modules: add a sane.programs interface which i can use going forward in place of sane.packages

modules/default.nix

@@ -6,6 +6,7 @@
     ./fs
     ./ids.nix
     ./packages.nix
+    ./programs.nix
     ./image.nix
     ./persist
     ./services

modules/programs.nix

@@ -0,0 +1,88 @@
+{ config, lib, pkgs, sane-lib, ... }:
+let
+  inherit (builtins) elem map;
+  inherit (lib) mapAttrs mapAttrsToList mkDefault mkIf mkMerge mkOption optionalAttrs types;
+  cfg = config.sane.programs;
+  pkgSpec = types.submodule ({ name, ... }: {
+    options = {
+      package = mkOption {
+        type = types.package;
+      };
+      enableFor.system = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          place this program on the system PATH
+        '';
+      };
+      enableFor.user = mkOption {
+        type = types.attrsOf types.bool;
+        default = {};
+        description = ''
+          place this program on the PATH for some specified user(s).
+        '';
+      };
+      suggestedPrograms = mkOption {
+        type = types.listOf types.str;
+        default = [];
+        description = ''
+          list of other programs a user may want to enable alongside this one.
+          for example, the gnome desktop environment would suggest things like its settings app.
+        '';
+      };
+      enableSuggested = mkOption {
+        type = types.bool;
+        default = true;
+      };
+      dir = mkOption {
+        type = types.listOf types.str;
+        default = [];
+        description = "list of home-relative paths to persist for this package";
+      };
+      private = mkOption {
+        type = types.listOf types.str;
+        default = [];
+        description = "list of home-relative paths to persist (in encrypted format) for this package";
+      };
+    };
+
+    config = {
+      # package can be inferred by the attr name, allowing shorthand like
+      # sane.packages.nano.enable = true;
+      pkg = mkIf (pkgs ? name) (mkDefault pkgs."${name}");
+
+      # enable this package if it's in the `suggestedPrograms` of any other enabled program
+      enableFor = mkMerge (mapAttrsToList (_otherName: otherPkg:
+        optionalAttrs
+          (otherPkg.enableSuggested && elem name otherPkg.suggestedPrograms)
+          (mkDefault otherPkg.enableFor)
+      ) cfg);
+    };
+  });
+  toPkgSpec = types.coercedTo types.package (p: { pkg = p; }) pkgSpec;
+
+  configs = mapAttrsToList (_name: p: {
+    # conditionally add to system PATH
+    environment.systemPackages = mkIf p.enableFor.system [ p.package ];
+    # conditionally add to user(s) PATH
+    users.users = mapAttrs (user: en: optionalAttrs en {
+      "${user}".packages = [ p ];
+    }) p.enableFor.users;
+  }) cfg;
+in
+{
+  options = {
+    sane.programs = mkOption {
+      type = types.attrsOf toPkgSpec;
+      default = {};
+    };
+  };
+
+  config =
+    let
+      take = f: {
+        environment.systemPackages = f.environment.systemPackages;
+        users.users = f.users.users;
+      };
+    in take (sane-lib.mkTypedMerge take configs);
+}