API Development ​

Jule aims to be interoperable with C/C++. But this must go both ways in some cases. So, while you can use C++ codes with Jule, in some cases you may need to use your Jule codes in the C++ backend.

Jule provides the export directive to achieve this. Jule does not provide a standard for how to pass any definitions to the backend. In other words, it is often not possible to know which identifier your Jule codes will be reflected in the backend. To make this consistent and expose your Jule codes to the backend you need to use the export directive.

Jule makes the export directive available only for global variables and functions. It always takes an absolute parameter. This parameter is the identifier that will be used to export.

Here's an example to develop API for your Jule code for the backend:

cpp use "magicheader.hpp"

cpp fn printMagic()

#export "magic_calculation"
fn magicCalculation(x: int, y: int): int {
	ret ((x * y) ^ 1) / 3
}

fn main() {
	cpp.printMagic()
}

The magicheader.hpp:

#ifndef MAGICHEADER_HPP
#define MAGICHEADER_HPP

#include <iostream>
#include "api/jule.hpp"

jule::Int magic_calculation(jule::Int, jule::Int);

void printMagic() {
	jule::Int x = 42;
	jule::Int y = 89;
	std::cout << magic_calculation(x, y) << std::endl;
}

#endif

In the code example above, the Jule function with identifier magicCalculation is passed to the backend with identifier magic_calculation. It is called by a function in the backend with C++ interoperability. In this way, a bidirectional use can be achieved.