3 id="regexp">The regexp package</h3>

<p>
The <a href="/pkg/regexp/"><code>regexp</code></a> package has been rewritten.
It has the same interface but the specification of the regular expressions
it supports has changed from the old "egrep" form to that of
<a href="http://code.google.com/p/re2/">RE2</a>.
</p>

<p>
<em>Updating</em>:
Code that uses the package should have its regular expressions checked by hand.
</p>

<h3 id="runtime">The runtime package</h3>

<p>
In Go 1, much of the API exported by packag