memoization - a step ahead of recursion

gistfile1.txt

http://docs.marklogic.com/guide/performance/perftune -- performance tuning

xquery version "1.0-ml";
 
(: xquery memoization example for use with MarkLogic :)
 
declare variable $cache := map:map();
 

declare function local:books-by-author($a as element(b:author))
as element(b:title)*

{
for $b in doc("books.xml")/b:bib/b:book 
where some $ba in $b/b:author satisfies

($ba/b:last=$l and $ba/b:first=$f)
order by $b/b:title
return $b/b:title

}

 
declare function local:memoize($func,$var){
 
let $key   := xdmp:md5(concat($func,string($var)))
return
if(map:get($cache,$key)) then
 (map:get($cache,$key), xdmp:log('cache hit'))
else
  let $result := xdmp:apply($func,$var)
  return
      (map:put($cache,$key,$result), $result)
};
 
let $memoize := xdmp:function(xs:QName("local:memoize"))
let $books-by-author := xdmp:function(xs:QName("local:books-by-author"))
 

let $f:= xdmp:apply($memoize, $books-by-author, "Bach")
return
$a