_negate</nobr></tt> to be instantiated with a function
type (see the C++ Standard &sect;14.3.1 &para;3).

<h4><tt>param_type</tt></h4>

<p>This is a type suitable for passing the function or function object
as a parameter to another function.  For example,

<blockquote><pre>
template &lt;class Predicate&gt;
class unary_negate : // ...
{
  public:
    explicit unary_negate(<strong>typename unary_traits&lt;Predicate&gt;::param_type</strong> x)
        :
        pred(x)
    {}
    // ...
};
</pre></blockquote>