top-level refactor (#17)

* top-level refactor For very simple flakes, it doesn't make sense to create a whole folder structure. ADDITIONS: * Add a top-level package.nix that maps to `packages.<system>.default` * Add a top-level formatter.nix that maps to `formatter.<system>` and `packages.<system>.formatter`. * Load devshells from the devshells/ folder. CHANGES: * perSystem values now merge legacyPackages and packages in that order. * packages are loaded with `callPackage`. BREAKING: * Remove `packages/<pname>/package.nix` as it makes the interface too complicated. * lib/default.nix: take `{ flake, inputs }:` instead of `inputs`. * README: remove old packages folder section This is now covered in the main docs
numtide · Jun 26, 2024 · 8fb69fb · 8fb69fb
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diff --git a/README.md b/README.md
@@ -4,7 +4,7 @@
 
 ## What's blueprint?
 
-Blueprint is a light framework that replaces Nix glue code with a regular folder structure. Focus on deploying your infrastructure / package sets instead of reinventing the wheel.
+Blueprint replaces Nix glue code with a regular folder structure. Focus on deploying your infrastructure / package sets instead of reinventing the wheel.
 
 The ambition is to handle all the workflows to reduce the cost of self-hosting infrastructure (we're not quite there yet).
 
@@ -27,18 +27,20 @@ In some ways, this is the spiritual successor to `flake-utils`, my first
 attempt at making flakes easier to use.
 
 What it's good for:
+
 * Home and SME configurations
 * Package sets
 
 What it's bad for:
+
 * Complicated setups (although we try to provide gracefull fallback)
 * Developer environments (see devenv.sh)
 
 ## Design principles
 
+* User workflows come first.
 * KISS. We don't need complicated module systems with infinite recursions.
 * 1:1 mapping. Keep the mapping between attributes predictable.
-* Think about user workflows.
 
 ## Features
 
@@ -54,24 +56,6 @@ What it's bad for:
 * Darwin configurations
 * devshell
 
-## Blacklisted inputs
-
-In order to avoid name clashes, avoid loading inputs with the following names:
-* lib
-* pname
-* system
-* pkgs
-
-## Packages folder
-
-If the ./pkgs folder exists, load every sub-folder in it and map it to the `packages` output.
-
-Each sub-folder should contain a `default.nix`, with the following function
-signature:
-
-* pname: name of the folder. Useful to inject back.
-* all the inputs
-
 ## How to support overrides?
 
 Don't
@@ -80,12 +64,9 @@ Don't
 
 Don't
 
-
 ## Related projects
 
 * [flake-utils](https://github.com/numtide/flake-utils) the OG for flake libraries.
-* [flake-utils-plus]() extending flake-utils with more stuff.
 * [flake-parts](https://flake.parts) uses the Nix module system. It's too complicated for my taste.
-* [std]() ??
-* [snowflake-lib](TODO)
-
+* [std](https://github.com/divnix/std)
+* [snowflake-lib](https://github.com/snowfallorg/lib)
diff --git a/docs/folder-structure.md b/docs/folder-structure.md
@@ -2,13 +2,17 @@
 
 ## High-level
 
-* `devshell.nix` for your developer shell.
+* `devshells/` for devshells.
 * `hosts/` for machine configurations.
 * `lib/` for Nix functions.
 * `modules/` for NixOS and other modules.
-* `pkgs/` for packages. 
+* `packages/` for packages.
 * `templates/` for flake templates.
 
+* `devshell.nix` for the default devshell
+* `formatter.nix` for the default formatter
+* `package.nix` for the default package
+
 ## File arguments
 
 Each file typically gets passed a number of arguments.
@@ -20,23 +24,26 @@ Some of the files are instantiated multiple times, once per configured system. S
 Those take the following arguments:
 
 * `inputs`: maps to the flake inputs.
+* `flake`: maps to the flake itself. It's a shorthand for `inputs.self`.
 * `system`: the current system attribute.
 * `perSystem`: contains the packages of all the inputs, filtered per system.
     Eg: `perSystem.nixos-anywhere.default` is a shorthand for `inputs.nixos-anywhere.packages.<system>.default`.
-* `flake`: points to the current flake. It's a shorthand for `inputs.self`.
 * `pkgs`: and instance of nixpkgs, see [configuration](configuration.md) on how it's configured.
 
 ## Mapping
 
-### `devshell.nix`
+### `devshell.nix`, `devshells/<pname>(.nix|/default.nix)`
 
 Contains the developer shell if specified.
 
-Called with the [per-system](#per-system) attributes.
+Inputs:
+
+The [per-system](#per-system) values, plus the `pname` attribute.
 
 Flake outputs:
-* `devShells.<system>.default`
-* `checks.<system>.devshell`
+
+* `devShells.<system>.<pname>`
+* `checks.<system>.devshell-<pname>`
 
 #### Example
 
@@ -50,7 +57,7 @@ pkgs.mkShell {
 }
 ```
 
-### `hosts/<hostname>/(configuration.nix|darwin-configuration.nix)` 
+### `hosts/<hostname>/(configuration.nix|darwin-configuration.nix)`
 
 Each folder contains either a NixOS or nix-darwin configuration:
 
@@ -59,10 +66,12 @@ Each folder contains either a NixOS or nix-darwin configuration:
 Evaluates to a NixOS configuration.
 
 Additional values passed:
+
 * `inputs` maps to the current flake inputs.
 * `flake` maps to `inputs.self`.
 
 Flake outputs:
+
 * `nixosConfigurations.<hostname>`
 * `checks.<system>.nixos-<hostname>` - contains the system closure.
 
@@ -87,35 +96,43 @@ Flake outputs:
 Evaluates to a [nix-darwin](https://github.com/LnL7/nix-darwin) configuration.
 
 To support it, also add the following lines to the `flake.nix` file:
+
 ```nix
 {
   inputs.nix-darwin.url = "github:LnL7/nix-darwin";
 }
 ```
 
 Additional values passed:
+
 * `inputs` maps to the current flake inputs.
 * `flake` maps to `inputs.self`.
 
 Flake outputs:
+
 * `darwinConfiguration.<hostname>`
 * `checks.<system>.darwin-<hostname>` - contains the system closure.
 
 ### `lib/default.nix`
 
 Loaded if it exists.
 
-It takes the `inputs` as a positional argument.
+Inputs:
+
+* `flake`
+* `inputs`
+
+Flake outputs:
+
+* `lib` - contains the return value of `lib/default.nix`
 
 Eg:
+
 ```nix
-inputs:
+{ flake, inputs }:
 { }
 ```
 
-Flake outputs:
-* `lib` - contains the return value of `lib/default.nix`
-
 ### `modules/<type>/(<name>|<name>.nix)`
 
 Where the type can be:
@@ -125,24 +142,28 @@ Where the type can be:
 
 These and other unrecognized types also make to `modules.<type>.<name>`.
 
-### `packages/<pname>/(default.nix|package.nix)`
+### `package.nix`, `formatter.nix`, `packages/<pname>(.nix|/default.nix)`
+
+This `packages/` folder contains all your packages.
 
-This folder contains all your packages.
+For single-package repositories, we also allow a top-level `package.nix` that
+maps to the "default" package.
+
+Inputs:
+
+The [per-system](#per-system) values, plus the `pname` attribute.
 
 Flake outputs:
+
 * `packages.<system>.<pname>` - will contain the package
 * `checks.<system>.pkgs-<pname>` - also contains the package for `nix flake check`.
 * `checks.<system>.pkgs-<pname>-<tname>` - adds all the package `passthru.tests`
 
-#### `default.nix`
+#### `default.nix` or top-level `package.nix`
 
 Takes the "per-system" arguments. On top of this, it also takes a `pname`
 argument.
 
-#### `package.nix`
-
-Use this when copying packages from `nixpkgs/pkgs/by-name`. `pkgs.callPackage` is called onto it.
-
 #### `templates/<name>/`
 
 Use this if you want your project to be initializable using `nix flake init`.
@@ -152,4 +173,5 @@ This is what is used by blueprint in the [getting started](getting-started.md) s
 If no name is passed, it will look for the "default" folder.
 
 Flake outputs:
-* `templates.<name>`
+
+* `templates.<name> -> path`
diff --git a/flake.nix b/flake.nix
@@ -9,8 +9,8 @@
   outputs =
     inputs:
     let
-      # use self to create self
-      blueprint = import ./lib inputs;
+      # Use self to create self
+      blueprint = import ./lib { inherit inputs; };
     in
     blueprint { inherit inputs; };
 }
diff --git a/formatter.nix b/formatter.nix
@@ -0,0 +1,65 @@
+{
+  pname,
+  pkgs,
+  flake,
+}:
+let
+  formatter = pkgs.writeShellApplication {
+    name = pname;
+
+    runtimeInputs = [
+      pkgs.deadnix
+      pkgs.nixfmt-rfc-style
+    ];
+
+    text = ''
+      set -euo pipefail
+      set -x
+
+      deadnix --no-lambda-pattern-names --edit "$@"
+
+      nixfmt "$@"
+    '';
+
+    meta = {
+      description = "format your project";
+    };
+  };
+
+  check =
+    pkgs.runCommand "format-check"
+      {
+        nativeBuildInputs = [
+          formatter
+          pkgs.git
+        ];
+
+        # only check on Linux
+        meta.platforms = pkgs.lib.platforms.linux;
+      }
+      ''
+        export HOME=$NIX_BUILD_TOP/home
+
+        # keep timestamps so that treefmt is able to detect mtime changes
+        cp --no-preserve=mode --preserve=timestamps -r ${flake} source
+        cd source
+        git init --quiet
+        git add .
+        shopt -s globstar
+        ${pname} **/*.nix
+        if ! git diff --exit-code; then
+          echo "-------------------------------"
+          echo "aborting due to above changes ^"
+          exit 1
+        fi
+        touch $out
+      '';
+in
+formatter
+// {
+  passthru = formatter.passthru // {
+    tests = {
+      check = check;
+    };
+  };
+}