[boost] [Optional] Monadic bind

While playing around with boost::optionals I had code like the following struct A { ... int i; ... }; boost::optional a; // do something with 'a' // optional-projection to a::i boost::optional<int> a_i; if(a) a_i = a->i; which seemed quite verbose for something that's rather natural in functional languages: boost::optional is a monadic structure, which lifts a type T by extending it with a new bottom-element (represented by the empty optional<T>), thus it should also have a "bind" and a "map"-equivalent, which could be implemented for instance as as member functions of optional template<class B> auto bind(B&& binder) const -> boost::optional::type> { if(this->is_initialized()) { return std::bind(binder, get())(); } else { return boost::none; } } and template<class B> auto map(B&& f) const -> boost::optional::type> { if(this->is_initialized()) { return std::bind(f, get())(); } else { return boost::none; } } where map lifts f from A->B to optional -> optional< B > and applies 'this' to it. This would allow things like boost::optional a; auto a_i = a.map(&A::i); // "optional-projection"; type of a_i is boost::optional<int> Tobias -- View this message in context: http://boost.2283326.n4.nabble.com/Optional-Monadic-bind-tp4677431.html Sent from the Boost - Dev mailing list archive at Nabble.com.