
|
|
>ftype</B
|
||
|
|
></A
|
||
|
|
> declaration for a <A HREF="26_1_Glossary.html#function"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>function</EM
|
||
|
|
></A
|
||
|
|
> describes <A HREF="26_1_Glossary.html#call"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>calls</EM
|
||
|
|
></A
|
||
|
|
> to the <A HREF="26_1_Glossary.html#function"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>function</EM
|
||
|
|
></A
|
||
|
|
>, not the actual definition of the <A HREF="26_1_Glossary.html#function"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>function</EM
|
||
|
|
></A
|
||
|
|
>. </P
|
||
|
|
><P CLASS="j"
|
||
|
|
>Consider a declaration of the following form:</P
|
||
|
|
><PRE CLASS="screen"
|
||
|
|
>(type (function (arg0-type arg1-type ...) val-type) fn-valued-variable)</PRE
|
||
|
|
><P CLASS="j"
|
||
|
|
>This declaration has the interpretation that, within the scope of the declaration, the consequences are unspecified if the value of <SPAN CLASS="cmtt"
|
||
|
|
>fn-valued-variable</SPAN
|
||
|
|
> is called with arguments not of the specified <A HREF="26_1_Glossary.html#type"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>types</EM
|
||
|
|
></A
|
||
|
|
>; the value resulting from a valid call will be of type <SPAN CLASS="cmtt"
|
||
|
|
>val-type</SPAN
|
||
|
|
>. </P
|
||
|
|
><P CLASS="j"
|
||
|
|
>As with variable type declarations, nested declarations imply intersections of <A HREF="26_1_Glossary.html#type"
|
||
|
|
><EM CLASS="term"
|
||
|
|
>types</EM
|
||
|
|
></A
|
||
|
|
>, as follows:</P
|
||
|
|
><UL
|
||
|
|
><LI
|
||
|
|
><P CLASS="j"
|
||
|
|
>Consider the following two declarations of <A HREF="m_ftype.html" CLASS="declref"
|
||
|
|
><B
|
||
|
|
>ftype</B
|
||
|
|
></A
|
||
|
|
>:</P
|
||
|
|
><PRE CLASS="screen"
|
||
|
|
>(ftype (function (arg0-type1 arg1-type1 ...) val-type1) f))</PRE
|
||
|
|
><P CLASS="j"
|
||
|
|
>and</P
|
||
|
|
><PRE CLASS="screen"
|
||
|
|
>(ftype (function (arg0-type2 arg1-type2 ...) val-type2) f))</PRE
|
||
|
|
><P CLASS="j"
|
||
|
|
>If both these declarations are in effect, then within the shared scope of the declarations, calls to <SPAN CLASS="cmtt"
|
||
|
|
>f</SPAN
|
||
|
|
> can be treated as if <SPAN CLASS="cmtt"
|
||
|
|
>f</SPAN
|
||
|
|
> were declared as follows:</P
|
||
|
|
><PRE CLASS="screen"
|
||
|
|
>(ftype (function ((and arg0-type1 arg0-type2) (and arg1-type1 arg1-type2 ...) ...)
|
||
|
|
(and val-type1 val-type2))
|
||
|
|
f))</PRE
|
||
|
|
><P CLASS="j"
|
||
|
|
>It is permitted to ignore one or all of the <A HREF="m_ftype.html" CLASS="declref"
|
||
|
|
><B
|
||
|
|
>ftype</B
|
||
|
|
></A
|
||
|
|
> declarations in force.</P
|
||
|
|
></LI
|
||
|
|
><LI
|
||
|
|
><P CLASS="j"
|
||
|
|
>If two (or more) type declarations are in effect for a variable, and they are both <SPAN CLASS="cmtt"
|
||
|
|
>function</SPAN
|
||
|
|
> declarations, the declarations combine similarly.</P
|
||
|
|
></LI
|
||
|
|
></UL
|
||
|
|
></DD
|
||
|
|
></DL
|
||
|
|
></DIV
|
||
|
|
></DIV
|
||
|
|
><DIV CLASS="footer"
|
||
|
|
><DIV CLASS="btmnav"
|
||
|
|
><A HREF="t_boolean.html" CLASS="prev"
|
||
|
|
>←</A
|
||
|
|
><A HREF="t_compiled-function.html" CLASS="next"
|
||
|
|
>→</A
|
||
|
|
></DIV
|
||
|
|
><DIV CLASS="trail"
|
||
|
|
>Conversion to HTML copyright 2023 by Gilbert Baumann</DIV
|
||
|
|
></DIV
|
||
|
|
></DIV
|
||
|
|
><SCRIPT
|
||
|
|
>domReady();</SCRIPT
|
||
|
|
></BODY
|
||
|
|
></HTML
|
||
|
|
>
|