Hi
An optimised version of words:
words :: String -> [String] words s = case dropWhile isSpace s of "" -> [] s:ss -> (s:w) : words s'' where (w, s'') = break isSpace ss
Thinking harder, this is an improvement, but not as good as we can get. If s'' is non-empty, then the first character must be a space, which we can drop without testing: words :: String -> [String] words s = case dropWhile isSpace s of "" -> [] s:ss -> (s:w) : words (drop1 s'') where (w, s'') = break isSpace ss drop1 [] = [] drop1 (x:xs) = xs (of course, drop1 = drop 1, but if we're going for maximum efficience :-) ) I think this now ensures that we only test each character once for being a space. Thanks Neil