you'll see in most OO systems, and there are a number of lesser
differences as well. This book tends to help with the culture shock.
</para></listitem>
- <listitem><para></para></listitem>
</itemizedlist>
</para>
at their command prompts. The extensions for functions which
don't have their own command prompt (like <function>trace</>
does) are described in their documentation strings,
- unless your &SBCL was compiled with an option not
+ unless your &SBCL; was compiled with an option not
to include documentation strings, in which case the doc strings
are only readable in the source code.</para></listitem>
<listitem><para>Some low-level information describing the
likely to be fixed, tuned, or added. </para>
<para>&SBCL; is descended from &CMUCL;, which is itself descended from
-Spice Lisp. Early implementations for the Mach operating system on the
-IBM RT, back in the 1980s. Design decisions from that time are still
-reflected in the current implementation:
+Spice Lisp, including early implementations for the Mach operating
+system on the IBM RT, back in the 1980s. Design decisions from that
+time are still reflected in the current implementation:
<itemizedlist>
<listitem><para>The system expects to be loaded into a
fixed-at-compile-time location in virtual memory, and also expects
<listitem><para>A word is a 32-bit quantity. The system has been
ported to many processor architectures without altering this
basic principle. Some hacks allow the system to run on the Alpha
- chip (a 64-bit architecture) but the assumption that a word is
+ chip (a 64-bit architecture) but even there 32-bit words are
+ used. The assumption that a word is
32 bits wide is implicit in hundreds of places in the
system.</para></listitem>
<listitem><para>The system is implemented as a C program which is
to improve in these areas (and has already improved in some other
areas), but it takes a while.</para>
-<para>The &SBCL; GC, like the GC on the X86 port of &CMUCL;, is
-<emphasis>conservative</>. This means that it doesn't maintain a
+<para>On the x86, &SBCL; like the X86 port of &CMUCL;, uses a
+<emphasis>conservative</> GC. This means that it doesn't maintain a
strict separation between tagged and untagged data, instead treating
some untagged data (e.g. raw floating point numbers) as
possibly-tagged data and so not collecting any Lisp objects that they
various bizarre bootstrapping hangups, especially when a major change
is made to the system. It also makes the connection between the
current source code and the current executable more tenuous than in
-any other software system I'm aware of -- it's easy to accidentally
+other software systems -- it's easy to accidentally
<quote>build</> a &CMUCL; system containing characteristics not
reflected in the current version of the source code.</para>
<para>Other major changes since the fork from &CMUCL; include
<itemizedlist>
<listitem><para>&SBCL; has dropped support for many &CMUCL; extensions,
- (e.g. remote procedure call, Unix system interface, and X11
- interface).</para></listitem>
+ (e.g. IP networking, remote procedure call, Unix system interface, and X11
+ interface). Some of these are now available as contributed or
+ third-party modules.</para></listitem>
<listitem><para>&SBCL; has deleted or deprecated
some nonstandard features and code complexity which helped
efficiency at the price of maintainability. For example, the
projects / sbcl.git / blobdiff