Brief introduction and raffle for a JetBrains license
19:10 Vittorio Romeo (http://vittorioromeo.info) << "Implementing `variant` visitation using lambdas"
The addition of `std::variant` to the upcoming C++17 standard will introduce a "type-safe sum type" to the Standard Library.
Variants model a "choice between types" - they essentially are type-safe "tagged unions".
The interface they expose, however, is often more cumbersome to use than it needs to be: defining exhaustive visitors requires the user to create a class with several `operator()` overloads, or to create a chain of `if constexpr(...)` calls. Both solutions are not very elegant.
After a brief overview of `std::variant` and its usefulness, this talk will focus on the implementation of a "lambda-based in-place visitation" approach, where the user can visit a variant by simply providing a set of lambdas on the spot. This will require implementing a way of overloading arbitrary function objects.
Recursive variant types will then be covered and the "lambda-based" visitation techniques will be applied to them. This will require implementing the "Y combinator" higher-order function to achieve zero-runtime-overhead lambda recursion.
This talk is intended for developers familiar with C++11 and C++14 core language features (lambdas, variadic templates, `auto`, etc...). Prior knowledge of `std::variant` or sum types is not required.
