Inline caching (memoization) for higher order xquery functions

memoization.xqy

xquery version "1.0-ml";

(: xquery memoization example for use with MarkLogic :)

declare variable $cache := map:map();

declare function local:factorial($n as xs:integer) as xs:integer {
if ($n < 0) then
  (0)  
else if ($n = 0) then
  (1)
else
  $n * local:factorial($n - 1)
};

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 $factorial := xdmp:function(xs:QName("local:factorial"))

let $a:= xdmp:apply($memoize, $factorial, 20)
let $b:= xdmp:apply($memoize, $factorial, 20)
let $c:= xdmp:apply($memoize, $factorial, 20)
let $d:= xdmp:apply($memoize, $factorial, 20)
let $e:= xdmp:apply($memoize, $factorial, 20)
return
$a

neat. Makes me not feel so bad about using maps in functional programming. Is Marklogic's Xquery engine/compiler smart enough to know that its memorization?

Does this work with marklogic without problems