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<h1>Cast as, Treat as</h1>
<p>The expression <code>E cast as T</code> converts the value of expression <code>E</code> to type
<code>T</code>. Whether T is a built-in type or a user-defined type, the
effect is exactly the same as using the constructor function <code>T (E)</code>.</p>
<p>The expression <code>E treat as T</code> is designed for environments that perform static type
checking. Saxon doesn't do static type checking, so this expression has very little use, except to
document an assertion that the expression <code>E</code> is of a particular type. A run-time failure
will be reported if the value of <code>E</code> is not of type <code>T</code>; no attempt is made
to convert the value to this type.</p>
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