nilla-nix/flake-compat

A Nix helper for loading flakes with support for replacing inputs.

{
  "createdAt": "2025-05-13T01:25:35Z",
  "defaultBranch": "main",
  "description": "A Nix helper for loading flakes with support for replacing inputs.",
  "fullName": "nilla-nix/flake-compat",
  "homepage": null,
  "language": "Nix",
  "name": "flake-compat",
  "pushedAt": "2025-05-13T09:03:53Z",
  "stargazersCount": 8,
  "topics": [],
  "updatedAt": "2025-11-16T19:39:51Z",
  "url": "https://github.com/nilla-nix/flake-compat"
}

Flake Compat

Load Nix flakes with support for replacing inputs.

Usage

First, fetch this repository using either a built-in fetcher or a tool like npins.

npins init --bare

npins add github nilla-nix flake-compat

With the library fetched, you can import it and use the compat.load function.

let
    pins = import ./npins;

    compat = import pins.flake-compat;

    flake = compat.load {
        # Specify the directory of the flake you want to load.
        src = ./.;

        # Optionally specify replacements for any inputs.
        replacements = {};
    };
in
    flake

Replacements

A replacement can be specified for any Flake input named in the associated flake.lock file. The value will be substituted directly, so it is necessary to ensure that valid input values are used. This means that if you are replacing an input that is loaded as a flake then your value must also provide things like outputs, sourceInfo, etc.

The compat.fetch and compat.lib.info.from.* helpers simplify this process.

let
    pins = import ./npins;

    compat = import pins.flake-compat;

    flake = compat.load {
        src = ./.;

        replacements = {
            nixpkgs-stable = flake.inputs.nixpkgs-unstable;

            my-archive =
                compat.fetch
                    (compat.lib.info.from.path ./my-archive);
        };
    };
in
    flake