<RefEntry id="assoc">
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<?html-filename assoc.html>

<RefMeta>
  <RefEntryTitle>assoc</RefEntryTitle>
  <RefMiscInfo Role="file">dblib.dsl</RefMiscInfo>
</RefMeta>

<RefNameDiv>
  <RefName>assoc</RefName>
  <RefPurpose>Returns the association of an object in an associative list</RefPurpose>
</RefNameDiv>

<RefSynopsisDiv><Title>Synopsis</Title>
<Synopsis>
(assoc obj alist)
</Synopsis>
</RefSynopsisDiv>

<RefSect1><Title>Description</Title>

<para>
Given an associative list, returns the pair that has <literal>obj</literal> as a <literal>car</literal>
or <literal>#f</literal> if no such pair exists.
</para>
<variablelist>
<varlistentry><term>obj</term>
<listitem>
<para>
The associative key to locate.
</para>
</listitem>
</varlistentry>
<varlistentry><term>alist</term>
<listitem>
<para>
The associative list.
</para>
</listitem>
</varlistentry>
</variablelist>

</RefSect1>

<RefSect1><Title>Example</Title>

<para>
<literal>(assoc "a" (("a" "b") ("c" "d")))</literal> returns  <literal>("a" "b")</literal>
</para>


</RefSect1>

<RefSect1><Title>Author</Title>

<para>
Norman Walsh, &lt;ndw@nwalsh.com&gt;
</para>
</RefSect1>
<RefSect1><Title>Source Code</Title>

<ProgramListing>
(define (assoc obj alist)
  ;; Returns the association of an object in an associative list
  (let loop ((al alist))
    (if (null? al)
	#f
	(if (equal? obj (car (car al)))
	    (car al)
	    (loop (cdr al))))))
</ProgramListing>
</RefSect1>

</RefEntry>