I'm too dumb for Zig's new IO interface

Summary

I'm too dumb for Zig's new IO interface Aug 22, 2025 You might have heard that Zig 0.15 introduces a new IO interface, with the focus for this release being the new std.Io.Reader and std.Io.Writer types. The old "interfaces" had problems. Like this performance issue that I opened. And it relied on a mix of types, which always confused me, and a lot of anytype - which is generally great, but a poor foundation to build an interface on. I've been slowly upgrading my libraries, and I ran into changes to the tls.Client client used by my smtp library. For the life of me, I just don't understand how it works. Zig has never been known for its documentation, but if we look at the documentation for tls.Client.init, we'll find: pub fn init(input: *std.Io.Reader, output: *std.Io.Writer, options: Options) InitError!Client Initiates a TLS handshake and establishes a TLSv1.2 or TLSv1.3 session. So it takes one of these new Readers and a new Writer, along with some options (sneak peak, which aren't all optional). It doesn't look like you can just give it a net.Stream, but net.Stream does expose a reader() and writer() method, so that's probably a good place to start: const stream = try std.net.tcpConnectToHost(allocator, "www.openmymind.net", 443); defer stream.close(); var writer = stream.writer(&.{}); var reader = stream.reader(&.{}); var tls_client = try std.crypto.tls.Client.init( reader.interface(), &writer.interface, .{}, ); Note that stream.writer() returns a Stream.Writer and stream.reader() returns a Stream.Reader - those aren't the types our tls.Client expects. To convert the Stream.Reader to an *std.Io.Reader, we need to call its interface() method. To get a *std.io.Writer from an Stream.Writer, we need the address of its &interface field. This doesn't seem particularly consistent. Don't forget that the writer and reader need a stable address. Because I'm trying to get the simplest example working, this isn't an issue - everything will live on the stack of main. In a rea...