home: fish: setup wrapper around flake lock

home/fish.nix

@@ -6,6 +6,20 @@ in
   options.my.home.fish.enable = lib.mkEnableOption "Fish shell";
 
   config = lib.mkIf cfg.enable {
-    programs.fish.enable = true;
+    programs.fish = {
+      enable = true;
+      functions = {
+        nfl = {
+          body = ''
+            set -l flags "--commit-lock-file"
+            for flake in $argv
+                set -a flags "--update-input" "$flake"
+            end
+            nix flake lock $flags
+          '';
+          description = "convenience wrapper around `nix flake lock` to only update certain flake inputs";
+        };
+      };
+    };
   };
 }