On 2004-12-16 at 17:00+0100 Henning Thielemann wrote:
imranazad wrote:
Hi,
im not very good with haskell, i barely know the basics, my coursework requires me to genereate a vigenere square....... well anyway at the moment im trying to define a functin all_rotations which for any list returns the list of all its rotations, so far i've made an attempt but it only rotates once....any ideas? i dont want the complete solution just help thats all, much appreciated.
all_rotations :: [a] -> [[a]] all_rotations [] = [] all_rotations (x:xs) = reverse (x:xs) : []
'cycle' the list, then determine all of its suffixes with 'tails' and take the first elements of each list.
playing with inits l `zip` tails l might also be edifying. -- Jón Fairbairn Jon.Fairbairn@cl.cam.ac.uk