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")

The @ marks a compiler-level construct, like @cLayout and @link above — the argument must be a string literal and the path resolves relative to the file containing the call. Contents are read as raw bytes, so binary assets embed intact. The bare embedFile("index.html") still compiles but warns (bare-embedfile).