Nix's build graph now rolls dice: dynamic derivations make builds monadic

A build graph that rolls dice

Dynamic derivations turn Nix from an applicative build system—where the entire graph is known up front—into a monadic one where each step can depend on the result of the previous. The author demonstrates with a chain that rolls a die and either stops or continues, showing the graph growing during the build. He argues this primitive goes far beyond lang2nix tools, enabling search, crawling, and emulation with no depth limit.