pas a list from R to C++

// [[Rcpp::export]]
Rcpp::List DEoptim_impl(const arma::colvec & minbound,                  // user-defined lower bounds
                        const arma::colvec & maxbound,                  // user-defined upper bounds
                        SEXP fnS,                                       // function to be optimized, either R or C++
                        const Rcpp::List & control,                     // parameters
                        SEXP rhoS) {                                    // optional environment

    double VTR           = Rcpp::as<double>(control["VTR"]);            // value to reach
    int i_strategy       = Rcpp::as<int>(control["strategy"]);          // chooses DE-strategy
    int i_itermax        = Rcpp::as<int>(control["itermax"]);           // Maximum number of generations
    long l_nfeval        = 0;                                           // nb of function evals (NOT passed in)
    int i_D              = Rcpp::as<int>(control["npar"]);              // Dimension of parameter vector
    int i_NP             = Rcpp::as<int>(control["NP"]);                // Number of population members
    int i_storepopfrom   = Rcpp::as<int>(control["storepopfrom"]) - 1;  // When to start storing populations
    int i_storepopfreq   = Rcpp::as<int>(control["storepopfreq"]);      // How often to store populations
    int i_specinitialpop = Rcpp::as<int>(control["specinitialpop"]);    // User-defined inital population
    double f_weight      = Rcpp::as<double>(control["F"]);              // stepsize
    double f_cross       = Rcpp::as<double>(control["CR"]);             // crossover probability
    int i_bs_flag        = Rcpp::as<int>(control["bs"]);                // Best of parent and child
    int i_trace          = Rcpp::as<int>(control["trace"]);             // Print progress?
    int i_check_winner   = Rcpp::as<int>(control["checkWinner"]);       // Re-evaluate best parameter vector?
    int i_av_winner      = Rcpp::as<int>(control["avWinner"]);          // Average
    double i_pPct        = Rcpp::as<double>(control["p"]);              // p to define the top 100p% best solutions