diff --git a/TODO b/TODO
index aaa00dc2..c3f4731c 100644
--- a/TODO
+++ b/TODO
@@ -1,4 +1,5 @@
 # -*- mode: org -*-
+#+STARTUP: nofold
 
 * Documentation
   Convert to YARD, Markdown
diff --git a/lib/haml.rb b/lib/haml.rb
index 945eae44..8e038c24 100644
--- a/lib/haml.rb
+++ b/lib/haml.rb
@@ -711,6 +711,8 @@ require 'haml/version'
 # [javascript] Surrounds the filtered text with <script> and CDATA tags.
 #              Useful for including inline Javascript.
 #
+# [cdata]      Surrounds the filtered text with CDATA tags.
+#
 # [escaped]    Works the same as plain, but HTML-escapes the text
 #              before placing it in the document.
 #
diff --git a/lib/haml/filters.rb b/lib/haml/filters.rb
index 4dfdbbae..3b0c3fdb 100644
--- a/lib/haml/filters.rb
+++ b/lib/haml/filters.rb
@@ -32,7 +32,6 @@ module Haml
       def self.included(base) # :nodoc:
         Filters.defined[base.name.split("::").last.downcase] = base
         base.extend(base)
-        base.instance_variable_set "@lazy_requires", nil
       end
 
       # Takes a string, the source text that should be passed to the filter,
diff --git a/lib/sass/css.rb b/lib/sass/css.rb
index cbada38f..d93bb1ff 100644
--- a/lib/sass/css.rb
+++ b/lib/sass/css.rb
@@ -19,7 +19,7 @@ module Sass
 
     class RuleNode
       def to_sass(tabs, opts = {})
-        str = "\n#{'  ' * tabs}#{rule}#{children.any? { |c| c.is_a? AttrNode } ? "\n" : ''}"
+        str = "\n#{'  ' * tabs}#{rules.first}#{children.any? { |c| c.is_a? AttrNode } ? "\n" : ''}"
 
         children.each do |child|
           str << "#{child.to_sass(tabs + 1, opts)}"
@@ -229,8 +229,8 @@ module Sass
     # but it's necessary to get nesting to work properly.
     def expand_commas(root)
       root.children.map! do |child|
-        next child unless Tree::RuleNode === child && child.rule.include?(',')
-        child.rule.split(',').map do |rule|
+        next child unless Tree::RuleNode === child && child.rules.first.include?(',')
+        child.rules.first.split(',').map do |rule|
           node = Tree::RuleNode.new(rule.strip)
           node.children = child.children
           node
@@ -276,10 +276,10 @@ module Sass
       rules = OrderedHash.new
       root.children.select { |c| Tree::RuleNode === c }.each do |child|
         root.children.delete child
-        first, rest = child.rule.scan(/^(&?(?: .|[^ ])[^.#: \[]*)([.#: \[].*)?$/).first
+        first, rest = child.rules.first.scan(/^(&?(?: .|[^ ])[^.#: \[]*)([.#: \[].*)?$/).first
         rules[first] ||= Tree::RuleNode.new(first)
         if rest
-          child.rule = "&" + rest
+          child.rules = ["&" + rest]
           rules[first] << child
         else
           rules[first].children += child.children
@@ -305,7 +305,7 @@ module Sass
     def remove_parent_refs(root)
       root.children.each do |child|
         if child.is_a?(Tree::RuleNode)
-          child.rule.gsub! /^& +/, ''
+          child.rules.first.gsub! /^& +/, ''
           remove_parent_refs child
         end
       end
@@ -342,10 +342,10 @@ module Sass
       while rule.children.size == 1 && rule.children.first.is_a?(Tree::RuleNode)
         child = rule.children.first
 
-        if child.rule[0] == ?&
-          rule.rule = child.rule.gsub /^&/, rule.rule
+        if child.rules.first[0] == ?&
+          rule.rules = [child.rules.first.gsub(/^&/, rule.rules.first)]
         else
-          rule.rule = "#{rule.rule} #{child.rule}"
+          rule.rules = ["#{rule.rules.first} #{child.rules.first}"]
         end
 
         rule.children = child.children
@@ -374,7 +374,7 @@ module Sass
         next child unless child.is_a?(Tree::RuleNode)
 
         if prev_rule && prev_rule.children == child.children
-          prev_rule.rule << ", #{child.rule}"
+          prev_rule.rules.first << ", #{child.rules.first}"
           next nil
         end
 
diff --git a/lib/sass/engine.rb b/lib/sass/engine.rb
index e80ad009..74d2cb36 100644
--- a/lib/sass/engine.rb
+++ b/lib/sass/engine.rb
@@ -118,12 +118,6 @@ module Sass
     rescue SyntaxError => e; e.add_metadata(@options[:filename], @line)
     end
 
-    protected
-
-    def environment
-      @environment
-    end
-
     private
 
     def tabulate(string)
@@ -399,7 +393,7 @@ END
         raise SyntaxError.new("Invalid variable \"#{arg}\".", @line) unless arg =~ Script::VALIDATE
         raise SyntaxError.new("Required arguments must not follow optional arguments \"#{arg}\".", @line) if default_arg_found && !default
         default = parse_script(default, :offset => line.offset + line.text.index(default)) if default
-        { :name => arg[1..-1], :default_value => default }
+        [arg[1..-1], default]
       end
       Tree::MixinDefNode.new(name, args)
     end
diff --git a/lib/sass/environment.rb b/lib/sass/environment.rb
index a3a24f54..a67160b5 100644
--- a/lib/sass/environment.rb
+++ b/lib/sass/environment.rb
@@ -22,12 +22,20 @@ module Sass
         end
 
         def set_#{name}(name, value)
-          if @parent && @parent.#{name}(name)
-            @parent.set_#{name}(name, value)
-          else
+          @#{name}s[name] = value unless try_set_#{name}(name, value)
+        end
+
+        def try_set_#{name}(name, value)
+          if @#{name}s.include?(name)
             @#{name}s[name] = value
+            true
+          elsif @parent
+            @parent.try_set_#{name}(name, value)
+          else
+            false
           end
         end
+        protected :try_set_#{name}
 
         def set_local_#{name}(name, value)
           @#{name}s[name] = value
diff --git a/lib/sass/tree/mixin_node.rb b/lib/sass/tree/mixin_node.rb
index 8985dd3d..14602344 100644
--- a/lib/sass/tree/mixin_node.rb
+++ b/lib/sass/tree/mixin_node.rb
@@ -18,14 +18,15 @@ Mixin #{@name} takes #{mixin.args.size} argument#{'s' if mixin.args.size != 1}
  but #{@args.size} #{@args.size == 1 ? 'was' : 'were'} passed.
 END
 
-      environment = mixin.args.zip(@args).inject(Sass::Environment.new(mixin.environment)) do |env, (arg, value)|
-        env.set_local_var(arg[:name],
+      environment = mixin.args.zip(@args).
+        inject(Sass::Environment.new(mixin.environment)) do |env, ((name, default), value)|
+        env.set_local_var(name,
           if value
             value.perform(environment)
-          elsif arg[:default_value]
-            arg[:default_value].perform(env)
+          elsif default
+            default.perform(env)
           end)
-        raise Sass::SyntaxError.new("Mixin #{@name} is missing parameter !#{arg[:name]}.") unless env.var(arg[:name])
+        raise Sass::SyntaxError.new("Mixin #{@name} is missing parameter !#{name}.") unless env.var(name)
         env
       end
       mixin.tree.map {|c| c.perform(environment)}.flatten
diff --git a/lib/sass/tree/rule_node.rb b/lib/sass/tree/rule_node.rb
index 8360da0c..71787078 100644
--- a/lib/sass/tree/rule_node.rb
+++ b/lib/sass/tree/rule_node.rb
@@ -12,14 +12,6 @@ module Sass::Tree
       super()
     end
 
-    def rule
-      rules.first
-    end
-
-    def rule=(rule)
-      self.rules = [rule]
-    end
-
     def ==(other)
       self.class == other.class && rules == other.rules && super
     end