plugins/which-key: move listOfLen to lib.types

Allows us to require a list to have a certain length for plugins that
request it.

lib/types.nix

@@ -81,6 +81,15 @@ rec {
 
   # Overridden when building the documentation
   eitherRecursive = either;
+
+  listOfLen =
+    elemType: len:
+    addCheck (listOf elemType) (v: builtins.length v == len)
+    // {
+      description = "list of ${toString len} ${
+        optionDescriptionPhrase (class: class == "noun" || class == "composite") elemType
+      }";
+    };
 }
 # Allow to do `with nixvimTypes;` instead of `with types;`
 // lib.types

plugins/utils/which-key.nix

@@ -10,15 +10,6 @@ let
   inherit (lib.nixvim) defaultNullOpts mkRaw toLuaObject;
   types = lib.nixvim.nixvimTypes;
 
-  listOfLen =
-    elemType: len:
-    types.addCheck (types.listOf elemType) (v: length v == len)
-    // {
-      description = "list of ${toString len} ${
-        types.optionDescriptionPhrase (class: class == "noun" || class == "composite") elemType
-      }";
-    };
-
   opt = options.plugins.which-key;
 in
 lib.nixvim.neovim-plugin.mkNeovimPlugin config {
@@ -332,7 +323,7 @@ lib.nixvim.neovim-plugin.mkNeovimPlugin config {
         Supports all available border types from `vim.api.keyset.win_config.border`.
       '';
 
-      padding = defaultNullOpts.mkNullable (listOfLen types.int 2) [
+      padding = defaultNullOpts.mkNullable (types.listOfLen types.int 2) [
         1
         2
       ] "Extra window padding, in the form `[top/bottom, right/left]`.";