(==) (Date weekday dayOfMonth)
       (Date weekday' dayOfMonth') =
      weekday == weekday' && dayOfMonth == dayOfMonth'
(==) (Date weekday dayOfMonth)
       (Date weekday' dayOfMonth') =
      weekday == weekday' && dayOfMonth == dayOfMonth'
(==) (Date weekday dayOfMonth)
       (Date weekday' dayOfMonth') =
      weekday == weekday' && dayOfMonth == dayOfMonth'