module Exercise_4 where

{-H4.1.10-}
editDistance :: Eq a => [a] -> [a] -> Int
editDistance _ [] = 0
editDistance [] _ = 0
editDistance a b = editDistance' (length a) (length b)
                   where editDistance' 0 0 = 0
                         editDistance' i 0 = i
                         editDistance' 0 j = j
                         editDistance' i j = min (min (if a!!(i-1) == b!!(j-1) then editDistance' (i-1) (j-1) else editDistance' (i-1) (j-1) +1) (if i > 1 && j > 1 && a!!(i-1) == b!!(j-2) && a!!(i-2) == b!!(j-1) then editDistance' (i-2) (j-2) +1 else 100))
                                             (min (if i > 0 then editDistance' (i-1) j +1 else 100) (if j > 0 then editDistance' i (j-1) +1 else 100))
  {-looks awful sorry-}                                        


{-H4.1.11-}
{-WETT-}
spellCorrect :: [String] -> [String] -> [[String]]
spellCorrect [] _ = []
spellCorrect _ [] = []
spellCorrect d (x:xs) = [y |y<-d,editDistance x y == minEdit] :spellCorrect d xs
                        where minEdit = minimum[editDistance x y|y<-d] 
{-TTEW-}