.TH SBCL 1 "$Date$"
.AT 3
.SH NAME
-SBCL -- "Steel Bank Common Lisp"
+SBCL -- Steel Bank Common Lisp
.SH DESCRIPTION
-SBCL is a free Common Lisp programming environment. It is derived from
-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.)
-
-.SH LICENSING
+SBCL is an implementation of ANSI Common Lisp, featuring a
+high-performance native compiler, native threads on several platforms,
+a socket interface, a source-level debugger, a statistical profiler,
+and much more.
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.
+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.
For more information about license issues, see the COPYING file in
the distribution. For more information about history, see the
.SH RUNNING SBCL
-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 ("*"). 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. E.g.
+To run SBCL, type "sbcl". After startup messages a prompt
+("\f(CR*\fR") appears. Enter a Lisp expression, and SBCL will read and
+execute it, print any values returned, give you another prompt, and
+wait for your next input.
+\f(CR
+ $ sbcl
+ ...[startup messages elided]...
* (+ 1 2 3)
6
- * (funcall (lambda (x y) (list x y y)) :toy :choo)
-
- (:TOY :CHOO :CHOO)
- * "Hello World"
-
- "Hello World"
- *
-
-Many people like to run SBCL, like other Lisp systems, as a subprocess
-under Emacs. The Emacs "ilisp" mode provides many convenient features,
-like command line editing, tab completion, and various kinds of
-coupling between Common Lisp source files and the interactive SBCL
-subprocess.
-
-.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 yet reached 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.
-
-Many Lispy extensions have been retained from CMU CL:
-.TP 3
-\--
-CMU-CL-style safe implementation of type declarations:
-"Declarations are assertions."
-.TP 3
-\--
-the source level debugger (very similar to CMU CL's)
-.TP 3
-\--
-the profiler (now somewhat different from CMU CL's)
-.TP 3
-\--
-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
-\--
-weak pointers and finalization (which have unfortunately
-suffered from at least some code rot, so that e.g. weak hash
-tables don't work)
-.PP
-
-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, e.g. reading POSIX argc and argv, 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
-the version of the source code that it was created from. This clean
-bootstrappability was the immediate motivation for forking off of the
-CMU CL development tree. A variety of implementation differences are
-motivated by this design goal.
+ * (exit)
+\fR
-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 people like to run SBCL as a subprocess under Emacs. The Emacs
+"Slime" mode provides many convenient features, like command line
+editing, tab completion, and various kinds of coupling between Common
+Lisp source files and the interactive SBCL subprocess.
-Most extensions supported by CMU CL are not supported in SBCL,
-including Motif support, the Hemlock editor, search paths, the
-low-level Unix interface, the WIRE protocol, multithreading, various
-user-level macros and functions (e.g. LETF, ITERATE, MEMQ,
-REQUIRED-ARGUMENT), and many others.
-
-SBCL has retained some extensions from parent CMU CL. Many of the
-retained extensions are in these categories:
-.TP 3
-\--
-things which might be in the new ANSI spec, e.g. 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,
-e.g. RUN-PROGRAM and POSIX argv and getenv
-.TP 3
-\--
-hooks into the low level workings of the system which can be useful
-for debugging, e.g. requesting that a particular function be executed
-whenever GC occurs, or tuning compiler diagnostic output
-.TP 3
-\--
-unportable performance hacks, e.g. FREEZE-TYPE and PURIFY. For more
-information about these, look at the online documentation for symbols
-in the SB-EXT package, and look at the user manual.
-.PP
-
-There are also a few retained extensions which don't fall into any
-particular category, e.g. 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
-which saves a Lisp image to disk and kills the running process is
-called SAVE-LISP-AND-DIE instead of SAVE-LISP, and SBCL's
-SAVE-LISP-AND-DIE supports fewer keyword options than CMU CL's
-SAVE-LISP does.
-
-(Why doesn't SBCL support more extensions? Why drop all those nice
-extensions from CMU CL when the code already exists? This is a
-frequently asked question on the mailing list. In some cases, 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,
-distributed as separate software packages by separate maintainers. In
-other cases it's a practical decision, hoping that focusing on a
-smaller number of things will let us do a better job on them. This is
-very much the case for multithreading: it's an important, valuable
-extension, but it's not easy to get right, and especially while SBCL
-is still working on basic ANSI compliance, difficult extensions aren't
-likely to be a priority.)
-
-.SH THE COMPILER
-
-SBCL is essentially a compiler-only implementation of Lisp. All
-nontrivial Lisp code is compiled to native machine code before being
-executed, even when the Lisp code is typed interactively at the
-"interpreter" prompt.
-
-SBCL inherits from CMU CL the "Python" native code compiler. (Though
-we've essentially dropped 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", i.e.
-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 CPU architectures 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, the
-performance of SBCL isn't going to impress people who are impressed by
-small constant factors. However, even on the X86 it tends to be faster
-than byte interpreted languages (and can be a lot faster).
-
-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.
-
-.SH DOCUMENTATION
-
-Currently, the documentation for the system is
-.TP 3
-\--
-this man page
-.TP 3
-\--
-the user manual
-.TP 3
-\--
-doc strings and online help built into the SBCL executable
-.PP
+For information on creating "standalone executables" using SBCL, see
+\f(CRSB\-EXT:SAVE\-LISP\-AND\-DIE\fR in the User Manual.
.SH COMMAND LINE SYNTAX
-Command line syntax can be considered an advanced topic; for ordinary
-interactive use, no command line arguments should be necessary.
+For ordinary interactive use, no command line arguments should be
+necessary.
-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
+In order to understand the SBCL command line syntax, it is helpful to
+understand that the system is composed of two parts: a runtime
+environment, and the Common Lisp system it supports. Some command line
+arguments are processed during the initialization of the runtime, and
+some during the initialization of the Lisp system -- any remaining
command line arguments are passed on to user code.
-The full, unambiguous syntax for invoking SBCL at the command line is
+The overall command line syntax is:
.TP 3
-.B sbcl [runtime options] --end-runtime-options [toplevel options] --end-toplevel-options [user options]
+.B sbcl [runtime options] \-\-end\-runtime\-options [toplevel options] \-\-end\-toplevel\-options [user options]
.PP
-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.
+Both \-\-end\-runtime\-options and \-\-end\-toplevel\-options are
+optional, and may be omitted. They are intended for use in situations
+where any command line options are under user control (e.g. in batch
+files): by using them you can prevent options intended for your
+program being accidentally processed by SBCL.
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.
+.B \-\-core <corefilename>
+Use 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 \-\-control-stack-size <megabytes>
+Size of control stack reserved for each thread in megabytes. Default value
+is 2.
.TP 3
-.B --noinform
+.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.)
+cleanly in Unix pipelines. See also the "\-\-noprint" and
+"\-\-disable\-debugger" options.)
+.TP 3
+.B \-\-disable\-ldb
+Disable the low-level debugger. Only effective if SBCL is compiled with LDB.
+.TP 3
+.B \-\-lose\-on\-corruption
+There are some dangerous low level errors (for instance, control stack
+exhausted, memory fault) that (or whose handlers) can corrupt the
+image. By default SBCL prints a warning, then tries to continue and
+handle the error in Lisp, but this will not always work and SBCL may
+malfunction or even hang. With this option, upon encountering such an
+error SBCL will invoke ldb (if present and enabled) or else exit.
+.TP 3
+.B \-\-script <filename>
+As a runtime option equivalent to \-\-noinform \-\-disable\-ldb
+\-\-lose\-on\-corruption \-\-end\-runtime\-options \-\-script
+<filename>. See the description of \-\-script as a toplevel option
+below.
+.TP 3
+.B \-\-merge\-core\-pages
+When platform support is present, provide hints to the operating
+system that identical pages may be shared between processes until they
+are written to. This can be useful to reduce the memory usage on
+systems with multiple SBCL processes started from similar but
+differently\-named core files, or from compressed cores. Without
+platform support, do nothing.
+.TP 3
+.B \-\-no-merge\-core\-pages
+Ensures that no sharing hint is provided to the operating system.
+.TP 3
+.B \-\-default\-merge\-core\-pages
+Reverts the sharing hint policy to the default: only compressed cores
+trigger hinting. Uncompressed cores are mapped directly from the core
+file, which is usually enough to ensure sharing.
+.TP 3
+.B \-\-help
+Print some basic information about SBCL, then exit.
+.TP 3
+.B \-\-version
+Print SBCL's version information, then exit.
.PP
In the future, runtime options may be added to control behavior such
as lazy allocation of memory.
-Runtime options, including any --end-runtime-options option,
+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.
-Supported toplevel options for the standard SBCL core are
+The toplevel options supported by the standard SBCL core are
.TP 3
-.B --sysinit <filename>
+.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.
+(See the FILES section.)
.TP 3
-.B --userinit <filename>
+.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.) 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 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>
+.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.
+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 '(load "<filename>")'. The special
+.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
+.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
+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 '(sb-ext:disable-debugger)'.
-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. This is implemented by modifying special
-variables: 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. Because it is implemented by modifying special variables,
-its effects persist in .core files created by SB-EXT:SAVE-LISP-AND-DIE.
-(If you want to undo its effects, see the SB-EXT:ENABLE-DEBUGGER
-command.)
+.B \-\-disable\-debugger
+By default when SBCL encounters an error, it enters the builtin
+debugger, allowing interactive diagnosis and possible intercession.
+This option disables the debugger, causing errors to print a backtrace
+and exit with status 1 instead -- which is a mode of operation better suited
+for batch processing. See the User Manual on \f(CRSB\-EXT:DISABLE\-DEBUGGER\fR for details.
+.TP 3
+.B \-\-quit
+At the end of toplevel option processing, exit SBCL with a successful
+code of zero. Note that the effect of this option is delayed until after
+toplevel options following this one.
+.TP 3
+.B \-\-non-interactive
+This option disables the read-eval-print loop for both exceptional and
+non-exceptional reasons. It is short for --disable-debugger and --quit in
+combination and is useful for batch uses where the special option processing
+implied by --script is not desired.
+.TP 3
+.B \-\-script <filename>
+Implies \-\-no-sysinit \-\-no-userinit \-\-disable-debugger
+\-\-end\-toplevel\-options.
+
+Causes the system to load the specified file and exit immediately
+afterwards, instead of entering the read-eval-print loop. If the file
+begins with a shebang line, it is ignored.
.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
+Regardless of the order in which toplevel options appear on the command
+line, the order of actions is:
+
+.nr step 1 1
+.IP \n[step]. 3
+Debugger is disabled, if requested.
+.IP \n+[step].
+Any system initialization file is loaded, unless prohibited.
+.IP \n+[step].
+Any user initialization file is loaded, unless prohibited.
+.IP \n+[step].
+\-\-eval and \-\-load options are processed in the order given.
+.PP
+
+Finally, either the read-eval-print loop is entered or the file
+specified with \-\-script option is loaded.
+
+When running in the read-eval-print loop the system exits on end of
+file. Similarly, the system exits immediately after processing the
+file specified with \-\-script.
+
+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.
-.SH SYSTEM REQUIREMENTS
+.SH OVERVIEW
-SBCL currently runs on
-X86 (Linux, FreeBSD, and OpenBSD), Alpha (Linux, Tru64), PPC
-(Linux) and SPARC (Linux and Solaris 2.x).
-For information on other ongoing and possible ports, see the
-sbcl-devel mailing list, and/or the web site.
+SBCL is derived from the CMU CL. (The name is intended to acknowledge
+the connection: steel and banking are the industries where Carnegie
+and Mellon made the big bucks.)
-SBCL requires on the order of 16Mb RAM to run on X86 systems,
-though for all but the smallest programs would be happier with 32Mb
-or more.
+SBCL compiles by default: even functions entered in the
+read-eval-print loop are compiled to native code, unless the evaluator
+has been explicitly turned on. (Even today, some 30 years after the
+MacLisp compiler, people will tell you that Lisp is an interpreted
+language. Ignore them.)
-.SH ENVIRONMENT
+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.
-.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.
+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
+
+For more information, see the User Manual.
.PP
-.SH FILES
+.SH THE COMPILER
-/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.
+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.
+
+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.
+
+.SH SYSTEM REQUIREMENTS
-/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.
+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.
-$HOME/.sbclrc is the standard location for a user's SBCL
-initialization file, unless overridden by the --userinit
-command line option.
+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.
.SH KNOWN BUGS
For more detailed and current information on bugs, see the BUGS file
in the distribution.
-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
-\--
-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
+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
-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.
+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
multidimensional arrays of floating point numbers.
.TP 3
\--
-The DYNAMIC-EXTENT declaration isn't implemented at all, not even
-for &REST lists or upward closures, so such constructs always allocate
-their temporary storage from the heap, causing GC overhead.
-.TP 3
-\--
-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
-\--
-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 SQRT and AREF,
-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
-
-There are still some nagging pre-ANSIisms, notably
-.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. (In practice, you need to
-be a pretty advanced user before this is a serious problem, and
-by then you can usually work around it, but it's still distasteful.
-It's arguably the outstanding "This should be fixed by version 1.0"
-issue.)
-.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.)
-.TP 3
-\--
-There are several nonconforming bits of type syntax. E.g. (1) The type
-FOO is strictly equivalent to (FOO), so e.g. the type OR is treated as
-the type (OR), i.e. the empty type. This is the way that the ancestral
-code worked, and even though ANSI specifically forbids it, it hasn't
-been fixed yet. (2) 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
.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, <http://sbcl.sourceforge.net/>. (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.)
+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. E.g. "There seems to be something wrong
-with TAN of very small negative arguments. When I execute
-(TAN LEAST-NEGATIVE-SINGLE-FLOAT) interactively on sbcl-1.2.3 on my
-Linux 4.5 X86 box, I get an UNBOUND-VARIABLE error."
+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 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
+bootstrappability was the immediate motivation for forking off of the
+CMU CL development tree. A variety of implementation differences are
+motivated by this design goal.
+
+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 have been unbundled from SBCL,
+including Motif support, the Hemlock editor, search paths, 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.
+
+(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 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 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 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.
.SH FILES
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
+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 (in an etc-ish system
-configuration file directory)
+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)
+optional per-user customizable startup script (in user's home
+directory, or as specified by \f(CR\-\-userinit\fR)
-.SH AUTHORS
+.SH SEE ALSO
-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.
+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 e.g.
+.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.
projects / sbcl.git / blobdiff