map()

template<concepts::product_type T, typename Function, concepts::sized_product_type< size_v< T > >... Ts>
requires (concepts::compatible_product_types<T, Ts...>)

auto kumi::map ( Function f, T && t0, Ts &&... others )

inlinenodiscardconstexpr

Applies the Callable object f on each product types' elements.

Applies the given function to all the product types passed as arguments and stores the result in another product type, keeping the original elements order. On records, the order is determined via the order of definition of the fields.

Note

Does not participate in overload resolution if product types' size are not equal or if f can't be called on each product type's elements. All product type must either be record types or product types, mixing is not supported.

Parameters

f	Callable function to apply
t0	Product Type to operate on
others	Product Types to operate on

Returns

The product type of f calls results.

Helper type

namespace kumi::result
{
  template<typename Function, product_type T, product_type... Ts> struct map;
 
  template<typename Function, product_type T, product_type... Ts>
  using map_t = typename map<Function,T>::type;
}

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

Examples:

Tuple:

#include <kumi/kumi.hpp>
#include <iostream>
 
int main()
{
  auto lhs = kumi::tuple{1,2,3};
  auto rhs = kumi::tuple{2.5,3.6,4.7};
 
  auto res = kumi::map( [](auto l, auto r) { return l*r; }, lhs, rhs);
 
  std::cout << res << "\n";
}

Record:

#include <kumi/kumi.hpp>
#include <iostream>
 
int main()
{
  using namespace kumi::literals;
  auto lhs = kumi::record{"a"_id = 1,"b"_id = 2,"c"_id = 3};
  auto rhs = kumi::record{"a"_id = 2.5,"b"_id = 3.6,"c"_id = 4.7};
 
  auto res = kumi::map( [](auto l, auto r) { return l*r; }, lhs, rhs);
 
  std::cout << res << "\n";
}