Hi,

import Data.List

import qualified Data.Set as S

rows :: Ord a => [[a]] -> S.Set [a]

rows = S.fromList

cols :: Ord a => [[a]] -> S.Set [a]

cols = S.fromList . transpose

diagonals :: Ord a => [[a]] -> S.Set [a]

diagonals [] = S.empty

diagonals xss = S.union

( S.fromList $ transpose (zipWith drop [0..] xss) )

( diagonals (map init (tail xss)) )

allWords :: Ord a => [[a]] -> S.Set [a]

allWords xss = S.unions

[ rows xss

, cols xss

, diagonals xss

, diagonals (map reverse xss)

]

Now you can do all sorts of things, since you have the set of all words at hand.

The function you originally wanted, checking the existence of a word can be the following:

search :: Ord a => [a] -> [[a]] -> Bool

search word xss = not $ null [ () | xs <- S.toList (allWords xss), word `isPrefixOf` xs ]

But I suppose a function which removes the found word from the set could be more useful.

Please ask if you have any questions about the above code, I can try to elaborate.

Hope this helps,

Ozgur