maybe

Synopsis

template <class T>
struct maybe_tag;

struct nothing;
template <class T> struct just;

Description

Algebraic data type with two constructors: just and nothing. It can be used represent an optional value. When it is used for error reporting, just represents success and nothing represents failure.

Header

#include <mpllibs/metamonad/maybe.hpp>

Example

using boost::mpl::equal_to;
using boost::mpl::int_;

struct division_by_zero;

template <class A, class B>
struct divide :
  if_<
    equal_to<A, int_<0>>,
    nothing,
    just<divides<A, B>>
  >
  {};

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

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