refactor(flake-parts): make outputs option more consistent, use mkMerge for merging, default projectRoot to self

examples/_d2n-flake-parts/flake.nix

@@ -1,6 +1,6 @@
 {
   inputs = {
-    dream2nix.url = "github:nix-community/dream2nix";
+    dream2nix.url = "path:../..";
     nixpkgs.follows = "dream2nix/nixpkgs";
     flake-parts.url = "github:hercules-ci/flake-parts";
     src.url = "github:BurntSushi/ripgrep/13.0.0";
@@ -18,8 +18,6 @@
       systems = ["x86_64-linux"];
       imports = [dream2nix.flakeModuleBeta];
 
-      dream2nix.config.projectRoot = ./.;
-
       perSystem = {config, ...}: {
         # define an input for dream2nix to generate outputs for
         dream2nix.inputs."ripgrep" = {

src/modules/flake-parts/implementation.nix

@@ -25,30 +25,24 @@ in {
         inherit (d2n) config;
       };
 
-      outputsRaw =
+      outputs =
         l.mapAttrs
         (_: args: instance.makeOutputs args)
         config.dream2nix.inputs;
 
       getAttrFromOutputs = attrName:
-        d2n.lib.dlib.mergeFlakes (
+        l.mkMerge (
           l.mapAttrsToList
-          (_: attrs: attrs.${attrName})
-          outputsRaw
+          (_: output: mkDefaultRecursive output.${attrName})
+          outputs
         );
     in {
       config = {
-        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");
+        dream2nix = {inherit instance outputs;};
+        # TODO(yusdacra): we could combine all the resolveImpure here if there are multiple
+        # TODO(yusdacra): maybe we could rename outputs with the same name to avoid collisions?
+        packages = getAttrFromOutputs "packages";
+        devShells = getAttrFromOutputs "devShells";
       };
     };
   };

src/modules/flake-parts/interface.nix

@@ -1,4 +1,5 @@
 {
+  self,
   lib,
   flake-parts-lib,
   ...
@@ -20,7 +21,9 @@ in {
         type = t.submoduleWith {
           modules = [../config];
         };
-        default = {};
+        default = {
+          projectRoot = self;
+        };
         description = ''
           The dream2nix config.
         '';
@@ -47,11 +50,10 @@ in {
               '';
             };
             outputs = l.mkOption {
-              type = t.either (t.attrsOf t.raw) (t.attrsOf (t.attrsOf t.raw));
+              type = t.lazyAttrsOf (t.lazyAttrsOf 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.
               '';
             };
           };