Nix, The Build-Everything Language (with Julian Arni)

It works on my machine. The phrase is so common it has become a joke, but the problem it describes is real and costly: subtle differences in development environments cause builds to fail on one computer and succeed on another. The standard fix has been Docker, which ships an entire operating system to everyone who needs it. But as Julian Arni explains in this episode of Developer Voices, Docker solves one problem while creating others—and an older, more principled alternative called Nix offers a different path.

Nix began as a PhD thesis on making builds reliable and has grown into a tool that can define and build nearly any programming environment. The core idea is simple: take the package lock file concept that languages like Rust (Cargo) and JavaScript (npm) already use, and extend it to everything—not just language dependencies, but system libraries, compilers, kernel versions, and even the UTC time. Every input to a build is pinned by its cryptographic hash. Build the same project twice, and you get byte-for-byte the same output.