nix

Nix flakes provide reproducible development environments by declaring dependencies in flake.nix. Create a flake.nix file, define your derivations and inputs, then run `nix flake update` to lock versions in flake.lock, and `nix develop` to enter the environment with all dependencies available.

Derivations are Nix's low-level build specification defining how to fetch, configure, and compile software from source. Packages are higher-level abstractions built from derivations that simplify dependency management and provide pre-configured, reusable software definitions for end users.

Use fetchFromGitHub in your derivation's src attribute to fetch source code directly from GitHub repositories. Specify the owner, repo, rev (commit/tag), and sha256 hash; Nix automatically clones and verifies the source, making it available for the build phases.

Yes. Flakes can define both NixOS system configurations and Home Manager profiles in a single flake.nix. This approach centralizes dependency management, pins versions across system and user environments, and enables reproducible multi-machine setups with shared declarative configuration.

Nix derivations ensure reproducible builds by capturing all dependencies, build inputs, and environment variables in a declarative specification. This eliminates "works on my machine" problems, enables rollbacks, and allows multiple versions of the same package to coexist without conflicts.

Check the derivation's buildInputs and nativeBuildInputs to ensure all required tools are declared. Use `nix-shell` or `nix develop` to inspect the build environment interactively, run `nix flake check` to validate your flake, and consult nixpkgs for correct package names and derivation patterns.