type families in head

1
2
3
4
5
instance (Include (Zone a) (Zone a), Include (Zone a) (Place a)) => Include (Zone a) (Location b a) where
  z `include` Clinic p = z `include` p
  z `include` Home p = z `include` p
  z `include` HomeOffer p = z `include` p
  z `include` AnyOffer p z' = z `include` p || z `include` z'