#include <kickstart/all.hpp>        // https://github.com/alf-p-steinbach/kickstart/
using namespace kickstart::all;     // input, to_vector_, split_on_whitespace, out, endl

#include <unordered_map>
using std::unordered_map;

void cppmain()
{
    using Op = function<auto( double, double ) -> double>;
    const unordered_map<string_view, Op> ops =
    {
        { "+", std::plus() }, { "-", std::minus() },
        { "*", std::multiplies() }, { "/", std::divides() }
    };

    const string    op_symbol       = input( "Enter an operator: " );
    const Op        op              = ops.at( op_symbol );

    const string    number_specs    = input( "Enter two numbers: " );
    const auto      numbers         = to_vector_<double>( split_on_whitespace( number_specs ) );

    const auto [a, b] = array{numbers.at( 0 ), numbers.at( 1 )};
    out << a << " " << op_symbol << " " << b << " = " << op( a, b ) << "." << endl;
}

auto main() -> int { return with_exceptions_displayed( cppmain ); }