On Tue, Mar 09, 2010 at 10:35:06PM +0200, Mihai Maruseac wrote: > > myLength xs = foldl addOne 0 xs > where addOne x n = n + 1 Almost, Tim's original addOne is actually addOne x n = x + 1 The difference is that the given solution uses foldr whereas Tim was using foldl. Either one works in this case since + is commutative. -Brent