XIEITE_FN(), XIEITE_FN_LOCAL()

 Defined in header <xieite/fn.hpp>
(header-only: <xieite/pp/fn.hpp>)

Allows a shorthand lambda syntax:
 XIEITE_FN($0 + $1)
which is equivalent to writing:
 [](auto&& a, auto&& b) noexcept(noexcept(a + b)) -> decltype(a + b) { return a + b; }

The body of a shorthand lambda has access to a parameter pack $$ containing all arguments, a template parameter pack $$_ containing all template arguments, variables $0 through $256 which correspond to individual arguments passed to the lambda, and types $0_ through $256_ which correspond to individual template arguments.
Accessing a variable or type which does not correspond to an argument (when the number of arguments is not greater than a variable's index or the number of template arguments is not greater than a type's index) results in some unusable value.


Definitions

 #0 
#define XIEITE_FN(...) /* ... */
Expands to a lambda with no capture-default.

#1 
#define XIEITE_FN_LOCAL(...) /* ... */
Expands to a lambda with a reference capture-default.


Example

 
#include <xieite/fn.hpp>

import xieite;

int main() {
	auto add_two = XIEITE_FN($0 + $1);
	auto add_all = XIEITE_FN(... + $$);
	auto cast = XIEITE_FN(static_cast<$0_>($0));

	xieite::dump(add_two(1, 2));
	xieite::dump(add_all(1, 2, 3, 4, 5));
	xieite::dump(cast.operator()<int>(6.28318));
}
Output: 
3
15
6