Declarative configuration predates Nix, there are many far more popular options both before and after Nix, and generally declarative configuration is only ever

Declarative configuration predates Nix, there are many far more popular options both before and after Nix, and generally declarative configuration is only ever popular/used in a few specific domains/niches. I remember being enamored by Haskell in college and I asked my professor why pure functional languages aren't more popular. His answer really stuck with me. He said: because reality is stateful. Reality is stateful. As a consequence, declarative configuration leaks like a sieve, and leaky abstractions suck. When you think about it, declarative configuration is just a DSL for implementing idempotent deployment flow, and idempotent deployment flows in general are quite successful (e.g., Docker, Flatpak, Ansible), and so declarative configuration tends to work okay for restricted subsets of those domains.