Set leader key first

extraConfig is included after the plugin config
=> Let's create a fake plugin derivation, so that we can use it to set
configuration before the plugin configurations.

users/jalr/modules/neovim.nix

@@ -1,13 +1,14 @@
 { lib, nixosConfig, config, pkgs, ... }:
+
+let
+  fakePlugin = pkgs.runCommand "neovim-fake-plugin" { } "mkdir $out";
+in
 {
   programs.neovim = {
     enable = true;
     vimAlias = true;
     defaultEditor = true;
     extraConfig = ''
-      " use space as leader
-      let mapleader = " "
-
       colorscheme NeoSolarized
 
       """""""""""""""""
@@ -66,8 +67,17 @@
       lua require('init')
     '';
 
+    plugins = [
+      {
+        plugin = fakePlugin;
+        config = ''
+          " use space as leader
+          let mapleader = " "
+        '';
+      }
+    ] ++
     # nix-env -f '<nixpkgs>' -qaP -A vimPlugins
-    plugins = with pkgs.vimPlugins; [
+    (with pkgs.vimPlugins; [
       #Valloric/MatchTagAlways
       #frankier/neovim-colors-solarized-truecolor-only
       #nvie/vim-rst-tables
@@ -86,7 +96,7 @@
           config = "lua require('lsp_signature').setup()";
         }
       )
-    ];
+    ]);
   };
 
   xdg.configFile."nvim/lua/init.lua".text = builtins.concatStringsSep "\n" (