C FFI

Call any C library by declaring external functions.

Declaring extern functions

extern fn puts(s: *u8): i32
extern fn printf(fmt: *u8, ...): i32
extern fn sqrt(x: f64): f64
extern fn malloc(size: u64): *u8

Calling them

Extern function calls require an unsafe block:

fn main(): i32 {
    let root = unsafe { sqrt(2.0) }
    print("sqrt(2) = ", root)
    return 0
}

String coercion

Strings auto-coerce to *u8 when passed to extern functions:

extern fn puts(s: *u8): i32

fn main(): i32 {
    puts("Hello from C!")    // string -> *u8 automatically
    return 0
}

Compile-time file embedding

Inline file contents as a string at compile time:

let html = embedFile("index.html")