Added info about do-notation to chapter functions/parentheses.

Author: Jonas Höglund

chapters/functions/parentheses.textile

@@ -12,10 +12,28 @@ h2. Solution
 
 Use parentheses anyway.
 
+Another alternative is to utilise the do-notation like so:
+{% highlight coffeescript %}
+notify = -> alert "Hello, user!"
+do notify if condition
+{% endhighlight %}
+
+This compiles to the following JavaScript:
+{% highlight javascript %}
+var notify;
+notify = function() {
+	return alert("Hello, user!");
+};
+if (condition) {
+	notify();
+}
+{% endhiglight %}
+
 h2. Discussion
 
 Like Ruby, CoffeeScript allows you to drop parentheses to method calls. Unlike Ruby, however, CoffeeScript treats a bare function name as the pointer to the function. The practical upshot of this is that if you give no arguments to a method, CoffeeScript cannot tell if you want to call the function or use it as a reference.
 
 Is this good or bad? It's just different. It creates an unexpected syntax case—parentheses aren't _always_ optional—but in exchange it gives you the ability to pass and receive functions fluently by name, something that's a bit klunky in Ruby.
 
-
+This usage of the do-notation is a neat approach for CoffeeScript with parenphobia.
+Some people simply prefer to write out the parentheses in the function call, though.