Can be even simpler now (you can declare it as a local function in a method, so this works when copied to Program.cs as is): var text = "Hello, World!"u8;

Can be even simpler now (you can declare it as a local function in a method, so this works when copied to Program.cs as is): var text = "Hello, World!"u8; write(1, text, text.Length); [DllImport("libc")] static extern nint write(nint fd, ReadOnlySpan<byte> buf, nint count); (note: it's recommended to use [LibraryImport] instead for p/invoke declarations that require marshalling as it does not require JIT/runtime marshalling but just generates (better) p/invoke stub at build time)