C + + implemented a Y-function _c language that can write recursive lambda

Recently learn c++11 variadic template argument, finally can get rid of the Fpmacro template to copy a lot of code of practice, good fun. The main function of this example uses lambda to write a recursive computational function of a Fibonacci sequence. Unlike in the past, with the help of the Y function, this lambda expression is able to see itself successfully and then recursively called. Of course this still needs to use the ordinary C + + recursive return realization, is not λ-calculus that tall on the Y Combinator.

#include <functional> #include <memory> #include <iostream> #include <string> using namespace St

D Template<typename TResult, TypeName ... Targs> class Ybuilder {Private:function<tresult (Function<tresult (Targs ...) ", Targs ...)

> Partiallambda; Public:ybuilder (Function<tresult) (Function<tresult (Targs ...) ", Targs ...) > _partiallambda):p artiallambda (_PARTIALLAMBDA) {} TResult operator () (Targs ... args) const {RET

      Urn Partiallambda ([this] (Targs ... args) {return this->operator () (args ...);

  }, args ...);

}

};

  Template<typename tmethod> struct Partiallambdatyperetriver {typedef void Functiontype;

  typedef void Lambdatype;

typedef void Ybuildertype;

}; Template<typename Tclass, TypeName TResult, TypeName ... targs> struct Partiallambdatyperetriver<tresult (__thiscall tclass::*) (Function<tresult (TArgs ...) ", Targs ...) > {typedef TResult Functiontype (Targs ...); typedef TResult LAMBDATYPE (Function<tresult (Targs ...)

  ", Targs ...);

typedef ybuilder<tresult, targs...> Ybuildertype;


}; Template<typename Tclass, TypeName TResult, TypeName ... targs> struct Partiallambdatyperetriver<tresult (__thiscall tclass::*) (Function<tresult (TArgs ...) ", Targs ...)

  const> {typedef TResult functiontype (Targs ...); typedef TResult LAMBDATYPE (Function<tresult (Targs ...)

  ", Targs ...);

typedef ybuilder<tresult, targs...> Ybuildertype;

 

}; Template<typename tlambda> function<typename Partiallambdatyperetriver<decltype (&TLambda::o Perator ()) >::FunctionType> Y (Tlambda partiallambda) {return typename Partiallambdatyperetriver<decltype (& Amp

Tlambda::operator ()) >::ybuildertype (PARTIALLAMBDA); int _tmain (int argc, _tchar* argv[]) {Auto fib = Y ([] (function<int (int) > self, int index) {retur N index<2 1:self (index-1) +sElf (index-2);

 

  });

  for (int i = 0; i < i++) {cout << fib (i) << "";

} cout << Endl; }