main = take 6 (sieve (from 2)) ;

from n = cons n (from (n+1)) ;

sieve xs = case xs of
		<1> -> nil ;
		<2> p ps -> cons p (sieve (filter (nonMultiple p) ps)) ;

filter predicate xs 
	= case xs of
		<1> -> nil ;
		<2> p ps -> let rest = filter predicate ps 
			    in
			    if (predicate p) (cons p rest) rest ;

nonMultiple p n = ((n/p)*p) ~= n ;

take n xs = if (n==0) 
		nil
		(case xs of
			<1> -> nil ;
			<2> p ps -> cons p (take (n-1) ps))