Split home-manager config into modules

nix/modules/direnv.nix

@@ -0,0 +1,16 @@
+{ config, lib, pkgs, ... }:
+{
+  programs.direnv.enable = true;
+  programs.direnv.nix-direnv.enable = true;
+  programs.direnv.stdlib = ''
+    # From https://github.com/direnv/direnv/wiki/Customizing-cache-location
+    : ''${XDG_CACHE_HOME:=$HOME/.cache}
+    declare -A direnv_layout_dirs
+    direnv_layout_dir() {
+        echo "''${direnv_layout_dirs[$PWD]:=$(
+          local path="''${PWD//[^a-zA-Z0-9]/-}"
+          echo "$XDG_CACHE_HOME/direnv/layouts/''${path:1}"
+        )}"
+    }
+'';
+}