autoload slim and maruku

lib/middleman/core_extensions/rendering.rb

@@ -1,8 +1,14 @@
 module Middleman::CoreExtensions::Rendering
   class << self
     def registered(app)
+      # Autoload
       require "coffee_script"
       
+      begin
+        require "slim"
+      rescue LoadError
+      end
+      
       # Activate custom renderers
       app.register Middleman::Renderers::Sass
       app.register Middleman::Renderers::Markdown

lib/middleman/renderers/markdown.rb

@@ -3,7 +3,13 @@ module Middleman::Renderers::Markdown
     def registered(app)
       app.send :include, InstanceMethods
       
+      begin
+        require "maruku"
+        app.set :markdown_engine, :maruku
+      rescue LoadError
         app.set :markdown_engine, nil
+      end
+
       app.set :markdown_engine_prefix, ::Tilt
       
       app.after_configuration do