It’s very rare that a technology changes how we build software. Containers allowed us to bundle up a developer environment and isolate it from the host system. Nix allowed us to be rigorous about our dependency tree and build software reproducibly. The next generation of developer environments will pick up where Nix leaves off and make it accessible. Taking things even further, the next generation of developer environments will be *composable* so that your developer environment can context switch and keep up with you as *you* context switch. In this talk I’ll show you that, with Flox, the tooling for this next generation of developer environments already exists.