<p>
A function type denotes the set of all functions with the same parameter and result types.
The <a href="#Representation_of_values">value</a> of an uninitialized variable of function
type is <code>nil</code>.
</p>

<pre class="ebnf">
FunctionType  = "func" Signature .
Signature     = Parameters [ Result ] .
Result        = Parameters | Type .
Parameters    = "(" [ ParameterList [ "," ] ] ")" .