Double compare?

gistfile1.txt

data TTT a = Empty | Two (TTT a) a (TTT a) | Three (TTT a) a (TTT a) a (TTT a)

type Set a = TTT a

empty :: Set a
empty = Empty

member :: Ord a => a -> Set a -> Bool
member x Empty = False
member x (Two l v r) =
    case compare x v of
        LT -> member x l
        EQ -> True
        GT -> member x r
member x (Three l lv m rv r) =
    case compare x lv of
        LT -> member x l
        EQ -> True
        GT -> case compare x rv of
                LT -> member x m
                EQ -> True
                GT -> member x r