flake: clean up by moving implementation to utils

Fixes #28 by adding an `externOverlays` list to easily import overlays
from external flakes.

flake.nix

@@ -13,76 +13,43 @@
       inherit (builtins) attrNames attrValues readDir;
       inherit (nixos) lib;
       inherit (lib) removeSuffix recursiveUpdate genAttrs filterAttrs;
-      inherit (utils) pathsToImportedAttrs;
+      inherit (utils) pathsToImportedAttrs genPkgset overlayPaths modules
+        genPackages;
 
       utils = import ./lib/utils.nix { inherit lib; };
 
       system = "x86_64-linux";
 
-      pkgImport = pkgs:
+      externOverlays = [ ];
-        import pkgs {
+
-          inherit system;
+      pkgset =
-          overlays = attrValues self.overlays;
+        let overlays = (attrValues self.overlays) ++ externOverlays; in
-          config = { allowUnfree = true; };
+        genPkgset {
+          inherit master nixos overlays system;
         };
-
-      pkgset = {
-        osPkgs = pkgImport nixos;
-        pkgs = pkgImport master;
-      };
-
     in
     with pkgset;
     {
       nixosConfigurations =
         import ./hosts (recursiveUpdate inputs {
           inherit lib pkgset system utils;
-        }
+        });
-        );
 
       devShell."${system}" = import ./shell.nix {
-        inherit pkgs;
+        pkgs = osPkgs;
       };
 
       overlay = import ./pkgs;
 
-      overlays =
+      overlays = pathsToImportedAttrs overlayPaths;
-        let
-          overlayDir = ./overlays;
-          fullPath = name: overlayDir + "/${name}";
-          overlayPaths = map fullPath (attrNames (readDir overlayDir));
-        in
-        pathsToImportedAttrs overlayPaths;
 
-      packages."${system}" =
+      packages."${system}" = genPackages {
-        let
+        overlay = self.overlay;
-          packages = self.overlay osPkgs osPkgs;
+        overlays = self.overlays;
-          overlays = lib.filterAttrs (n: v: n != "pkgs") self.overlays;
+        pkgs = osPkgs;
-          overlayPkgs =
+      };
-            genAttrs
-              (attrNames overlays)
-              (name: (overlays."${name}" osPkgs osPkgs)."${name}");
-        in
-        recursiveUpdate packages overlayPkgs;
 
-      nixosModules =
+      nixosModules = modules;
-        let
-          # binary cache
-          cachix = import ./cachix.nix;
-          cachixAttrs = { inherit cachix; };
-
-          # modules
-          moduleList = import ./modules/list.nix;
-          modulesAttrs = pathsToImportedAttrs moduleList;
-
-          # profiles
-          profilesList = import ./profiles/list.nix;
-          profilesAttrs = { profiles = pathsToImportedAttrs profilesList; };
-
-        in
-        recursiveUpdate
-          (recursiveUpdate cachixAttrs modulesAttrs)
-          profilesAttrs;
 
       templates.flk.path = ./.;
       templates.flk.description = "flk template";

hosts/default.nix

@@ -11,7 +11,7 @@
 let
   inherit (utils) recImport;
   inherit (builtins) attrValues removeAttrs;
-  inherit (pkgset) osPkgs pkgs;
+  inherit (pkgset) osPkgs unstablePkgs;
 
   config = hostName:
     lib.nixosSystem {
@@ -37,7 +37,7 @@ let
                 "home-manager=${home}"
               ];
 
-            nixpkgs = { pkgs = osPkgs; };
+            nixpkgs.pkgs = osPkgs;
 
             nix.registry = {
               master.flake = master;
@@ -52,7 +52,7 @@ let
           overrides = {
             nixpkgs.overlays =
               let
-                override = import ../pkgs/override.nix pkgs;
+                override = import ../pkgs/override.nix unstablePkgs;
 
                 overlay = pkg: final: prev: {
                   "${pkg.pname}" = pkg;

lib/utils.nix

@@ -2,7 +2,8 @@
 let
   inherit (builtins) attrNames isAttrs readDir listToAttrs;
 
-  inherit (lib) filterAttrs hasSuffix mapAttrs' nameValuePair removeSuffix;
+  inherit (lib) filterAttrs hasSuffix mapAttrs' nameValuePair removeSuffix
+    recursiveUpdate genAttrs;
 
   # mapFilterAttrs ::
   #   (name -> value -> bool )
@@ -13,21 +14,11 @@ let
   # Generate an attribute set by mapping a function over a list of values.
   genAttrs' = values: f: listToAttrs (map f values);
 
-in
+  pkgImport = { pkgs, system, overlays }:
-{
+    import pkgs {
-  inherit mapFilterAttrs genAttrs';
+      inherit system overlays;
-
+      config = { allowUnfree = true; };
-  recImport = { dir, _import ? base: import "${dir}/${base}.nix" }:
+    };
-    mapFilterAttrs
-      (_: v: v != null)
-      (n: v:
-        if n != "default.nix" && hasSuffix ".nix" n && v == "regular"
-        then
-          let name = removeSuffix ".nix" n; in nameValuePair (name) (_import name)
-
-        else
-          nameValuePair ("") (null))
-      (readDir dir);
 
   # Convert a list to file paths to attribute set
   # that has the filenames stripped of nix extension as keys
@@ -38,4 +29,68 @@ in
       value = import path;
     });
 
+in
+{
+  inherit mapFilterAttrs genAttrs' pkgImport pathsToImportedAttrs;
+
+  genPkgset = { master, nixos, overlays, system }:
+    {
+      osPkgs = pkgImport {
+        inherit system overlays;
+        pkgs = nixos;
+      };
+
+      unstablePkgs = pkgImport {
+        inherit system overlays;
+        pkgs = master;
+      };
+    };
+
+  overlayPaths =
+    let
+      overlayDir = ../overlays;
+      fullPath = name: overlayDir + "/${name}";
+    in
+    map fullPath (attrNames (readDir overlayDir));
+
+  recImport = { dir, _import ? base: import "${dir}/${base}.nix" }:
+    mapFilterAttrs
+      (_: v: v != null)
+      (n: v:
+        if n != "default.nix" && hasSuffix ".nix" n && v == "regular"
+        then
+          let name = removeSuffix ".nix" n; in nameValuePair (name) (_import name)
+        else
+          nameValuePair ("") (null))
+      (readDir dir);
+
+  modules =
+    let
+      # binary cache
+      cachix = import ../cachix.nix;
+      cachixAttrs = { inherit cachix; };
+
+      # modules
+      moduleList = import ../modules/list.nix;
+      modulesAttrs = pathsToImportedAttrs moduleList;
+
+      # profiles
+      profilesList = import ../profiles/list.nix;
+      profilesAttrs = { profiles = pathsToImportedAttrs profilesList; };
+    in
+    recursiveUpdate
+      (recursiveUpdate cachixAttrs modulesAttrs)
+      profilesAttrs;
+
+  genPackages = { overlay, overlays, pkgs }:
+    let
+      packages = overlay pkgs pkgs;
+      overlays' = lib.filterAttrs (n: v: n != "pkgs") overlays;
+      overlayPkgs =
+        genAttrs
+          (attrNames overlays')
+          (name: (overlays'."${name}" pkgs pkgs)."${name}");
+    in
+    recursiveUpdate packages overlayPkgs;
+
 }