check_e (HsApp e1 e2) = checkl_e e1 `mplus` checkl_e e2
check_e (NegApp e _) = checkl_e e
check_e (ExplicitList _ es) = checkl_es es
check_e (HsApp e1 e2) = checkl_e e1 `mplus` checkl_e e2
check_e (NegApp e _) = checkl_e e
check_e (ExplicitList _ es) = checkl_es es