-- | For each customer from nation 'n', fetch the date of the 'k' orders
-- with the most lineitems.
topOrdersPerCust' :: Integer -> Text -> Q [(Text, [Day])]
topOrdersPerCust' k n =
    [ tup2 (c_nameQ c) (map o_orderdateQ $ topK k (length . orderItems) (custOrders c))
    | c <- customers
    , c `custFromNation` n
    ]
topOrdersPerCust' :: Integer -> Text -> Q [(Text, [Day])]
topOrdersPerCust' k n =
    [ tup2 (c_nameQ c) (map o_orderdateQ $ topK k (length . orderItems) (custOrders c))
    | c <- customers
    , c `custFromNation` n
    ]
topOrdersPerCust' k n =
    [ tup2 (c_nameQ c) (map o_orderdateQ $ topK k (length . orderItems) (custOrders c))
    | c <- customers
    , c `custFromNation` n
    ]