refactor(flake-parts): use perSystem for defining inputs, drop makeFlakeOutputs usage

examples/_d2n-flake-parts/flake.nix

@@ -17,10 +17,12 @@
     flake-parts.lib.mkFlake {inherit self;} {
       systems = ["x86_64-linux"];
       imports = [dream2nix.flakeModuleBeta];
-      dream2nix = {
-        config.projectRoot = ./.;
+
+      dream2nix.config.projectRoot = ./.;
+
+      perSystem = {config, ...}: {
         # define an input for dream2nix to generate outputs for
-        inputs."ripgrep" = {
+        dream2nix.inputs."ripgrep" = {
           source = src;
           settings = [{builder = "crane";}];
         };

src/modules/flake-parts/implementation.nix

@@ -5,44 +5,50 @@
 }: let
   l = lib // builtins;
   d2n = config.dream2nix;
-  makeArgs = p:
-    {
-      inherit (config) systems;
-      inherit (d2n) config;
-    }
-    // p;
-  outputs = d2n.lib.dlib.mergeFlakes (
-    l.map
-    (p: d2n.lib.makeFlakeOutputs (makeArgs p))
-    (l.attrValues d2n.inputs)
-  );
+
+  # make attrs default, so that users can override them without
+  # needing to use lib.mkOverride (usually, lib.mkForce)
+  mkDefaultRecursive = attrs:
+    l.mapAttrsRecursiveCond
+    d2n.lib.dlib.isNotDrvAttrs
+    (_: l.mkDefault)
+    attrs;
 in {
   config = {
-    flake =
-      # make attrs default, so that users can override them without
-      # needing to use lib.mkOverride (usually, lib.mkForce)
-      l.mapAttrsRecursiveCond
-      d2n.lib.dlib.isNotDrvAttrs
-      (_: l.mkDefault)
-      outputs;
-    dream2nix.outputs = outputs;
     perSystem = {
       config,
-      system,
+      pkgs,
       ...
     }: let
-      # get output attrs that have systems
-      systemizedOutputs =
+      instance = d2n.lib.init {
+        inherit pkgs;
+        inherit (d2n) config;
+      };
+
+      outputsRaw =
         l.mapAttrs
-        (_: attrs: attrs.${system})
-        (
-          l.filterAttrs
-          (_: attrs: l.isAttrs attrs && l.hasAttr system attrs)
-          outputs
+        (_: args: instance.makeOutputs args)
+        config.dream2nix.inputs;
+
+      getAttrFromOutputs = attrName:
+        d2n.lib.dlib.mergeFlakes (
+          l.mapAttrsToList
+          (_: attrs: attrs.${attrName})
+          outputsRaw
         );
     in {
       config = {
-        dream2nix.outputs = systemizedOutputs;
+        dream2nix = {
+          inherit instance;
+          outputs =
+            # if only one input was defined, then only export outputs from
+            # that since there is nothing else
+            if l.length (l.attrNames outputsRaw) != 1
+            then outputsRaw
+            else l.head (l.attrValues outputsRaw);
+        };
+        devShells = mkDefaultRecursive (getAttrFromOutputs "devShells");
+        packages = mkDefaultRecursive (getAttrFromOutputs "packages");
       };
     };
   };

src/modules/flake-parts/interface.nix

@@ -22,28 +22,7 @@ in {
         };
         default = {};
         description = ''
-          The dream2nix config. This will be applied to all defined `sources`.
-          You can override this per `source` by specifying `config` for that source:
-          ```nix
-            sources."name" = {
-              config.projectSource = ./source;
-            };
-          ```
-        '';
-      };
-      inputs = l.mkOption {
-        type = t.attrsOf t.attrs;
-        default = {};
-        description = ''
-          A list of inputs to generate outputs from.
-          Each one takes the same arguments `makeFlakeOutputs` takes.
-        '';
-      };
-      outputs = l.mkOption {
-        type = t.attrsOf t.raw;
-        readOnly = true;
-        description = ''
-          The raw outputs that were generated.
+          The dream2nix config.
         '';
       };
     };
@@ -52,11 +31,27 @@ in {
       ({...}: {
         options = {
           dream2nix = {
-            outputs = l.mkOption {
-              type = t.attrsOf t.raw;
+            instance = l.mkOption {
+              type = t.raw;
               readOnly = true;
               description = ''
-                The raw outputs that were generated.
+                The dream2nix instance.
+              '';
+            };
+            inputs = l.mkOption {
+              type = t.attrsOf t.attrs;
+              default = {};
+              description = ''
+                A list of inputs to generate outputs from.
+                Each one takes the same arguments `makeOutputs` takes.
+              '';
+            };
+            outputs = l.mkOption {
+              type = t.either (t.attrsOf t.raw) (t.attrsOf (t.attrsOf t.raw));
+              readOnly = true;
+              description = ''
+                The raw outputs that were generated for each input.
+                If only one input was specified, then this will be the outputs for only that input.
               '';
             };
           };