sigexp</I>.</P>



<?php section("packages", "dynamic typing") ?>

<P>The most fundamental extension with respect to the typing discipline of SML
is the <TT>package</TT> type. Values of that type may encapsulate arbitrary
values (or modules) along with their type (resp., signature), which is dynamically checked upon
extraction of the value. Packages provide a rich form of dynamic typing within
the statically typed framework of ML. See the section on <A
href="packages.html">packages</A>.</P>


<?php footing(