nix-for-dev

A zero-input flake.nix reduces cold eval time by declaring no top-level inputs and pinning nixpkgs with npins. This setup provides fast, deterministic dev shells by isolating the user-facing environment from internal Nix logic.

Separating user-facing devShells from internal Nix logic is achieved by using distinct default.nix and shell.nix files for reproducible environments, while routing non-user-facing scenarios through sub-flakes to maintain clean project boundaries.

npins pinning replaces traditional flake inputs to source nixpkgs deterministically. By keeping the top-level flake.nix free of inputs and sourcing pinned dependencies via npins, you get reproducible builds across platforms without a large inputs graph.

Yes, sub-flakes support non-user-facing configurations by isolating internal Nix logic from the primary user-facing devShell. This layout keeps the top-level flake.nix zero-input while managing language-specific templates and internal workflows separately.

Yes, running the initial setup to pin nixpkgs with npins is required before starting a dev shell with nix develop. This ensures the zero-input Nix environment boots quickly and remains deterministic across different platforms.

Nix flake eval slows down due to a large, all-encompassing inputs graph. You can avoid this by adopting a zero-inputs principle where the top-level flake.nix declares no inputs and sources are pinned with npins for fast iteration.