mkFlake: init

flake.nix

@@ -45,5 +45,6 @@
           "ekala-corepkgs.cachix.org-1:DcZV+vegWoEzacbSdXFXU4S7728C0eS9RfGpKeyHd6w="
         ];
       };
+      mkFlake = import ./lib/mk-flake.nix;
     };
 }

lib/mk-flake.nix

@@ -0,0 +1,48 @@
+{
+  overlays ? [ ],
+  config ? { },
+  packages ? null,
+  devShells ? null,
+  checks ? null,
+  formatter ? null,
+  apps ? null,
+  checks ? null,
+  hydraJobs ? null,
+  systems ? [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ],
+  # TODO: support pkgsModules
+}:
+
+let
+  # TODO: don't depend on lib
+  forAllSystems = lib.genAttrs systems;
+  optionalAttrs = pred: attrs: if pred then attrs else { };
+  optionalOutput = outputFunc: outputName: optionalAttrs (output != null) {
+    ${outputName} = forallSystem (system: outputFunc legacyPackages.${sytem});
+  };
+  packages = forallSystems (system: packages legacyPackages.${system});
+
+  legacyPackages = forAllSystems (system: import ../. {
+    inherit system config;
+  });
+  assertMsg = pred: msg: pred || throw msg;
+  assertFuncDefined = func: name: assertMsg (func != null -> builtins.isFunction func) "${name} must be a function";
+  # Avoid having people do this boilerplate
+  mkApps = builtins.mapAttrs (_: v: { type = "app"; program = v; })
+  apps' = if apps == null then null else x: mkApps (apps x);
+in
+
+assert assertFuncDefined packages "packages";
+assert assertFuncDefined devShells "devShells";
+assert assertFuncDefined checks "checks";
+assert assertFuncDefined formatter "formatter";
+assert assertFuncDefined apps "apps";
+assert assertFuncDefined hydraJobs "hydraJobs";
+
+{
+  inherit legacyPackages;
+} // optionalOutput packages "packages"
+// optionalOutput devShells "devShells"
+// optionalOutput checks "checks"
+// optionalOutput formatter "formatter"
+// optionalOutput apps' "apps"
+// optionalOutput hydraJobs "hydraJobs"