maybe monoid

This is the C++ template metaprogramming equivalent of Haskell's Maybe monoid.

General information

• header: <mpllibs/metamonad/maybe.hpp>
• tag of monad: maybe_tag<T> where T is the tag of the value wrapped by just.
• mempty: nothing
• mappend:
  • When both arguments are nothing, the result is nothing
  • When one argument is nothing, the result is the other argument
  • When none of the arguments is nothing, the two values wrapped by just get merged by using mappend on the monoid formed by T values. The result of this gets wrapped by just.

Copyright Abel Sinkovics (abel at elte dot hu) 2011. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt

[up]