You might express the algorithm more directly in Haskell, without the reverse calls: bubblesort :: (Ord a) => [a] -> [a] bubblesort [] = [] bubblesort (x0:xs) = case bubble x0 xs of (xs', True) -> bubblesort xs' (xs', False) -> xs' where bubble x1 (x2:xs) | x1 <= x2 = merge x1 False $ bubble x2 xs | otherwise = merge x2 True $ bubble x1 xs bubble x1 [] = ([x1], False) merge x s (xs, s') = (x:xs, s || s') Here, the local bubble function does the job of bubbling a value through, and the merge function handles both rebuilding the new, bubbled list, and the swap flag. The case expression in bubblesort is a direct expression in Haskell of "bubble through the list once, and if we swapped anything, do it again". This version clocks in at about 35% faster than your original. - Mark P.S.: Code and driver Main files can be found here: http://bitbucket.org/mtnviewmark/haskell-playground/src/tip/cafe/ Mark Lentczner http://www.ozonehouse.com/mark/ IRC: mtnviewmark