XQuery prime number generation

gistfile1.xq

(: simple - http://e-blog-java.blogspot.com/2010/03/determine-prime-numbers-with-xquery.html :)
<primes>
    {
    for $a in (2 to 1000)
     return(
           if(not(some $counter in (2 to ($a - 1)) satisfies $a mod  
             $counter=0)) then {$a}
              else {$a}
           )
    }
</primes>

(: Chris Wallace - http://kitwallace.posterous.com/the-prime-sieve-in-xquery :)
declare function local:sieve($primes,$nums) {  
      if (fn:exists($nums))  
       then   
            let $prime :=  $nums[1]  
            return 
              local:sieve(($primes,$prime), $nums[. mod $prime !=  0])  
       else $primes  
};  

<primes>
{      
local:sieve((),2 to 1000)  
}</primes>  

(: Jirka Kosek ' slow'n'short:' - http://twitter.com/jirkakosek :)
<primes>
{
for $i in (2 to 1000) return   if (every $j in (2 to $i - 1) satisfies $i mod $j ne 0)     then $i     else ()
}
</primes>