Defined in The verb object Call signatures Return value A monadic type of the same kind Sequence a recovery computation on the failure path joining its values The callback witnesses the dead state expected s error per alternative when graded or optional s empty state with no arguments and returns a carrier a successful operand passes through bypassing it Recovery branches may return heterogeneous carriers of the same value kind their values join and an error alternative handled by a branch leaves the grade unless re returned In the pipeline form the callback s carrier may also bridge across the expected optional pair on the identity expected the operation is vacuous nothing is asked of the handler not even that it be callable Use through the fn or_else nielbloid or_else_t or_else 1 Binds the dead state returning a carrier x | or_else f constexpr auto operator auto &&fn const > functor<or_else_t decltype fn > 1 Sequence a recovery computation on the failure path joining its values return A functor that will recover the monadic type fn auto && The function to execute on the dead state the error on expected no arguments on optional returning a carrier