type Name = String

lowerName :: Name -> Name
lowerName = map toLower

-- then:
lowerName "KELAN" -- evaluates to "kelan"

##</code><code>##

data Piece = Pawn | Rook | Knight | Bishop | Queen | King

-- The type is 'Piece', and to construct an actual value of
-- that type, you use one of the six data constructors.

promotesTo :: Piece -> [Piece]
promotesTo Pawn = [ Rook, Knight, Bishop, Queen ]
promotesTo _ = []

-- then:
promotesTo Pawn -- evaluates to [Rook, Knight, Bishop, Queen]
promotesTo $ head $ promotesTo Pawn -- evaluates to []

##</code><code>##

data Rectangle
    = UnitSquare
    | Square Int
    | Rect Int Int

-- examples of values for each would be:
v1 :: Rectangle
v1 = UnitSquare

v2 :: Rectangle
v2 = Square 3

v3 :: Rectangle
v3 = Rect 5 9