open list monad io char

:::IO

null = foldr (\_ _ -> false) true

mapM_ f = foldr ((>>-) << f) (return ())

abc _ [] = [[]]
abc blocks (c::cs) =
  [b::ans \\ b <- blocks | c `elem` b, ans <- abc (delete b blocks) cs]

blocks = ["BO", "XK", "DQ", "CP", "NA", "GT", "RE", "TG", "QD", "FS",
          "JW", "HU", "VI", "AN", "OB", "ER", "FS", "LY", "PC", "ZM"]

mapM_ (\w -> putLn (w, not << null $ abc blocks (map char.upper w)))
  ["", "A", "BARK", "BoOK", "TrEAT", "COmMoN", "SQUAD", "conFUsE"]