orderClause :: PersistEntity val => SelectOpt val -> DB.Field
orderClause o = case o of
                  Asc f  -> fieldName f DB.=: ( 1 :: Int)
                  Desc f -> fieldName f DB.=: (-1 :: Int)
                  _      -> error "orderClause: expected Asc or Desc"
orderClause :: PersistEntity val => SelectOpt val -> DB.Field
orderClause o = case o of
                  Asc f  -> fieldName f DB.=: ( 1 :: Int)
                  Desc f -> fieldName f DB.=: (-1 :: Int)
                  _      -> error "orderClause: expected Asc or Desc"
orderClause o = case o of
                  Asc f  -> fieldName f DB.=: ( 1 :: Int)
                  Desc f -> fieldName f DB.=: (-1 :: Int)
                  _      -> error "orderClause: expected Asc or Desc"