1.0.13.22: text tweaks

[sbcl.git] / doc / sbcl.1

diff --git a/doc/sbcl.1 b/doc/sbcl.1
index 9161690..621eaef 100644 (file)
--- a/doc/sbcl.1
+++ b/doc/sbcl.1
@@ -16,7 +16,7 @@
 .TH SBCL 1 "$Date$"
 .AT 3
 .SH NAME
 .TH SBCL 1 "$Date$"
 .AT 3
 .SH NAME

-SBCL -- "Steel Bank Common Lisp"
+SBCL -- Steel Bank Common Lisp

 
 .SH DESCRIPTION
 
 
 .SH DESCRIPTION
 

@@ -25,381 +25,477 @@ the free CMU CL programming environment. (The name is intended to
 acknowledge the connection: steel and banking are the industries where
 Carnegie and Mellon made the big bucks.)
 
 acknowledge the connection: steel and banking are the industries where
 Carnegie and Mellon made the big bucks.)
 

-.SH COMMAND LINE SYNTAX
+.SH LICENSING

 
 

-Command line syntax can be considered an advanced topic; for ordinary
-interactive use, no command line arguments should be necessary.
+It is free software, mostly in the public domain, but with some
+subsystems under BSD-style licenses which allow modification and
+reuse as long as credit is given. It is provided "as is", with no
+warranty of any kind.

 
 

-In order to understand the command line argument syntax for SBCL, it
-is helpful to understand that the SBCL system is implemented as two
-components, a low-level runtime environment written in C and a
-higher-level system written in Common Lisp itself. Some command line
-arguments are processed during the initialization of the low-level
-runtime environment, some command line arguments are processed during
-the initialization of the Common Lisp system, and any remaining
-command line arguments are passed on to user code.
+For more information about license issues, see the COPYING file in
+the distribution. For more information about history, see the 
+CREDITS file in the distribution.

 
 

-The full, unambiguous syntax for invoking SBCL at the command line is
-.TP 3
-.B sbcl [runtime options] --end-runtime-options [toplevel options] --end-toplevel-options [user options]
-.PP
+.SH RUNNING SBCL

 
 

-For convenience, the --end-runtime-options and --end-toplevel-options
-elements can be omitted. Omitting these elements can be convenient
-when you are running the program interactively, and you can see that
-no ambiguities are possible with the option values you are using.
-Omitting these elements is probably a bad idea for any batch file
-where any of the options are under user control, since it makes it
-impossible for SBCL to detect erroneous command line input, so that
-erroneous command line arguments will be passed on to the user program
-even if they was intended for the runtime system or the Lisp system.
+To run SBCL, type "sbcl" at the command line with no arguments. (SBCL
+understands command line arguments, but you probably won't need to use
+them unless you're a fairly advanced user. If you are, you should read
+the COMMAND LINE SYNTAX section, below.) You should see some startup
+messages, then a prompt ("\f(CR*\fR").  Type a Lisp expression at the prompt,
+and SBCL will read it, execute it, print any values returned, give you
+another prompt, and wait for your next input.  For example,
+\f(CR
+  * (+ 1 2 3)

 
 

-Supported runtime options are
-.TP 3
-.B --core <corefilename>
-Run the specified Lisp core file instead of the default. (See the FILES
-section.) Note that if the Lisp core file is a user-created core file, it may
-run a nonstandard toplevel which does not recognize the standard toplevel
-options.
-.TP 3
-.B --noinform
-Suppress the printing of any banner or other informational message at
-startup. (This makes it easier to write Lisp programs which work in
-Unix pipelines. See also the "--noprogrammer" and "--noprint" options.)
-.PP
+  6
+  * (funcall (lambda (x y) (list x y y)) :toy :choo)

 
 

-In the future, runtime options may be added to control behavior such
-as lazy allocation of memory.
+  (:TOY :CHOO :CHOO)
+  * "Hello World"

 
 

-Runtime options, including any --end-runtime-options option,
-are stripped out of the command line before the
-Lisp toplevel logic gets a chance to see it.
+  "Hello World"
+  *
+\fR

 
 

-Supported toplevel options for the standard SBCL core are
+Many people like to run SBCL, like other Lisp systems, as a subprocess
+under Emacs. The Emacs "Slime" and "ilisp" modes provide many
+convenient features, like command line editing, tab completion, and
+various kinds of coupling between Common Lisp source files and the
+interactive SBCL subprocess, but they can be somewhat fragile with
+respect to packages and readtables, in which case SBCL in the Emacs
+"shell" mode can be a useful substitute.
+
+.SH OVERVIEW
+
+SBCL compiles Common Lisp to native code. (Even today, some 30 years
+after the MacLisp compiler, people will tell you that Lisp is an
+interpreted language. Ignore them.)
+
+SBCL aims for but has not completely achieved compliance with the ANSI
+standard for Common Lisp. More information about this is available in
+the BUGS section below.
+
+SBCL also includes various non-ANSI extensions, described more fully
+in the User Manual.  Some of these are in the base system and others
+are "contrib" modules loaded on request using \f(CRREQUIRE\fR.  For
+example, to load the \f(CRSB\-BSD\-SOCKETS\fR module that provides
+TCP/IP connectivity,
+\f(CR
+   * (require \(aqasdf)
+   * (require \(aqsb\-bsd\-sockets)
+\fR
+
+Many Lispy extensions have been retained from CMU CL:

 .TP 3
 .TP 3

-.B --sysinit <filename>
-Load filename instead of the default system-wide initialization file.
-(See the FILES section.) There is no special option to cause no
-system-wide initialization file to be read, but on a Unix system
-"--sysinit /dev/null" can be used to achieve the same effect.
+\--
+CMU-CL-style safe implementation of type declarations:
+"Declarations are assertions."

 .TP 3
 .TP 3

-.B --userinit <filename>
-Load filename instead of the default user initialization file. (See
-the FILES section.) There is no special option to cause no user
-initialization file to be read, but on a Unix system "--userinit
-/dev/null" can be used to achieve the same effect.
+\--
+the source level debugger (very similar to CMU CL's)

 .TP 3
 .TP 3

-.B --eval <command>
-After executing any initialization file, but before starting the
-read-eval-print loop on standard input, evaluate the command given.
-More than one --eval option can be used, and all will be executed, in
-the order they appear on the command line.
+\--
+the profiler (now somewhat different from CMU CL's)

 .TP 3
 .TP 3

-.B --noprint
-When ordinarily the toplevel "read-eval-print loop" would be executed,
-execute a "read-eval loop" instead, i.e. don't print a prompt and
-don't echo results. Combined with the --noinform runtime option, this
-makes it easier to write Lisp "scripts" which work in Unix pipelines.
+\--
+saving the state of the running SBCL process, producing a
+"core" file which can be restarted later
+.TP 3
+\--
+Gray streams (a de-facto standard system of overloadable CLOS classes
+whose instances can be used wherever ordinary ANSI streams can be used)

 .TP 3
 .TP 3

-.B --noprogrammer
-By default, a Common Lisp system tries to ask the programmer for help
-when it gets in trouble (by printing a debug prompt on *DEBUG-IO*).
-However, this is not useful behavior for a system running with no
-programmer available, and this option tries to set up more appropriate
-behavior for that situation. Thus we set *DEBUG-IO* to send its
-output to *ERROR-OUTPUT*, and to raise an error if any input is
-requested from it; and we set *DEBUGGER-HOOK* to output a backtrace,
-then exit the process with a failure code.
+\--
+weak pointers and finalization (which have unfortunately
+suffered from at least some code rot, so that \fIe.g.\fR weak hash
+tables don't work)

 .PP
 
 .PP
 

-Regardless of the order in which --sysinit, --userinit, and --eval
-options appear on the command line, the sysinit file, if it exists, is
-loaded first; then the userinit file, if it exists, is loaded; then
-any --eval commands are executed in sequence; then the read-eval-print
-loop is started on standard input. At any step, error conditions or
-commands such as SB-EXT:QUIT can cause execution to be terminated
-before proceeding to subsequent steps.
-
-Note that when running SBCL with the --core option, using a core file
-created by a user call to the SB-EXT:SAVE-LISP-AND-DIE, the toplevel
-options may be under the control of user code passed as arguments to
-SB-EXT:SAVE-LISP-AND-DIE. For this purpose, the --end-toplevel-options
-option itself can be considered a toplevel option, i.e. the user core,
-at its option, may not support it.
-
-In the standard SBCL startup sequence (i.e. with no user core
-involved) toplevel options and any --end-toplevel-options option are
-stripped out of the command line argument list before user code gets a
-chance to see it.
-
-.SH OVERVIEW
-
-SBCL aims for but has not reached ANSI compliance.
-
-SBCL compiles Lisp to native code, or optionally to more-compact but
-much slower byte code.
-
-SBCL's garbage collector is generational and conservative.
-
-SBCL includes a source level debugger, as well as the ANSI TRACE
-facility and a rudimentary profiler.
+Fundamental system interface extensions are also provided:
+.TP 3
+\--
+calling out to C code (a.k.a. FFI, foreign function interface,
+with very nearly the same interface as CMU CL)
+.TP 3
+\--
+some simple support for operations with a "scripting language" flavor,
+\fIe.g.\fR reading POSIX \f(CRargc\fR and \f(CRargv\fR, or executing a
+subprogram
+.PP

 
 .SH DIFFERENCES FROM CMU CL
 
 SBCL can be built from scratch using a plain vanilla ANSI Common Lisp
 system and a C compiler, and all of its properties are specified by
 
 .SH DIFFERENCES FROM CMU CL
 
 SBCL can be built from scratch using a plain vanilla ANSI Common Lisp
 system and a C compiler, and all of its properties are specified by

-the version of the source code that it was created from. (This clean
+the version of the source code that it was created from. This clean

 bootstrappability was the immediate motivation for forking off of the
 bootstrappability was the immediate motivation for forking off of the

-CMU CL development tree.) A variety of internal implementation
-differences are motivated by this.
+CMU CL development tree. A variety of implementation differences are
+motivated by this design goal.

 
 

-Maintenance work in SBCL since the fork has diverged in various
-details from the maintenance work in CMU CL. E.g. as of 2001-04-12,
-SBCL was more ANSI-compliant than CMU CL in various details such as
-support for PRINT-OBJECT and DESCRIBE-OBJECT, and SBCL's compiler was
-substantially better than CMU CL's at optimizing operations on
-non-simple vectors.
+Maintenance work in SBCL since the fork has diverged somewhat from the
+maintenance work in CMU CL. Many but not all bug fixes and
+improvements have been shared between the two projects, and sometimes
+the two projects disagree about what would be an improvement.

 
 

-Most extensions supported by CMU CL are not supported in SBCL,
+Most extensions supported by CMU CL have been unbundled from SBCL,

 including Motif support, the Hemlock editor, search paths, the
 including Motif support, the Hemlock editor, search paths, the

-low-level Unix interface, the WIRE protocol, multithreading support,
-various user-level macros and functions (e.g. LETF, ITERATE, MEMQ,
-REQUIRED-ARGUMENT), and many others.
+low-level Unix interface, the WIRE protocol, various user-level macros
+and functions (\fIe.g.\fR \f(CRLETF\fR, \f(CRITERATE\fR, \f(CRMEMQ\fR,
+\f(CRREQUIRED\-ARGUMENT\fR), and many others.

 
 

-SBCL has retained some extensions from parent CMU CL. Many of the
+SBCL inplements multithreading, but in a completely different fashion
+from CMU CL: see the User Manual for details. As of 1.0.13 this is
+still considered beta-quality and must be explicitly enabled at build
+time.
+
+SBCL has retained some extensions from its parent CMU CL. Many of the

 retained extensions are in these categories:
 .TP 3
 \--
 retained extensions are in these categories:
 .TP 3
 \--

-things which might be in the new ANSI spec, e.g. weak pointers,
-finalization, foreign function interface to C, and Gray streams
+things which might be in the new ANSI spec, \fIe.g.\fR safe type
+declarations, weak pointers, finalization, foreign function
+interface to C, and Gray streams;

 .TP 3
 \--
 things which are universally available in Unix scripting languages,
 .TP 3
 \--
 things which are universally available in Unix scripting languages,

-e.g. RUN-PROGRAM and POSIX argv and getenv
+\fIe.g.\fR \f(CRRUN\-PROGRAM\fR and POSIX \f(CRargv\fR and \f(CRgetenv\fR;

 .TP 3
 \--
 hooks into the low level workings of the system which can be useful
 .TP 3
 \--
 hooks into the low level workings of the system which can be useful

-for debugging, e.g. a list of functions to be run whenever GC occurs,
-or parameters to modify compiler diagnostic output
+for debugging, \fIe.g.\fR requesting that a particular function be executed
+whenever GC occurs, or tuning compiler diagnostic output;

 .TP 3
 \--
 .TP 3
 \--

-unportable performance hacks, e.g. TRULY-THE, FREEZE-TYPE, and PURIFY
+unportable performance hacks, \fIe.g.\fR \f(CRFREEZE\-TYPE\fR and
+\f(CRPURIFY\fR. For more information about these, look at the online
+documentation for symbols in the \f(CRSB\-EXT\fR package, and look at the user
+manual.

 .PP
 
 .PP
 

-There are also a few retained extensions which don't fall into
-any particular category, e.g.
-.TP 3
-\--
-the ability to save running Lisp images as executable files
-.PP
+There are also a few retained extensions which don't fall into any
+particular category, \fIe.g.\fR the ability to save running Lisp images as
+executable files.

 
 Some of the retained extensions have new names and/or different
 options than their CMU CL counterparts. For example, the SBCL function
 
 Some of the retained extensions have new names and/or different
 options than their CMU CL counterparts. For example, the SBCL function

-which saves a Lisp image to disk and kills it is called
-SAVE-LISP-AND-DIE instead of SAVE-LISP, and it supports fewer keyword
-options than CMU CL's SAVE-LISP.
-
-(Why doesn't SBCL support more extensions? Why the hell did I (WHN)
-drop all those nice extensions from CMU CL when the code already
-exists? This is a frequently asked question on the mailing list. The
-answer is that they're hard to maintain, and I have enough on my hands
-already. Also, in the case of some big and unquestionably useful
-extensions, like sockets and Motif, I think that SBCL has done its job
-by supplying the FFI, and that people who need, and understand, and
-are motivated to maintain the functionality should supply it as a
-separate library, which I'd be happy to distribute or link to on the
-SBCL home page. Finally, in the case of multithreading, I do think it
-belongs in the new ANSI spec, and it'd be a good feature to have, but
-I didn't think the CMU CL implementation was sufficiently mature, and
-it's such a complicated and far-reaching extension that I thought that
-trying to fix it would interfere with the more urgent task of getting
-basic ANSI support up to speed.)
+which saves a Lisp image to disk and kills the running process is
+called \f(CRSAVE\-LISP\-AND\-DIE\fR instead of \f(CRSAVE\-LISP\fR, and
+SBCL's \f(CRSAVE\-LISP\-AND\-DIE\fR supports fewer keyword options
+than CMU CL's \f(CRSAVE\-LISP\fR does.
+
+(Why doesn't SBCL support more extensions natively?  Why drop all
+those nice extensions from CMU CL when the code already exists? This
+is a frequently asked question on the mailing list.  There are two
+principal reasons.  First, it's a design philosophy issue: arguably
+SBCL has done its job by supplying a stable FFI, and the right design
+decision is to move functionality derived from that, like socket
+support, into separate libraries.  Some of these are distributed with
+SBCL as "contrib" modules, others are distributed as separate software
+packages by separate maintainers. Second, it's a practical decision -
+focusing on a smaller number of things will, we hope, let us do a
+better job on them.)

 
 .SH THE COMPILER
 
 
 .SH THE COMPILER
 

-SBCL inherits from CMU CL the "Python" native code compiler. This
-compiler is very clever about understanding the type system of Common
-Lisp and using it to produce efficient code, and about producing notes
-to let the user know when the compiler doesn't have enough type
-information to produce efficient code. It also tries (almost always
-successfully) to follow the unusual but very useful principle that
+SBCL inherits from CMU CL the "Python" native code compiler. (Though
+we often avoid that name in order to avoid confusion with the
+scripting language also called Python.) This compiler is very clever
+about understanding the type system of Common Lisp and using it to
+optimize code, and about producing notes to let the user know when the
+compiler doesn't have enough type information to produce efficient
+code. It also tries (almost always successfully) to follow the unusual
+but very useful principle that "declarations are assertions", \fIi.e.\fR

 type declarations should be checked at runtime unless the user
 explicitly tells the system that speed is more important than safety.
 
 type declarations should be checked at runtime unless the user
 explicitly tells the system that speed is more important than safety.
 

-The CMU CL version of this compiler reportedly produces pretty good
-code for modern machines which have lots of registers, but its code
-for the X86 is marred by a lot of extra loads and stores to
-stack-based temporary variables. Because of this, and because of the
-extra levels of indirection in Common Lisp relative to C, we find a
-typical performance decrease by a factor of perhaps 2 to 5 for small
-programs coded in SBCL instead of GCC.
+The compiled code uses garbage collection to automatically
+manage memory. The garbage collector implementation varies considerably
+from CPU to CPU. In particular, on some CPUs the GC is nearly exact,
+while on others it's more conservative, and on some CPUs the GC
+is generational, while on others simpler stop and copy strategies
+are used.

 
 For more information about the compiler, see the user manual.
 
 
 For more information about the compiler, see the user manual.
 

-.SH DOCUMENTATION
-
-Currently, the documentation for the system is
-.TP 3
-\--
-the user manual
-.TP 3
-\--
-this man page
-.TP 3
-\--
-doc strings and online help built into the SBCL executable
-.PP
+.SH COMMAND LINE SYNTAX

 
 

-.SH SYSTEM REQUIREMENTS
+Command line syntax can be considered an advanced topic; for ordinary
+interactive use, no command line arguments should be necessary.

 
 

-Unlike its distinguished ancestor CMU CL, SBCL is currently on X86
-(Linux, FreeBSD, and OpenBSD) and Alpha (Linux). It would probably be
-straightforward to port the CMU CL support for SPARC, or to port to
-NetBSD.
+In order to understand the command line argument syntax for SBCL, it
+is helpful to understand that the SBCL system is implemented as two
+components, a low-level runtime environment written in C and a
+higher-level system written in Common Lisp itself. Some command line
+arguments are processed during the initialization of the low-level
+runtime environment, some command line arguments are processed during
+the initialization of the Common Lisp system, and any remaining
+command line arguments are passed on to user code.

 
 

-As of version 0.6.11, SBCL requires on the order of 16Mb to run. In
-some future version, this number could shrink significantly, since
-large parts of the system are far from execution bottlenecks and could
-reasonably be stored in compact byte compiled form. (CMU CL does this
-routinely; the only reason SBCL doesn't currently do this is a
-combination of bootstrapping technicalities and inertia.)
+The full, unambiguous syntax for invoking SBCL at the command line is
+.TP 3
+.B sbcl [runtime options] \-\-end\-runtime\-options [toplevel options] \-\-end\-toplevel\-options [user options]
+.PP

 
 

-.SH ENVIRONMENT
+For convenience, the \-\-end\-runtime\-options and \-\-end\-toplevel\-options
+elements can be omitted. Omitting these elements can be convenient
+when you are running the program interactively, and you can see that
+no ambiguities are possible with the option values you are using.
+Omitting these elements is probably a bad idea for any batch file
+where any of the options are under user control, since it makes it
+impossible for SBCL to detect erroneous command line input, so that
+erroneous command line arguments will be passed on to the user program
+even if they was intended for the runtime system or the Lisp system.

 
 

-.TP 10n
-.BR SBCL_HOME
-If this variable is set, it overrides the default directories for
-files like "sbclrc" and "sbcl.core", so that instead of being searched
-for in e.g. /etc/, /usr/local/etc/, /usr/lib/, and /usr/local/lib/, they
-are searched for only in the directory named by SBCL_HOME. This is
-intended to support users who wish to use their own version of SBCL
-instead of the version which is currently installed as the system
-default.
+Supported runtime options are
+.TP 3
+.B \-\-core <corefilename>
+Run the specified Lisp core file instead of the default. (See the FILES
+section for the standard core, or the system documentation for
+\f(CRSB\-EXT:SAVE\-LISP\-AND\-DIE\fR for information about how to create a 
+custom core.) Note that if the Lisp core file is a user-created core
+file, it may run a nonstandard toplevel which does not recognize the
+standard toplevel options.
+.TP 3
+.B \-\-dynamic-space-size <megabytes>
+Size of the dynamic space reserved on startup in megabytes. Default value
+is platform dependent.
+.TP 3
+.B \-\-noinform
+Suppress the printing of any banner or other informational message at
+startup. (This makes it easier to write Lisp programs which work
+cleanly in Unix pipelines. See also the "\-\-noprint" and
+"\-\-disable\-debugger" options.)
+.TP 3
+.B \-\-help
+Print some basic information about SBCL, then exit.
+.TP 3
+.B \-\-version
+Print SBCL's version information, then exit.

 .PP
 
 .PP
 

-.SH FILES
+In the future, runtime options may be added to control behavior such
+as lazy allocation of memory.

 
 

-/usr/lib/sbcl.core and /usr/local/lib/sbcl.core are the standard
-locations for the standard SBCL core, unless overridden by the SBCL_HOME
-variable.
+Runtime options, including any \-\-end\-runtime\-options option,
+are stripped out of the command line before the
+Lisp toplevel logic gets a chance to see it.

 
 

-/etc/sbclrc and /usr/local/etc/sbclrc are the standard locations for
-system-wide SBCL initialization files, unless overridden by the
-SBCL_HOME variable or the --sysinit command line option.
+The toplevel options supported by the standard SBCL core are
+.TP 3
+.B \-\-sysinit <filename>
+Load filename instead of the default system-wide initialization file.
+(See the FILES section.)
+.TP 3
+.B \-\-no\-sysinit
+Do not load a system-wide initialization file. If this option is
+given, the \-\-sysinit option is ignored.
+.TP 3
+.B \-\-userinit <filename>
+Load filename instead of the default user initialization file. (See
+the FILES section.)
+.TP 3
+.B \-\-no\-userinit
+Do not load a user initialization file. If this option is
+given, the \-\-userinit option is ignored.
+.TP 3
+.B \-\-eval <command>
+After executing any initialization file, but before starting the
+read-eval-print loop on standard input, read and evaluate the command
+given. More than one \-\-eval option can be used, and all will be read
+and executed, in the order they appear on the command line.
+.TP 3
+.B \-\-load <filename>
+This is equivalent to \-\-eval \(aq(load "<filename>")\(aq. The special
+syntax is intended to reduce quoting headaches when invoking SBCL
+from shell scripts.
+.TP 3
+.B \-\-noprint
+When ordinarily the toplevel "read-eval-print loop" would be executed,
+execute a "read-eval loop" instead, \fIi.e.\fR don't print a prompt and
+don't echo results. Combined with the \-\-noinform runtime option, this
+makes it easier to write Lisp "scripts" which work cleanly in Unix
+pipelines.
+.TP 3
+.B \-\-disable\-debugger
+This is equivalent to \-\-eval \(aq(sb\-ext:disable\-debugger)\(aq. By
+default, a Common Lisp system tries to ask the programmer for help
+when it gets in trouble (by printing a debug prompt, then listening,
+on \f(CR*DEBUG\-IO*\fR). However, this is not useful behavior for a system
+running with no programmer available, and this option tries to set up
+more appropriate behavior for that situation. This is implemented by
+redefining \f(CRINVOKE\-DEBUGGER\fR so that any call exits the process with a
+failure code after printing a backtrace. (Note that because it is
+implemented by modifying special variables and \f(CRFDEFINITION\fRs, its
+effects persist in .core files created by
+\f(CRSB\-EXT:SAVE\-LISP\-AND\-DIE\fR.  If you want to undo its
+effects, \fIe.g.\fR if you build a system unattended and then want to
+operate a derived system interactively, see the
+\f(CRSB\-EXT:ENABLE\-DEBUGGER\fR command.)
+.PP

 
 

+Regardless of the order in which \-\-sysinit, \-\-userinit, and
+\-\-eval options appear on the command line, the sysinit file, if it
+exists, is loaded first; then the userinit file, if it exists, is
+loaded; then any \-\-eval commands are read and executed in sequence;
+then the read-eval-print loop is started on standard input. At any
+step, error conditions or commands such as \f(CRSB\-EXT:QUIT\fR can
+cause execution to be terminated before proceeding to subsequent
+steps.
+
+Note that when running SBCL with the \-\-core option, using a core
+file created by a user call to the
+\f(CRSB\-EXT:SAVE\-LISP\-AND\-DIE\fR, the toplevel options may be
+under the control of user code passed as arguments to
+\f(CRSB\-EXT:SAVE\-LISP\-AND\-DIE\fR. For this purpose, the
+\-\-end\-toplevel\-options option itself can be considered a toplevel
+option, \fIi.e.\fR the user core, at its option, may not support it.
+
+In the standard SBCL startup sequence (\fIi.e.\fR with no user core
+involved) toplevel options and any \-\-end\-toplevel\-options option are
+stripped out of the command line argument list before user code gets a
+chance to see it.

 
 

-$HOME/.sbclrc is the standard location for a user's SBCL
-initialization file, unless overridden by the --userinit
-command line option.
+.SH SYSTEM REQUIREMENTS

 
 

-.SH BUGS
+SBCL currently runs on X86 (Linux, FreeBSD, OpenBSD, and NetBSD),
+X86-64 (Linux), Alpha (Linux, Tru64), PPC (Linux, Darwin/MacOS X),
+SPARC (Linux and Solaris 2.x), and MIPS (Linux).  For information on
+other ongoing and possible ports, see the sbcl\-devel mailing list,
+and/or the web site.

 
 

-To report a bug, please send mail to sbcl-help@lists.sourceforge.net
-or sbcl-devel@lists.sourceforge.net. As with any software bug report,
-it's most helpful if you remember to describe the environment where
-the problem occurs (machine type, O/S name and version, etc.) and if
-you can provide enough information to reproduce the problem,
-preferably in compact form.
+SBCL requires on the order of 16Mb RAM to run on X86 systems, though
+all but the smallest programs would be happier with 32Mb or more.

 
 

-This section attempts to list the most serious and long-standing bugs
-or surprising performance hits. For more detailed and current
-information on bugs, see the BUGS file in the distribution.
+.SH KNOWN BUGS

 
 

-It is possible to get in deep trouble by exhausting
-memory. To plagiarize a sadly apt description of a language not
-renowned for the production of bulletproof software, "[The current
-SBCL implementation of] Common Lisp makes it harder for you to shoot
-yourself in the foot, but when you do, the entire universe explodes."
-.TP 3
-\--
-The system doesn't deal well with stack overflow. (It tends to cause
-a segmentation fault instead of being caught cleanly.)
-.TP 3
-\--
-Like CMU CL, the SBCL system overcommits memory at startup. On typical
-Unix-alikes like Linux and FreeBSD, this means that if the SBCL system
-turns out to use more virtual memory than the system has available for
-it, other processes tend to be killed randomly (!).
-.PP
+This section attempts to list the most serious and long-standing bugs.
+For more detailed and current information on bugs, see the BUGS file
+in the distribution.

 
 

-The compiler is overaggressive about static typing, assuming that a
-function's return type never changes. Thus compiling and loading a
-file containing
-(DEFUN FOO (X) NIL)
-(DEFUN BAR (X) (IF (FOO X) 1 2))
-(DEFUN FOO (X) (PLUSP X))
-then running (FOO 1) gives 2 (because the compiler "knew"
-that FOO's return type is NULL).
+It is possible to get in deep trouble by exhausting heap memory.  The
+SBCL system overcommits memory at startup, so, on typical Unix-alikes
+like Linux and FreeBSD, this means that if the SBCL system turns out
+to use more virtual memory than the system has available for it, other
+processes tend to be killed randomly (!).

 
 The compiler's handling of function return values unnecessarily
 violates the "declarations are assertions" principle that it otherwise
 
 The compiler's handling of function return values unnecessarily
 violates the "declarations are assertions" principle that it otherwise

-adheres to. Using PROCLAIM or DECLAIM to specify the return type of a
-function causes the compiler to believe you without checking. Thus
-compiling a file containing
-(DECLAIM (FTYPE (FUNCTION (T) NULL) SOMETIMES))
-(DEFUN SOMETIMES (X) (ODDP X))
-(DEFUN FOO (X) (IF (SOMETIMES X) 'THIS-TIME 'NOT-THIS-TIME))
-then running (FOO 1) gives NOT-THIS-TIME, because the
-never compiled code to check the declaration.
-
-The implementation of multidimensional arrays, especially
-multidimensional arrays of floating point numbers, is very
-inefficient.
-
-SYMBOL-FUNCTION is much slower than you might expect, being
-implemented not as a slot access but as a search through the
-compiler/kernel "globaldb" database.
-
-CLOS (based on the PCL reference implementation) is somewhat
-inefficient.
-
-There are many nagging pre-ANSIisms, e.g.
+adheres to. Using \f(CRPROCLAIM\fR or \f(CRDECLAIM\fR to specify the
+return type of a function causes the compiler to believe you without
+checking. Thus compiling a file containing
+\f(CR
+  (DECLAIM (FTYPE (FUNCTION (T) NULL) SOMETIMES))
+  (DEFUN SOMETIMES (X) (ODDP X))
+  (DEFUN FOO (X) (IF (SOMETIMES X) \(aqTHIS\-TIME \(aqNOT\-THIS\-TIME))\fR
+.br
+then running \f(CR(FOO 1)\fR gives \f(CRNOT\-THIS\-TIME\fR, because
+the compiler relied on the truth of the \f(CRDECLAIM\fR without checking it.
+
+Some things are implemented very inefficiently.

 .TP 3
 \--
 .TP 3
 \--

-CLOS (based on the PCL reference implementation) is incompletely
-integrated into the system, so that e.g. SB-PCL::FIND-CLASS is a
-different function than CL::FIND-CLASS. (This is less of a problem in
-practice than the speed, but it's still distasteful.)
-.TP 3
---
-The ANSI-recommended idiom for creating a function which is only
-sometimes expanded inline,
-(DECLAIM (INLINE F))
-(DEFUN F ...)
-(DECLAIM (NOTINLINE F)),
-doesn't do what you'd expect. (Instead, you have to declare the
-function as SB-EXT:MAYBE-INLINE to get the desired effect.)
+Multidimensional arrays are inefficient, especially
+multidimensional arrays of floating point numbers.

 .TP 3
 \--
 .TP 3
 \--

-The DYNAMIC-EXTENT declaration is not implemented, and is simply
-ignored. (This is allowed by the ANSI spec, but can have a large
-efficiency cost in some kinds of code, e.g. code which uses a lot
-of upward closures or &REST lists.)
-.TP 3
---
-Compiling DEFSTRUCT in strange places (e.g. inside a DEFUN) doesn't
-do anything like what it should.
+CLOS isn't particularly efficient. (In part, CLOS is so dynamic
+that it's slow for fundamental reasons, but beyond that, the
+SBCL implementation of CLOS doesn't do some important known
+optimizations.)

 .TP 3
 \--
 .TP 3
 \--

-The symbol * is the name of a type similar to T. (It's used as part of
-the implementation of compound types like (ARRAY * 1) and (CONS * *).
-In a strict ANSI implementation, * would not be the name of a type,
-but instead just a symbol which is recognized and handled specially by
-certain type expanders.)
+SBCL, like most (maybe all?) implementations of Common Lisp on stock
+hardware, has trouble passing floating point numbers around
+efficiently, because a floating point number, plus a few extra bits to
+identify its type, is larger than a machine word. (Thus, they get
+"boxed" in heap-allocated storage, causing GC overhead.) Within a
+single compilation unit, or when doing built-in operations like
+\f(CRSQRT\fR and \f(CRAREF\fR, or some special operations like
+structure slot accesses, this is avoidable: see the user manual for
+some efficiency hints. But for general function calls across the
+boundaries of compilation units, passing the result of a floating
+point calculation as a function argument (or returning a floating
+point result as a function value) is a fundamentally slow operation.

 .PP
 
 .PP
 

+.SH REPORTING BUGS
+
+To report a bug, please send mail to the mailing lists sbcl-help or
+sbcl-devel. You can find the complete mailing list addresses on the
+web pages at <\f(CRhttp://sbcl.sourceforge.net/\fR>; note that as a
+spam reduction measure you must subscribe to the lists before you can
+post. (You may also find fancy SourceForge bug-tracking machinery
+there, but don't be fooled. As of 2002-07-25 anyway, we don't actively
+monitor that machinery, and it exists only because we haven't been
+able to figure out how to turn it off.)
+
+As with any software bug report, it's most helpful if you can provide
+enough information to reproduce the symptoms reliably, and if you say
+clearly what the symptoms are.  For example, "There seems to be
+something wrong with TAN of very small negative arguments. When I
+execute \f(CR(TAN LEAST\-NEGATIVE\-SINGLE\-FLOAT)\fR interactively on
+sbcl-1.2.3 on my Linux 4.5 X86 box, I get an \f(CRUNBOUND\-VARIABLE\fR
+error."
+

 .SH SUPPORT
 
 Various information about SBCL is available at
 .SH SUPPORT
 
 Various information about SBCL is available at

-<http://sbcl.sourceforge.net/>. The mailing lists there are the
-recommended place to look for support.
+<\f(CRhttp://www.sbcl.org/\fR>. The mailing lists there are the recommended
+place to look for support.

 
 

-.SH DISTRIBUTION
+.SH ENVIRONMENT
+
+.TP 10n
+.BR SBCL_HOME
+This variable controls where files like "sbclrc", "sbcl.core", and the
+add-on "contrib" systems are searched for.  If it is not set, then
+sbcl sets it from a compile-time default location which is usually
+/usr/local/lib/sbcl/ but may have been changed \fIe.g.\fR by a third-party
+packager.

 
 

-SBCL is a free implementation of Common Lisp derived from CMU CL. Both
-sources and executables are freely available; this software is "as
-is", and has no warranty of any kind. CMU and the authors assume no
-responsibility for the consequences of any use of this software. See
-the CREDITS file in the distribution for more information about
-history, contributors and permissions.
+.SH FILES

 
 

+.TP
+.I sbcl
+executable program containing some low-level runtime support and
+a loader, used to read sbcl.core
+.TP
+.I sbcl.core
+dumped memory image containing most of SBCL, to be loaded by
+the `sbcl' executable.  Looked for in $\f(CRSBCL_HOME\fR,
+unless overridden by the \f(CR\-\-core\fR option.
+.TP
+.I sbclrc
+optional system-wide startup script, looked for in $\f(CRSBCL_HOME\fR/sbclrc
+then /etc/sbclrc, unless overridden by the \f(CR\-\-sysinit\fR command line
+option.
+.TP
+.I .sbclrc
+optional per-user customizable startup script (in user's home
+directory, or as specified by  \f(CR\-\-userinit\fR)
+
+.SH AUTHORS
+
+Dozens of people have made substantial contributions to SBCL and its
+subsystems, and to the CMU CL system on which it was based, over the
+years. See the CREDITS file in the distribution for more information.
+
+.SH SEE ALSO
+
+Full SBCL documentation is maintained as a Texinfo manual. If is has
+been installed, the command
+.IP
+.B info sbcl
+.PP
+should give you access to the complete manual. Depending on your
+installation it may also be available in HTML and PDF formats in eg.
+.IP
+.B /usr/local/share/doc/sbcl/
+.PP
+See the SBCL homepage 
+.IP
+.B <\f(CRhttp://www.sbcl.org/\fR>
+.PP
+for more information, including directions on how to subscribe to the
+sbcl\-devel and sbcl\-help mailing-lists.