is <function>eql</> to the old value. Conforming to this specification
is a nuisance when the "constant" value is only constant under some
weaker test like <function>string=</> or <function>equal</>. It's
-especially annoying because <function>defconstant</> takes effect
+especially annoying because, in &SBCL;, <function>defconstant</> takes effect
not only at load time but also at compile time, so that just
compiling and loading reasonable code like
<programlisting>(defconstant +foobyte+ '(1 4))</>
<function>defconstant</> either with <function>defparameter</> or
with a customized macro which does the right thing, possibly along the
lines of the <function>defconstant-eqx</> macro used internally in the
-implementation of SBCL itself.</para>
+implementation of &SBCL; itself. In circumstances where this is not
+appropriate, the programmer can handle the condition type
+<errortype>sb-ext:defconstant-uneql</errortype>, and choose either the
+<action>continue</action> or <action>abort</action> restart as
+appropriate.</para>
<para>&SBCL; gives style warnings about various kinds of perfectly
legal code, e.g.
between multiple Lisp processes. is less important with modern
generational garbage collectors. </para>
-<para>The <function>sb-ext:truly-the</> operator does what the
-<function>cl:the</> operator does in a more conventional
-implementation of &CommonLisp;, declaring the type of its argument
-without any runtime checks. (Ordinarily in &SBCL;, any type
-declaration is treated as an assertion and checked at runtime.)</para>
+<para>The <function>sb-ext:truly-the</> declares the type of the
+result of the operations, producing its argument; the declaration is
+not checked. In short: don't use it.</para>
<para>The <function>sb-ext:freeze-type</> declaration declares that a
type will never change, which can make type testing
is <emphasis>not</> appropriate for functions like <function>aref</>,
which can change their return values when the underlying data are
changed.</para>
+<!-- FIXME: This declaration does not seem to be supported in the --
+ -- current compiler. -->
</sect2>
</sect1>
-</chapter>
\ No newline at end of file
+</chapter>