Individual Features

README.md

@@ -1,2 +1,57 @@
+[![project chat](https://img.shields.io/badge/zulip-join_chat-brightgreen.svg)](https://nixos.zulipchat.com/#narrow/stream/413950-nix)
+
 # just-flake
-Convenient way to use [`just`](https://just.systems/) in your Nix devShells
+
+Use [`just`](https://just.systems/) in your Nix devShells with re-usable and share-able targets.
+
+> [!WARNING] 
+> Module options API is subject to change.
+
+
+## Usage
+
+In your `flake.nix`:
+
+```nix
+# In flake-parts' perSystem
+{
+  just-flake.features = {
+    treefmt.enable = true;
+    rust.enable = true;
+    convco.enable = true;
+    hello = {
+      enable = true;
+      justfile = ''
+        hello:
+        echo Hello World
+      '';
+      };
+  };
+}
+```
+
+In your `justfile`:
+
+```just
+# See flake.nix (just-flake)
+import 'just-flake.just'
+
+# Display the list of recipes
+default:
+    @just --list
+```
+
+Then, add `config.just-flake.outputs.devShell` to the `inputsFrom` of your devShell.
+
+Resulting devShell banner:
+
+```
+🍎🍎 Run 'just <recipe>' to get started
+Available recipes:
+    changelog # Generate CHANGELOG.md using recent commits
+    default   # Display the list of recipes
+    fmt       # Auto-format the source tree using treefmt
+    hello
+    test      # Run and watch 'cargo test'
+    w         # Compile and watch the project
+```

flake-module.nix

@@ -1,12 +1,64 @@
 {
-  perSystem = { pkgs, ... }: {
-    devShells.just = pkgs.mkShell {
-      packages = [ pkgs.just ];
-      shellHook = ''
-        echo
-        echo "🍎🍎 Run 'just <recipe>' to get started"
-        just
-      '';
-    };
+  perSystem = { config, pkgs, lib, ... }: {
+    options =
+      let
+        inherit (lib) types;
+      in
+      {
+        just-flake = lib.mkOption {
+          default = { };
+          type = types.submoduleWith {
+            specialArgs = { inherit pkgs; };
+            modules = [{
+              imports = [
+                ./nix/features.nix
+              ];
+
+              options = {
+                commonFileName = lib.mkOption {
+                  type = lib.types.str;
+                  default = "just-flake.just";
+                  description = ''
+                    The name of the common justfile generated by this module.
+                  '';
+                };
+
+                outputs.devShell = lib.mkOption {
+                  type = lib.types.package;
+                  readOnly = true;
+                  description = ''
+                    The output devShell to include in `inputsFrom`.
+                  '';
+                };
+              };
+            }];
+          };
+        };
+      };
+    config =
+      let
+        cfg = config.just-flake;
+      in
+      {
+        just-flake.outputs.devShell =
+          let
+            commonJustfile = pkgs.writeTextFile {
+              name = "justfile";
+              text =
+                lib.concatStringsSep "\n"
+                  (lib.mapAttrsToList (name: feature: feature.outputs.justfile) cfg.features);
+            };
+          in
+          pkgs.mkShell {
+            packages = [ pkgs.just ];
+            shellHook = ''
+              ln -sf ${builtins.toString commonJustfile} ./${cfg.commonFileName}
+
+              echo
+              echo "🍎🍎 Run 'just <recipe>' to get started"
+              just --list
+            '';
+          };
+      };
   };
 }

nix/feature.nix

@@ -0,0 +1,32 @@
+{ config, name, lib, pkgs, ... }:
+
+{
+  options = {
+    enable = lib.mkEnableOption "Enable this feature";
+    justfile = lib.mkOption {
+      type = lib.types.either lib.types.str lib.types.path;
+      description = ''
+        The justfile representing this feature.
+      '';
+      apply = x:
+        if builtins.isPath x then x else
+        pkgs.writeTextFile {
+          name = "${name}.just";
+          text = x;
+        };
+    };
+    outputs.justfile = lib.mkOption {
+      type = lib.types.str;
+      readOnly = true;
+      description = ''
+        The justfile code for importing this feature's justfile.
+
+        See https://just.systems/man/en/chapter_53.html
+      '';
+      default =
+        if config.enable
+        then "import '${builtins.toString config.justfile}'"
+        else "";
+    };
+  };
+}

nix/features.nix

@@ -0,0 +1,61 @@
+# This largely inspired by the use of freeformType in 
+# https://github.com/cachix/git-hooks.nix/blob/master/modules/hooks.nix
+{ pkgs, lib, ... }:
+
+let
+  inherit (lib) types;
+  featureMod = {
+    imports = [ ./feature.nix ];
+    config._module.args = { inherit pkgs; };
+  };
+  featureType = types.submodule featureMod;
+in
+{
+  imports = [{
+    options.features = lib.mkOption {
+      type = types.submoduleWith {
+        modules = [{ freeformType = types.attrsOf featureType; }];
+        specialArgs = { inherit pkgs; };
+      };
+      default = { };
+    };
+  }];
+
+  # NOTE: At somepoint, we may want to add `settings` options to some of these features.
+  options.features = {
+    convco = lib.mkOption {
+      description = "Add the 'changelog' target calling convco";
+      type = types.submodule { imports = [ featureMod ]; };
+    };
+    rust = lib.mkOption {
+      description = "Add 'w' and 'test' targets for running cargo";
+      type = types.submodule { imports = [ featureMod ]; };
+    };
+    treefmt = lib.mkOption {
+      description = "Add the 'fmt' target to format source tree using treefmt";
+      type = types.submodule { imports = [ featureMod ]; };
+    };
+  };
+
+  config.features = lib.mapAttrs (_: lib.mapAttrs (_: lib.mkDefault)) {
+    convco.justfile = ''
+      # Generate CHANGELOG.md using recent commits
+      changelog:
+        convco changelog -p ""
+    '';
+    rust.justfile = ''
+      # Compile and watch the project
+      w:
+        cargo watch
+
+      # Run and watch 'cargo test'
+      test:
+        cargo watch -s "cargo test"
+    '';
+    treefmt.justfile = ''
+      # Auto-format the source tree using treefmt
+      fmt:
+        treefmt
+    '';
+  };
+}