How Nix Actually Works

Most people meet Nix as a package manager, get scared by the syntax, and leave. That's a shame, because the whole thing is built on about three ideas. Once they click, the weird /nix/store/ paths, the reproducibility, the rollbacks, all of it stops being magic. No fluff. Let's look at what Nix is actually doing under the hood. 1. The language is just a calculator for attribute sets Before any packaging, Nix is a small, lazy, purely functional language. No statements, no loops, no mutation. Every expression evaluates to a value. Open a repl and poke it: $ nix repl nix-repl> 1 + 2 3 nix-repl> "pwn" + "writer" "pwnwriter" nix-repl> { name = "nix"; year = 2003; } { name = "nix"; year = 2003; } nix-repl> let x = 10; in x * x 100 Functions are arg: body. That colon is the whole syntax. nix-repl> square = x: x * x nix-repl> square 12 144 nix-repl> greet = name: "hello ${name}" nix-repl> greet "world" "hello world" Everything you write in Nix is one big expression that evaluates to an…