flake.nix: refactor, greatly improve

Author: faukah

flake.nix

@@ -2,50 +2,42 @@
   description = "Compositor for the COSMIC desktop environment";
 
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    # <https://github.com/nix-systems/default-linux>
+    systems.url = "github:nix-systems/default-linux";
 
-    parts.url = "github:hercules-ci/flake-parts";
-    parts.inputs.nixpkgs-lib.follows = "nixpkgs";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
 
     crane.url = "github:ipetkov/crane";
 
-    rust.url = "github:oxalica/rust-overlay";
-    rust.inputs.nixpkgs.follows = "nixpkgs";
-
-    nix-filter.url = "github:numtide/nix-filter";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+    rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
   };
 
   outputs = inputs @ {
     self,
-    nixpkgs,
-    parts,
     crane,
-    rust,
-    nix-filter,
     ...
-  }:
-    parts.lib.mkFlake {inherit inputs;} {
-      systems = [
-        "aarch64-linux"
-        "x86_64-linux"
-      ];
-
-      perSystem = {
-        self',
-        lib,
-        system,
-        ...
-      }: let
-        pkgs = nixpkgs.legacyPackages.${system}.extend rust.overlays.default;
-        rust-toolchain = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
-        craneLib = (crane.mkLib pkgs).overrideToolchain rust-toolchain;
+  }: let
+    inherit (inputs.nixpkgs) lib;
+
+    fs = lib.fileset;
+    eachSystem = lib.genAttrs (import inputs.systems);
+    pkgsFor = eachSystem (system:
+      import inputs.nixpkgs {
+        localSystem.system = system;
+        overlays = [(import inputs.rust-overlay)];
+      });
+  in {
+    packages =
+      lib.mapAttrs (system: pkgs: let
+        craneLib = crane.mkLib pkgs;
         craneArgs = {
           pname = "cosmic-comp";
           version = self.rev or "dirty";
 
-          src = nix-filter.lib.filter {
+          src = fs.toSource {
             root = ./.;
-            include = [
+            fileset = fs.unions [
               ./src
               ./i18n.toml
               ./Cargo.toml
@@ -89,24 +81,41 @@
         };
 
         cargoArtifacts = craneLib.buildDepsOnly craneArgs;
-        cosmic-comp = craneLib.buildPackage (craneArgs // {inherit cargoArtifacts;});
       in {
-        apps.cosmic-comp = {
-          type = "app";
-          program = lib.getExe self'.packages.default;
-        };
-
-        checks.cosmic-comp = cosmic-comp;
-        packages.default = cosmic-comp;
+        cosmic-comp = craneLib.buildPackage (craneArgs // {inherit cargoArtifacts;});
 
-        devShells.default = craneLib.devShell {
-          LD_LIBRARY_PATH = lib.makeLibraryPath (
-            __concatMap (d: d.runtimeDependencies) (__attrValues self'.checks)
-          );
+        default = self.packages.${system}.cosmic-comp;
+      })
+      pkgsFor;
 
-          # include build inputs
-          inputsFrom = [cosmic-comp];
-        };
+    apps = eachSystem (system: {
+      cosmic-comp = {
+        type = "app";
+        program = lib.getExe self.packages.${system}.default;
       };
-    };
+
+      default = self.apps.${system}.cosmic-comp;
+    });
+
+    checks = eachSystem (system: {
+      inherit (self.packages.${system}) cosmic-comp;
+    });
+
+    devShells =
+      lib.mapAttrs (
+        system: pkgs: let
+          craneLib = crane.mkLib pkgs;
+        in {
+          default = craneLib.devShell {
+            LD_LIBRARY_PATH = lib.makeLibraryPath (
+              builtins.concatMap (d: d.runtimeDependencies) (builtins.attrValues self.checks.${system})
+            );
+
+            # include build inputs
+            inputsFrom = [self.packages.${system}.cosmic-comp];
+          };
+        }
+      )
+      pkgsFor;
+  };
 }