Fusion is a programming language designed for implementing reusable components (libraries) for C, C++, C#, D, Java, JavaScript, Python, Swift, TypeScript and OpenCL C, all from single codebase.

A "Hello, world" library:

public class HelloFu
{
    public static string GetMessage()
    {
        return "Hello, world!";
    }
}

can be translated to all the listed languages with:

fut -o hello.c,cpp,cs,d,java,js,py,swift,ts,cl hello.fu

The translated code is lightweight (no virtual machine, emulation nor dependencies), human-readable and fits well with the target language, including naming conventions and documentation comments.

Check out Fusion Playground in your browser.

For further instructions, see Getting Started.