Foreign Function Interface

The extern keyword declares functions that are defined outside Rux — typically in C / C++ libraries.

extern func malloc(size: uint) -> *opaque;
extern func free(ptr: *opaque);

Import Attribute

The @[Import] attribute links an extern declaration to a specific dynamic library (.dll, .so, .dylib). The operating system loader resolves the library by name at runtime.

@[Import(lib: "libm.so")]
extern func cos(angle: float64) -> float64;

@[Import(lib: "libm.so")]
extern func sin(angle: float64) -> float64;

@[Import(lib: "libm.so")]
extern func sqrt(value: float64) -> float64;

Multiple declarations from the same library can be grouped in one extern block.

@[Import(lib: "Kernel32.dll")]
extern {
    func CreateFileW(
        fileName: *const char16,
        desiredAccess: uint32,
        shareMode: uint32,
        securityAttributes: *SecurityAttributes,
        creationDisposition: uint32,
        flagsAndAttributes: uint32,
        templateFile: *opaque
    ) -> *opaque;

    func WriteFile(
        handle: *opaque,
        buffer: *const opaque,
        numberOfBytesToWrite: uint32,
        numberOfBytesWritten: *uint32,
        overlapped: *Overlapped,
    ) -> bool32;
}

See @[Import] for full attribute reference.