Data.Impossible
data Impossible
type ImpossibleM
type ImpossibleT
data ImpossibleM1 t1
data ImpossibleM2 t1 t2
data ImpossibleM3 t1 t2 t3
data ImpossibleM4 t1 t2 t3 t4
data ImpossibleM5 t1 t2 t3 t4 t5
type ImpossibleNat
impossible
impossible'