conDetailsFVs (PrefixCon btys) = plusFVs (map bangTyFVs btys)
conDetailsFVs (InfixCon bty1 bty2) = bangTyFVs bty1 `plusFV` bangTyFVs bty2
conDetailsFVs (PrefixCon btys) = plusFVs (map bangTyFVs btys)
conDetailsFVs (InfixCon bty1 bty2) = bangTyFVs bty1 `plusFV` bangTyFVs bty2