flake: Convert to flake-parts

improves compositionality

flake.nix

@@ -2,44 +2,43 @@
   description = "A core language for rule-based hardware design";
 
   inputs = {
-    flake-utils.url = "github:numtide/flake-utils";
+    flake-parts.url = "github:hercules-ci/flake-parts";
     makes.url = "github:fluidattacks/makes/24.02";
     nixpkgs.url = "github:nixos/nixpkgs/release-24.05";
   };
 
-  outputs = {
-    self,
-    flake-utils,
-    makes,
-    nixpkgs,
-    ...
-  }:
-    with flake-utils.lib;
-      eachDefaultSystem (system: let
-        pkgs = import nixpkgs {
+  outputs = { self, flake-parts, makes, nixpkgs, ... } @ inputs:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      # Original flake.outputs attribute set. Everything in this set behaves like
+      # usual flake outputs.
+      flake = {
+        # NOTE: To use this flake, apply the following overlay to nixpkgs and use
+        # koika from its respective coqPackages_VER attribute set!
+        # See _module.args.pkgs = ... below for an example!
+        overlays.default = import ./overlay.nix;
+      };
+      systems = [ "x86_64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      perSystem = { inputs', self', system, pkgs, ... }: {
+        _module.args.pkgs = import inputs.nixpkgs {
           inherit system;
-          overlays = [self.overlays.default];
+          overlays = [ inputs.self.overlays.default ];
         };
-      in {
+
         checks = {
           koika = self.packages.${system}.default.override {
             doCheck = true;
           };
         };
 
-        devShells.default = self.checks.${system}.koika;
+        devShells.default = self'.checks.koika;
 
         packages = {
-          default = self.packages.${system}.coq8_18-koika;
+          default = self'.packages.coq8_18-koika;
           coq8_18-koika = pkgs.coqPackages_8_18.koika;
           coqDev-koika = pkgs.coqPackages_koika.koika;
         };
 
-        apps.makes = makes.apps.${system}.default;
-      })
-      // {
-        # NOTE: To use this flake, apply the following overlay to nixpkgs and use
-        # koika from its respective coqPackages_VER attribute set!
-        overlays.default = import ./overlay.nix;
+        apps.makes = inputs'.makes.apps.default;
       };
+    };
 }