Context-aware Dendritic Nix

Context-driven, aspect-oriented, cross-class Nix configurations

Den Framework Den Library Why Den? Source Code

Two Core Principles

Den builds on flake-aspects’ parametric aspects, and provides a declarative context-pipeline as cutting-points for these aspects.

Context Transformation

Data flows through a declarative pipeline of contexts. Each stage enriches the context — from host definitions through user enumeration to domain-specific requirements.

Context-Aware Aspects

Aspects are composable bundles of cross-class Nix configs. They inspect context to produce conditional, parametric configurations — and are activated by a matching context.

1. Context Transformation

Data flows through a declarative pipeline. You declare the entities (data) that exists in your universe, Den transforms them into progressively richer contexts to which aspects are attached, providing configuration for each context:

graph LR
  H["den.ctx.host {host}"] --> U["den.ctx.user {host, user} (for each user)"]
  U --> HM["aspect provides homeManager/hjeim class"]
  H --> OS["aspect provides nixos/darwin class"]

Each stage of the pipeline is a context type defined in den.ctx. Context types declare how to find aspects, how to transform into other contexts, and which parametric includes to activate.

2. Context-Aware Aspects

Aspects are composable bundles that inspect their context parameters to decide what to produce. A function taking { host, ... } only runs when a host context exists. A function taking { host, user, ... } runs once per user on each host.

Functions that require parameters not present in the current context are not included. Den introduces pattern matching on context shape.

Den as a Library

All parts of Den are optional, re-usable and replaceable. Even the default NixOS configuration pipeline is opt-in, and you can use Den lib to configure anything supporting Nix modules.

Any Nix Class

NixOS, Darwin, Home-Manager, Terraform, NixVim — Den works with anything configurable through Nix.

Context Pipeline

Define custom context types with den.ctx. Declarative transformations propagate data through your config graph.

No Lock-in

Works with flakes, without flakes, with flake-parts, or standalone. Den plays well with your existing Nix choices. And integrates with your existing infra.

Sharable Aspects

Re-usablity is one of the goals of Den. Allowing people to create truly-generic configuration modules. Namespaces let you publish and consume aspect libraries across repositories and flakes.

Den as a Framework

Built upon den.lib, Den provides ready-made facilities for the common use-case of OS and User configurations.

Declare Systems

One-liner host and user definitions with freeform schemas. NixOS, Darwin, Home-Manager — all from a single source.

Bidirectional

Hosts configure their users. Users contribute to their hosts. Aspects flow in both directions automatically.

Batteries Included

Opt-in aspects for common tasks: define-user, primary-user, user-shell, unfree packages, import-tree, and more.

Community

Share configurations through namespaces. Real-world setups and a growing ecosystem at denful (wip).

Feel free to to explore the codebase, particularly our included batteries and tests that serve as examples.

Join our community discussion.

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