f :: Int
f x
  | x <- Just x
  , x <- Just x = 
      case x of
          Just x -> 
              e
  | otherwise = do
      e
  where
    x = 
        y

g x = 
    case x of
        a -> 
            x
  where
    foo = 
        case x of
            _ -> do
                launchMissiles
      where
        y = 
            2