prod

prod_t kumi::prod {}

inlineconstexprnodiscard

Callable object computing the product of all elements.

On record types, this function operates on the underlying values, not on the fields themselves.

Note

For associative operations, this produces the same result as a left or right fold, but have different intermediate evaluation order.

inline constexpr

Header file

#include <kumi/algorithm/reduce.hpp>

Call Signature

template<product_type T>
constexpr auto prod(T && t);

template<product_type T, typename V>
constexpr auto prod(T && t, V init);

Parameters

• t: Product Type to operate on
• init: Optional initial value of the reduction.

Return value

The result of the computation of `get<0>(t) * ... * get<N-1>(t) * init`

Helper type

namespace kumi::result
{
  template<product_type T, typename Value> struct prod;
 
  template<product_type T, typename Value>
  using prod_t = typename prod<T,Value>::type;
}

Computes the return type of a call to kumi::prod

Examples

Tuple

#include <kumi/kumi.hpp>
#include <iostream>
 
int main()
{
  auto t = kumi::tuple{2.,5,short{3},'\4'};
 
  std::cout << kumi::prod(t, 10) << "\n";
  std::cout << kumi::prod(t) << "\n";
}

Record

#include <kumi/kumi.hpp>
#include <iostream>
 
int main()
{
  using namespace kumi::literals;
  auto r = kumi::record{"a"_id = 2.,"b"_id = 5,"c"_id = short{3},"d"_id = '\4'};
 
  std::cout << kumi::prod(r, 10) << "\n";
  std::cout << kumi::prod(r) << "\n";
}