Loopy

Kent M. Pitman wrote:

The ability in loop to do even complex things like:
 
 (loop for x in '(1 2 3 4 5 6 7)
    when (evenp x)
     collect x into evens
    else
     collect x into odds
    finally
     (return (values evens odds)))
 => (2 4 6), (1 3 5 7)

Gauche Scheme

(partition odd? (iota 9)
  ===>
(1 3 5 7)
(0 2 4 6 8)