prod() [2/2]

template<concepts::product_type T, typename Value>

auto kumi::prod ( T && t, Value init )

inlinenodiscardconstexpr

Computes the product of all elements.

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

Parameters

t	Product type to operate on
init	Initial value of the product

Returns

The value 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";
}