<RefEntry id="node-list-filter-by-gi">
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<?html-filename node-list-filter-by-gi.html>

<RefMeta>
  <RefEntryTitle>node-list-filter-by-gi</RefEntryTitle>
  <RefMiscInfo Role="file">dblib.dsl</RefMiscInfo>
</RefMeta>

<RefNameDiv>
  <RefName>node-list-filter-by-gi</RefName>
  <RefPurpose>Returns selected elements from a node list</RefPurpose>
</RefNameDiv>

<RefSynopsisDiv><Title>Synopsis</Title>
<Synopsis>
(node-list-filter-by-gi nodelist gilist)
</Synopsis>
</RefSynopsisDiv>

<RefSect1><Title>Description</Title>

<para>
Returns a node list containing all the nodes from <literal>nodelist</literal> whose
GIs are members of <literal>gilist</literal>.  The order of nodes in the node list
is preserved.</para>


</RefSect1>

<RefSect1><Title>Author</Title>

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

<ProgramListing>
(define (node-list-filter-by-gi nodelist gilist)
  ;; Returns selected elements from a node list
  (let loop ((result (empty-node-list)) (nl nodelist))
    (if (node-list-empty? nl)
	result
	(if (member (gi (node-list-first nl)) gilist)
	    (loop (node-list result (node-list-first nl)) 
		  (node-list-rest nl))
	    (loop result (node-list-rest nl))))))
</ProgramListing>
</RefSect1>

</RefEntry>
