( define collectEvens
   ( lambda ( L )
      ( cond ( ( null? L ) '() )
             ( ( even? ( car L ) )
                       ( cons ( car L )
                              ( collectEvens ( cdr L ) )
                              )
                       )
             ( else ( collectEvens ( cdr L ) ) )
             )
      )
   )

( collectEvens '( 1 2 3 4 5 6 7 8 9 10 ) )