Fibs in your favourite language

fibs = 1 : zipWith (+) fibs (tail fibs)

>>57
: ackermann ( m n -- r )
{
    { [ over 0 = ] [ nip 1 + ] }
    { [ 2dup [ 0 > ] [ 0 = ] bi* and ] [ drop 1 - 1 ackermann ] }
    { [ 2dup [ 0 > ] both? ] [ dupd 1 - ackermann [ 1 - ] dip ackermann ] }
} cond ;

Better, Fagtorman?