Re: [Haskell-beginners] Creating beautiful code: can you make this divide-and-conquer implementation of the "tails" function beautiful?

I'll bite. The source of tails is pretty elegant: tails :: [a] -> [[a]]tails [] = [[]]tails xxs@(_:xs) = xxs : tails xs On Mon, Jun 27, 2011 at 1:30 PM, Costello, Roger L. wrote:

Hi Folks,

Below is a divide-and-conquer implementation of the "tails" function.

Notice the two patterns (x:y:xs) and (x:[]). And notice that (x:y:xs) is used by the "length" function and again by the "splitAt" function. That doesn't seem elegant. Can the function be simplified and made beautiful?

/Roger

tails' :: [a] -> [[a]] tails' (x:y:xs) = map (++zs) (tails' ys) ++ tails' zs where m = length (x:y:xs) n = m `div` 2 (ys,zs) = splitAt n (x:y:xs) tails' (x:[]) = [[x]]

_______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners

-- Michael Xavier http://www.michaelxavier.net