What does it mean?

(:).(++) :: [a] -> [[a] -> [a]] -> [[a] -> [a]]

http://www.google.com/search?q=%22(:).(%2B%2B)+::+[a]+-%3E+[[a]+-%3E+[a]]+-%3E+[[a]+-%3E+[a]]%22

The function (:) . (++) is equivalent to \f fs -> (f ++) : fs. Do you see why?

Maybe you meant to liftM2 ((:) .)?

I was confused by the use of [[a] -> [a]] rather than [([a] -> [a])]. In retrospect the second is nonsensical, because the parens don't provide an informative grouping. I was too accustomed to the most common syntax and forgot the semantics.

Anyway, thanks for answering.

>>3
YOU HELPED HIM!

>>3
liftM2 ((:) .)
I don't see how that's remotely useful. (flip (:) .) . (++) is better.

>>8
I am going to murder you with my penis.

Are the imageboards down again?