sel_id : _ = sel_ids
(tycon, _) = recordSelectorFieldLabel sel_id -- We've failed already if
data_cons = tyConDataCons tycon -- it's not a field label
-- NB: for a data type family, the tycon is the instance tycon
relevant_cons = filter is_relevant data_cons
sel_id : _ = sel_ids
(tycon, _) = recordSelectorFieldLabel sel_id -- We've failed already if
data_cons = tyConDataCons tycon -- it's not a field label
-- NB: for a data type family, the tycon is the instance tycon
relevant_cons = filter is_relevant data_cons