buttonBorderF :: Int -> F a b -> F (Bool ⊕ a) b
buttonBorderF border fudget
buttonBorderF
puts a border around a fudget to make it look like a push putton.
Left True
makes the button look pressed.
Left False
makes the button look released.
Right x
propagates x
to the enclosed fudget.
border :: Int
fudget :: F a b
buttonBorderF 5 (labelF "Hello, border")