data Pair f = Pair
  { pairYear  :: Column f Double
  , pairMonth :: Column f Double
  , pairDayofMonth :: Column f Double
  }
  deriving stock (Generic)
  deriving anyclass (Rel8able)

deriving stock instance f ~ Result => Show (Pair f)

getYearMonth :: Query (Pair Expr)
getYearMonth = (\x -> let z = Rel8.fromDay x.dDate
                        in Pair { pairYear       = Rel8.unsafeExtractFromTime "YEAR" z
                                  , pairMonth      = Rel8.unsafeExtractFromTime "MONTH" z
                                  , pairDayofMonth = Rel8.unsafeExtractFromTime "DAY" z}) <$>
                 each daysInMonth