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gambit-c.txi
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\input texinfo
@c %**start of header
@setfilename gambit-c.info
@settitle Gambit-C, a portable implementation of Scheme
@finalout
@c %**end of header
@include version.txi
@iftex
@tableindent=1.3in
@end iftex
@ifinfo
@format
START-INFO-DIR-ENTRY
* Gambit-C: (gambit-c). A portable implementation of Scheme.
* gsi: (gambit-c) interpreter. Gambit interpreter.
* gsc: (gambit-c) compiler. Gambit compiler.
END-INFO-DIR-ENTRY
@end format
@end ifinfo
@c Define new indices for commands, file names, and options.
@defcodeindex cm
@defcodeindex fl
@defcodeindex op
@c Put everything in one index (arbitrarily chosen to be the concept index).
@syncodeindex cm cp
@syncodeindex fl cp
@syncodeindex fn cp
@syncodeindex ky cp
@syncodeindex op cp
@syncodeindex pg cp
@syncodeindex vr cp
@ifinfo
This file documents Gambit-C, a portable implementation of Scheme.
Copyright (C) 1994-2009 Marc Feeley.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).
@end ignore
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.
Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation approved
by the copyright holder.
@end ifinfo
@titlepage
@title Gambit-C @value{VERSION}
@subtitle A portable implementation of Scheme
@subtitle Edition @value{EDITION}, @value{UPDATED}
@author Marc Feeley
@page
@vskip 0pt plus 1filll
Copyright @copyright{} 1994-2009 Marc Feeley.
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.
Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation approved
by the copyright holder.
@end titlepage
@ifnottex
@node Top, , (dir), (dir)
@top Gambit-C
@cindex Gambit-C
@cindex Scheme, implementation of
This manual documents Gambit-C. It covers release @value{VERSION}.
@menu
* The Gambit-C system:: The Gambit-C system
* Accessing the system files:: Accessing the system files
* GSI:: The Gambit Scheme interpreter
* GSC:: The Gambit Scheme compiler
* Runtime options:: Runtime options
* Debugging:: Debugging
* Scheme extensions:: Scheme extensions
* Namespaces:: Namespaces
* Characters and strings:: Characters and strings
* Numbers:: Numbers
* Homogeneous vectors:: Homogeneous vectors
* Hashing and weak references:: Hashing and weak references
* Records:: Records
* Threads:: Threads
* Dynamic environment:: Dynamic environment
* Exceptions:: Exceptions
* Host environment:: Host environment
* I/O and ports:: I/O and ports
* Lexical syntax and readtables:: Lexical syntax and readtables
* C-interface:: C-interface
* System limitations:: System limitations
* Copyright and license:: Copyright and license
* General index:: General index
@end menu
@end ifnottex
@node The Gambit-C system, GSI, Top, Top
@chapter The Gambit-C system
@cindex Gambit
@cindex Gambit-C
@cindex Scheme
@pindex gsi
@pindex gsc
The Gambit programming system is a full implementation of the Scheme
language which conforms to the R4RS, R5RS and IEEE Scheme standards. It
consists of two main programs: @code{gsi}, the Gambit Scheme
interpreter, and @code{gsc}, the Gambit Scheme compiler.
Gambit-C is a version of the Gambit programming system in which the
compiler generates portable C code, making the whole Gambit-C system and
the programs compiled with it easily portable to many computer
architectures for which a C compiler is available. With appropriate
declarations in the source code the executable programs generated by
the compiler run roughly as fast as equivalent C programs.
For the most up to date information on Gambit and add-on packages
please check the Gambit web page at
@uref{http://gambit.iro.umontreal.ca}. The web page has links to the
Gambit mailing list, the bug reporting system, and the source code
repository.
@menu
* Accessing the system files:: Accessing the system files
@end menu
@node Accessing the system files, , The Gambit-C system, The Gambit-C system
@section Accessing the system files
Files related to Gambit, such as executables, libraries and header files,
are stored in multiple @dfn{Gambit installation directories}.
Gambit may be installed on a system according to two different
installation models.
In the first model there is a single directory where all the Gambit
installation directories are stored. This @dfn{central installation
directory} is typically @code{/usr/local/Gambit-C} under UNIX,
@code{/Library/Gambit-C} under Mac OS X and @code{C:/Program
Files/Gambit-C} under Microsoft Windows. This may have been
overridden when the system was built with the command @samp{configure
--prefix=/my/Gambit-C}. If the system was built with the command
@samp{configure --enable-multiple-versions} then the central
installation directory is @code{@r{@i{prefix}}/@r{@i{version}}}, where
@code{@r{@i{version}}} is the system version string
(e.g. @code{@value{VERSION}} for Gambit @value{VERSION}). Moreover,
@code{@r{@i{prefix}}/current} will be a symbolic link which points to
the central installation directory. In this model, the Gambit
installation directory named @var{X} is simply the subdirectory
@var{X} of the central installation directory.
In the second model some or all of the Gambit installation directories
are stored in installation specific directories. The location of
these directories is assigned when the system is built using the
command @samp{configure --bindir=/my/bin --includedir=/my/include
--libdir=/my/lib}.
The advantage of the first model is that it is easy to have multiple
versions of Gambit coexist and to remove all the files of a given
version. However, the second model may be necessary to conform to the
package installation conventions of some operating systems.
Executable programs such as the interpreter @code{gsi} and compiler
@code{gsc} can be found in the @code{bin} installation directory.
Adding this directory to the @code{PATH} environment variable allows
these programs to be started by simply entering their name. This is
done automatically by the Mac OS X and Microsoft Windows installers.
The runtime library is located in the @code{lib} installation
directory. When the system's runtime library is built as a
shared-library (with the command @samp{configure --enable-shared}) all
programs built with Gambit-C, including the interpreter and compiler,
need to find this library when they are executed and consequently this
directory must be in the path searched by the system for
shared-libraries. This path is normally specified through an
environment variable which is @code{LD_LIBRARY_PATH} on most versions
of UNIX, @code{LIBPATH} on AIX, @code{SHLIB_PATH} on HPUX,
@code{DYLD_LIBRARY_PATH} on Mac OS X, and @code{PATH} on Microsoft
Windows. If the shell is @code{sh}, the setting of the path can be
made for a single execution by prefixing the program name with the
environment variable assignment, as in:
@smallexample
@b{}$ @b{LD_LIBRARY_PATH=/usr/local/Gambit-C/lib gsi}
@end smallexample
A similar problem exists with the Gambit header file @code{gambit.h},
located in the @code{include} installation directory. This header
file is needed for compiling Scheme programs with the Gambit-C
compiler. When the C compiler is being called explicitly it may be
necessary to use a @code{-I@var{<dir>}} command line option to
indicate where to find header files and a @code{-L@var{<dir>}} command
line option to indicate where to find libraries. Access to both of
these files can be simplified by creating a link to them in the
appropriate system directories (special privileges may however be
required):
@smallexample
@b{}$ @b{ln -s /usr/local/Gambit-C/lib/libgambc.a /usr/lib} @r{@i{# name may vary}}
$ @b{ln -s /usr/local/Gambit-C/include/gambit.h /usr/include}
@end smallexample
This may have been done by the installation process. Alternatively
these files can be copied or linked in the directory where the C
compiler is invoked (this requires no special privileges).
@ifinfo
@menu
* GSI:: The Gambit Scheme interpreter
* GSC:: The Gambit Scheme compiler
* Runtime options:: Runtime options
* Debugging:: Debugging
* Scheme extensions:: Scheme extensions
* Namespaces:: Namespaces
* Characters and strings:: Characters and strings
* Numbers:: Numbers
* Homogeneous vectors:: Homogeneous vectors
* Hashing and weak references:: Hashing and weak references
* Records:: Records
* Threads:: Threads
* Dynamic environment:: Dynamic environment
* Exceptions:: Exceptions
* Host environment:: Host environment
* I/O and ports:: I/O and ports
* Lexical syntax and readtables:: Lexical syntax and readtables
* C-interface:: C-interface
* System limitations:: System limitations
* Copyright and license:: Copyright and license
@end menu
@end ifinfo
@node GSI, GSC, The Gambit-C system, Top
@chapter The Gambit Scheme interpreter
@cindex interpreter
Synopsis:
@example
@b{}gsi @r{[}-:@r{@var{runtimeoption}},@dots{}@r{]} @r{[}-i@r{]} @r{[}-f@r{]} @r{[}-v@r{]} @r{[}@r{[}-@r{]} @r{[}-e @r{@var{expressions}}@r{]} @r{[}@r{@var{file}}@r{]}@r{]}@dots{}
@end example
@pindex gsi
The interpreter is executed in @dfn{interactive mode} when no file or
@samp{-} or @samp{-e} option is given on the command line. Otherwise
the interpreter is executed in @dfn{batch mode}. The @samp{-i} option
is ignored by the interpreter. The initialization file will be
examined unless the @samp{-f} option is present (@pxref{GSI
customization}). The @samp{-v} option prints the system version
string and time stamp on standard output and exits
(e.g. @code{@value{VERSION}} for Gambit @value{VERSION}). Runtime
options are explained in @ref{Runtime options}.
@menu
* GSI interactive mode:: Interactive mode
* GSI batch mode:: Batch mode
* GSI customization:: Customization
* GSI exit status:: Process exit status
* Scheme scripts:: Scheme scripts
@end menu
@node GSI interactive mode, GSI batch mode, GSI, GSI
@section Interactive mode
In interactive mode a read-eval-print loop (REPL) is started for the
user to interact with the interpreter. At each iteration of this loop
the interpreter displays a prompt, reads a command and executes it.
The commands can be expressions to evaluate (the typical case)
or special commands related to debugging, for example @samp{,q} to
terminate the process (for a complete list of commands see
@ref{Debugging}). Most commands produce some output, such as the
value or error message resulting from an evaluation.
The input and output of the interaction is done on the
@dfn{interaction channel}. The interaction channel can be specified
through the runtime options but if none is specified the system uses a
reasonable default that depends on the system's configuration. When
the system's runtime library was built with support for GUIDE, the
Gambit Universal IDE (with the command @samp{configure
--enable-guide}) the interaction channel corresponds to the
@dfn{console window} of the primordial thread (for details see
@ref{GUIDE}), otherwise the interaction channel is the user's
@dfn{console}, also known as the @dfn{controlling terminal} in the
UNIX world. When the REPL starts, the ports associated with
@samp{(current-input-port)}, @samp{(current-output-port)} and
@samp{(current-error-port)} all refer to the interaction channel.
Expressions are evaluated in the global @dfn{interaction environment}.
The interpreter adds to this environment any definition entered using
the @code{define} and @code{define-macro}
special forms. Once the evaluation of an expression is completed, the
value or values resulting from the evaluation are output to the
interaction channel by the pretty printer. The special ``void''
object is not output. This object is returned by most procedures and
special forms which the Scheme standard defines as returning an
unspecified value (e.g. @code{write}, @code{set!}, @code{define}).
Here is a sample interaction with @code{gsi}:
@smallexample
$ @b{gsi}
Gambit @value{VERSION}
> @b{(define (fact n) (if (< n 2) 1 (* n (fact (- n 1)))))}
> @b{(map fact '(1 2 3 4 5 6))}
(1 2 6 24 120 720)
> @b{(values (fact 10) (fact 40))}
3628800
815915283247897734345611269596115894272000000000
> @b{,q}
@end smallexample
What happens when errors occur is explained in @ref{Debugging}.
@node GSI batch mode, GSI customization, GSI interactive mode, GSI
@section Batch mode
In batch mode the command line arguments denote files to be loaded,
REPL interactions to start (@samp{-} option), and expressions to be
evaluated (@samp{-e} option). Note that the @samp{-} and @samp{-e}
options can be interspersed with the files on the command line and can
occur multiple times. The interpreter processes the command line
arguments from left to right, loading files with the @code{load}
procedure and evaluating expressions with the @code{eval} procedure in
the global interaction environment. After this processing the
interpreter exits.
When the file name has no extension the @code{load} procedure first
attempts to load the file with no extension as a Scheme source file.
If that file doesn't exist it completes the file name with a
@samp{.o@var{n}} extension with the highest consecutive version number
starting with 1, and loads that file as an object file. If that file
doesn't exist the file extensions @samp{.scm} and @samp{.six} will be
tried in that order. When the file name has an extension, the
@code{load} procedure will only attempt to load the file with that
specific name.
When the extension of the file loaded is @samp{.scm} the content of
the file will be parsed using the normal Scheme prefix syntax. When
the extension of the file loaded is @samp{.six} the content of the
file will be parsed using the Scheme infix syntax extension (see
@ref{Scheme infix syntax extension}). Otherwise, @code{gsi} will
parse the file using the normal Scheme prefix syntax.
The ports associated with @samp{(current-input-port)},
@samp{(current-output-port)} and @samp{(current-error-port)} initially
refer respectively to the standard input (@samp{stdin}), standard
output (@samp{stdout}) and the standard error (@samp{stderr}) of the
interpreter. This is true even in REPLs started with the @samp{-}
option. The usual interaction channel (console or IDE's console
window) is still used to read expressions and commands and to display
results. This makes it possible to use REPLs to debug programs which
read the standard input and write to the standard output, even when
these have been redirected.
Here is a sample use of the interpreter in batch mode, under UNIX:
@smallexample
$ @b{cat h.scm}
(display "hello") (newline)
$ @b{cat w.six}
display("world"); newline();
$ @b{gsi h.scm - w.six -e "(pretty-print 1)(pretty-print 2)"}
hello
> @b{(define (display x) (write (reverse (string->list x))))}
> @b{,(c 0)}
(#\d #\l #\r #\o #\w)
1
2
@end smallexample
@node GSI customization, GSI exit status, GSI batch mode, GSI
@section Customization
There are two ways to customize the interpreter. When the interpreter
starts off it tries to execute a @samp{(load "~~lib/gambcext")} (for an
explanation of how file names are interpreted see @ref{Host environment}).
An error is not signaled when the file does not exist. Interpreter
extensions and patches that are meant to apply to all users and all
modes should go in that file.
Extensions which are meant to apply to a single user or to a specific
working directory are best placed in the @dfn{initialization file},
which is a file containing Scheme code. In all modes, the interpreter
first tries to locate the initialization file by searching the following
locations: @file{.gambcini} and @file{~/.gambcini} (with no extension, a
@samp{.scm} extension, and a @samp{.six} extension in that order). The
first file that is found is examined as though the expression
@code{(include @var{initialization-file})} had been entered at the
read-eval-print loop where @var{initialization-file} is the file that
was found. Note that by using an @code{include} the macros defined in
the initialization file will be visible from the read-eval-print loop
(this would not have been the case if @code{load} had been used). The
initialization file is not searched for or examined when the @samp{-f}
option is specified.
@node GSI exit status, Scheme scripts, GSI customization, GSI
@section Process exit status
The status is zero when the interpreter exits normally and is nonzero
when the interpreter exits due to an error. Here is the meaning of
the exit statuses:
@table @code
@item 0
The execution of the primordial thread (i.e. the main thread) did not
encounter any error. It is however possible that other threads
terminated abnormally (by default threads other than the primordial
thread terminate silently when they raise an exception that is not
handled).
@item 64
The runtime options or the environment variable @samp{GAMBCOPT}
contained a syntax error or were invalid.
@item 70
This normally indicates that an exception was raised in the primordial
thread and the exception was not handled.
@item 71
There was a problem initializing the runtime system, for example
insufficient memory to allocate critical tables.
@end table
For example, if the shell is @code{sh}:
@smallexample
$ @b{gsi -:d0 -e "(pretty-print (expt 2 100))"}
1267650600228229401496703205376
$ @b{echo $?}
0
$ @b{gsi -:d0,unknown @r{@i{# try to use an unknown runtime option}}}
$ @b{echo $?}
64
$ @b{gsi -:d0 nonexistent.scm @r{@i{# try to load a file that does not exist}}}
$ @b{echo $?}
70
$ @b{gsi nonexistent.scm}
*** ERROR IN ##main -- No such file or directory
(load "nonexistent.scm")
$ @b{echo $?}
70
@end smallexample
@smallexample
@b{}$ @b{gsi -:m4000000 @r{@i{# ask for a 4 gigabyte heap}}}
*** malloc: vm_allocate(size=528384) failed (error code=3)
*** malloc[15068]: error: Can't allocate region
$ @b{echo $?}
71
@end smallexample
Note the use of the runtime option @samp{-:d0} that prevents error
messages from being output, and the runtime option @samp{-:m4000000}
which sets the minimum heap size to 4 gigabytes.
@node Scheme scripts, , GSI exit status, GSI
@section Scheme scripts
The @code{load} procedure treats specially files that begin with
the two characters @samp{#!} and @samp{@@;}. Such files are called
@dfn{script files}. In addition to indicating that the file is a
script, the first line provides information about the source code
language to be used by the @code{load} procedure. After the two
characters @samp{#!} and @samp{@@;} the system will search for the first
substring matching one of the following language specifying tokens:
@table @code
@item scheme-r4rs
@pindex scheme-r4rs
R4RS language with prefix syntax, case-insensitivity, keyword syntax
not supported
@item scheme-r5rs
@pindex scheme-r5rs
R5RS language with prefix syntax, case-insensitivity, keyword syntax
not supported
@item scheme-ieee-1178-1990
@pindex scheme-ieee-1178-1990
IEEE 1178-1990 language with prefix syntax, case-insensitivity, keyword
syntax not supported
@item scheme-srfi-0
@pindex scheme-srfi-0
R5RS language with prefix syntax and SRFI 0 support
(i.e. @code{cond-expand} special form), case-insensitivity, keyword
syntax not supported
@item gsi-script
@pindex gsi-script
Full Gambit Scheme language with prefix syntax, case-sensitivity, keyword
syntax supported
@item gsc-script
@pindex gsc-script
Full Gambit Scheme language with prefix syntax, case-sensitivity, keyword
syntax supported
@item six-script
@pindex six-script
Full Gambit Scheme language with infix syntax, case-sensitivity, keyword
syntax supported
@end table
If a language specifying token is not found, @code{load} will use the
same language as a nonscript file (i.e. it uses the file extension and
runtime system options to determine the language).
After processing the first line, @code{load} will parse the rest of
the file (using the syntax of the language indicated) and then execute
it. When the file is being loaded because it is an argument on the
interpreter's command line, the interpreter will:
@itemize @bullet{}
@item
@findex command-line
Setup the @code{command-line} procedure so that it returns a list
containing the expanded file name of the script file and the
arguments following the script file on the command line.
This is done before the script is executed. The expanded file name
of the script file can be used to determine the directory that
contains the script (i.e. @code{(path-directory (car (command-line)))}).
@item
After the script is loaded the procedure @code{main} is called with
the command-line arguments. The way this is done depends on the
language specifying token. For @code{scheme-r4rs},
@code{scheme-r5rs}, @code{scheme-ieee-1178-1990}, and
@code{scheme-srfi-0}, the @code{main} procedure is called with the
equivalent of @code{(main (cdr (command-line)))} and @code{main} is
expected to return a process exit status code in the range 0 to 255.
This conforms to the ``Running Scheme Scripts on Unix SRFI'' (SRFI
22). For @code{gsi-script} and @code{six-script} the @code{main}
procedure is called with the equivalent of @code{(apply main (cdr
(command-line)))} and the process exit status code is 0 (@code{main}'s
result is ignored). The Gambit-C system has a predefined @code{main}
procedure which accepts any number of arguments and returns 0, so it
is perfectly valid for a script to not define @code{main} and to do
all its processing with top-level expressions (examples are given in
the next section).
@item
When @code{main} returns, the interpreter exits. The command-line
arguments after a script file are consequently not processed (however
they do appear in the list returned by the @code{command-line}
procedure, after the script file's expanded file name, so it is up to
the script to process them).
@end itemize
@menu
* Scripts under UNIX and Mac OS X:: Scripts under UNIX and Mac OS X
* Scripts under Microsoft Windows:: Scripts under Microsoft Windows
* Compiling scripts:: Compiling scripts
@end menu
@node Scripts under UNIX and Mac OS X, Scripts under Microsoft Windows, Scheme scripts, Scheme scripts
@subsection Scripts under UNIX and Mac OS X
Under UNIX and Mac OS X, the Gambit-C installation process creates the
executable @samp{gsi} and also the executables @samp{six},
@samp{gsi-script}, @samp{six-script}, @samp{scheme-r5rs},
@samp{scheme-srfi-0}, etc as links to @samp{gsi}. A Scheme script
need only start with the name of the desired Scheme language variant
prefixed with @samp{#!} and the directory where the Gambit-C
executables are stored. This script should be made executable by
setting the execute permission bits (with a @samp{chmod +x
@var{script}}). Here is an example of a script which lists on standard
output the files in the current directory:
@smallexample
@b{}#!/usr/local/Gambit-C/bin/gsi-script
(for-each pretty-print (directory-files))
@end smallexample
Here is another UNIX script, using the Scheme infix syntax extension,
which takes a single integer argument and prints on standard output the
numbers from 1 to that integer:
@smallexample
@b{}#!/usr/local/Gambit-C/bin/six-script
void main (obj n_str)
@{
int n = \string->number(n_str);
for (int i=1; i<=n; i++)
\pretty-print(i);
@}
@end smallexample
For maximal portability it is a good idea to start scripts indirectly
through the @samp{/usr/bin/env} program, so that the executable of the
interpreter will be searched in the user's @samp{PATH}. This is what
SRFI 22 recommends. For example here is a script that mimics the UNIX
@samp{cat} utility for text files:
@smallexample
@b{}#!/usr/bin/env gsi-script
(define (display-file filename)
(display (call-with-input-file filename
(lambda (port)
(read-line port #f)))))
(for-each display-file (cdr (command-line)))
@end smallexample
@node Scripts under Microsoft Windows, Compiling scripts, Scripts under UNIX and Mac OS X, Scheme scripts
@subsection Scripts under Microsoft Windows
Under Microsoft Windows, the Gambit-C installation process creates the
executable @samp{gsi.exe} and @samp{six.exe} and also the batch files
@samp{gsi-script.bat}, @samp{six-script.bat}, @samp{scheme-r5rs.bat},
@samp{scheme-srfi-0.bat}, etc which simply invoke @samp{gsi.exe} with
the same command line arguments. A Scheme script need only start with
the name of the desired Scheme language variant prefixed with
@samp{@@;}. A UNIX script can be converted to a Microsoft Windows
script simply by changing the first line and storing the script in a
file whose name has a @samp{.bat} or @samp{.cmd} extension:
@smallexample
@b{}@@;gsi-script %~f0 %*
(display "files:\n")
(pretty-print (directory-files))
@end smallexample
Note that Microsoft Windows always searches executables in the user's
@samp{PATH}, so there is no need for an indirection such as the UNIX
@samp{/usr/bin/env}. However the first line must end with @samp{%~f0
%*} to pass the expanded filename of the script and command line
arguments to the interpreter.
@node Compiling scripts, , Scripts under Microsoft Windows, Scheme scripts
@subsection Compiling scripts
A script file can be compiled using the Gambit Scheme compiler
(@pxref{GSC}) into a dynamically loadable object file or into a
standalone executable. The first line of the script will provide
information to the compiler on which language to use. The first line
also provides information on which runtime options to use when
executing the script. The compiled script will be executed similarly
to an interpreted script (i.e. the list of command line arguments
returned by the @code{command-line} procedure and the invocation of
the @code{main} procedure).
For example:
@smallexample
$ @b{cat square.scm}
#!/usr/local/Gambit-C/bin/gsi-script
(define (main arg)
(pretty-print (expt (string->number arg) 2)))
$ @b{gsi square 30 @r{@i{# will load square.scm}}}
900
$ @b{gsc square}
$ @b{gsi square 30 @r{@i{# will load square.o1}}}
900
@end smallexample
@node GSC, Runtime options, GSI, Top
@chapter The Gambit Scheme compiler
@cindex compiler
@cindex interpreter
Synopsis:
@example
@b{}gsc @r{[}-:@r{@var{runtimeoption}},@dots{}@r{]} @r{[}-i@r{]} @r{[}-f@r{]} @r{[}-v@r{]}
@r{[}-prelude @r{@var{expressions}}@r{]} @r{[}-postlude @r{@var{expressions}}@r{]}
@r{[}-dynamic@r{]} @r{[}-cc-options @r{@var{options}}@r{]}
@r{[}-ld-options-prelude @r{@var{options}}@r{]} @r{[}-ld-options @r{@var{options}}@r{]}
@r{[}-warnings@r{]} @r{[}-verbose@r{]} @r{[}-report@r{]} @r{[}-expansion@r{]} @r{[}-gvm@r{]}
@r{[}-debug@r{]} @r{[}-debug-location@r{]} @r{[}-debug-source@r{]}
@r{[}-debug-environments@r{]} @r{[}-track-scheme@r{]}
@r{[}-o @r{@var{output}}@r{]} @r{[}-c@r{]} @r{[}-keep-c@r{]} @r{[}-link@r{]} @r{[}-flat@r{]} @r{[}-l @r{@var{base}}@r{]}
@r{[}@r{[}-@r{]} @r{[}-e @r{@var{expressions}}@r{]} @r{[}@r{@var{file}}@r{]}@r{]}@dots{}
@end example
@menu
* GSC interactive mode:: Interactive mode
* GSC customization:: Customization
* GSC batch mode:: Batch mode
* Link files:: Link files
* Procedures specific to compiler:: Procedures specific to compiler
@end menu
@node GSC interactive mode, GSC customization, GSC, GSC
@section Interactive mode
When no command line argument is present other than options the
compiler behaves like the interpreter in interactive mode. The only
difference with the interpreter is that the compilation related
procedures listed in this chapter are also available
(i.e. @code{compile-file}, @code{compile-file-to-c}, etc).
@node GSC customization, GSC batch mode, GSC interactive mode, GSC
@section Customization
Like the interpreter, the compiler will examine the initialization
file unless the @samp{-f} option is specified.
@node GSC batch mode, Link files, GSC customization, GSC
@section Batch mode
@pindex gsc
@flindex .scm
@flindex .six
@flindex .c
@flindex @var{file}.scm
@flindex @var{file}.six
@flindex @var{file}.c
In batch mode @code{gsc} takes a set of file names (with either no
extension, or a @samp{.c} extension, or some other extension) on the
command line and compiles each Scheme file into a C file.
The extension can be omitted from @var{file} when the Scheme file has a
@samp{.scm} or @samp{.six} extension. When the extension of the
Scheme file is @samp{.six} the content of the file will be parsed
using the Scheme infix syntax extension (see @ref{Scheme infix syntax
extension}). Otherwise, @code{gsc} will parse the Scheme file using the
normal Scheme prefix syntax. Files with a @samp{.c} extension must
have been previously produced by @code{gsc} and are used by
Gambit's linker.
For each Scheme file a C file @samp{@var{file}.c} will be produced.
The C file's name is the same as the Scheme file, but the extension is
changed to @samp{.c}. By default the C file is created in the same
directory as the Scheme file. This default can be overridden with the
compiler's @samp{-o} option.
The C files produced by the compiler serve two purposes. They will be
processed by a C compiler to generate object files, and they also
contain information to be read by Gambit's linker to generate a
@dfn{link file}. The link file is a C file that collects various
linking information for a group of modules, such as the set of all
symbols and global variables used by the modules.
@opindex -link
The linker is only invoked when the @samp{-link}
option appears on the command line.
Compiler options must be specified before the first file name and
after the @samp{-:} runtime option (@pxref{Runtime options}). If
present, the @samp{-i}, @samp{-f}, and @samp{-v} compiler options
must come first. The available options are:
@cindex compiler options
@cindex options, compiler
@table @code
@item -i
Force interpreter mode.
@item -f
Do not examine the initialization file.
@item -v
Print the system version string, system time stamp and operating
system type on standard output and exit.
@item -prelude @var{expressions}
Add expressions to the top of the source code being compiled.
@item -postlude @var{expressions}
Add expressions to the bottom of the source code being compiled.
@item -cc-options @var{options}
Add options to the command that invokes the C compiler.
@item -ld-options-prelude @var{options}
Add options to the command that invokes the C linker.
@item -ld-options @var{options}
Add options to the command that invokes the C linker.
@item -warnings
Display warnings.
@item -verbose
Display a trace of the compiler's activity.
@item -report
Display a global variable usage report.
@item -expansion
Display the source code after expansion.
@item -gvm
Generate a listing of the GVM code.
@item -debug
Include all debugging information in the code generated.
@item -debug-location
Include source code location debugging information in the code generated.
@item -debug-source
Include the source code debugging information in the code generated.
@item -debug-environments
Include environment debugging information in the code generated.
@item -track-scheme
Generate @samp{#line} directives referring back to the Scheme code.
@item -o @var{output}
Set name of output file or directory where output file(s) are written.
@item -dynamic
Compile Scheme source files to dynamically loadable object
files (this is the default).
@item -keep-c
Keep the intermediate @samp{.c} file that is generated when
compiling to a dynamically loadable object file.
@item -c
Compile Scheme source files to C without generating link file.
@item -link
Compile Scheme source files to C and generate a link file.
@item -flat
Generate a flat link file instead of the default incremental link file.
@item -l @var{base}
Specify the link file of the base library to use for the link.
@item -
Start REPL interaction.
@item -e @var{expressions}
Evaluate expressions in the interaction environment.
@end table
@opindex -i
The @samp{-i} option forces the compiler to process the remaining
command line arguments like the interpreter.
@opindex -prelude
The @samp{-prelude} option adds the specified expressions to the top of
the source code being compiled. The main use of this option is to
supply declarations on the command line. For example the following
invocation of the compiler will compile the file @samp{bench.scm} in
unsafe mode:
@smallexample
$ @b{gsc -prelude "(declare (not safe))" bench.scm}
@end smallexample
@opindex -postlude
The @samp{-postlude} option adds the specified expressions to the bottom
of the source code being compiled. The main use of this option is to
supply the expression that will start the execution of the program. For
example:
@smallexample
$ @b{gsc -postlude "(start-bench)" bench.scm}
@end smallexample
@opindex -cc-options
The @samp{-cc-options} option is only meaningful when a dynamically
loadable object file is being generated (neither the @samp{-c} or
@samp{-link} options are used). The @samp{-cc-options} option adds
the specified options to the command that invokes the C compiler. The
main use of this option is to specify the include path, some symbols
to define or undefine, the optimization level, or any C compiler
option that is different from the default. For example:
@smallexample
$ @b{gsc -cc-options "-U___SINGLE_HOST -O2 -I../include" bench.scm}
@end smallexample
@opindex -ld-options-prelude
@opindex -ld-options
The @samp{-ld-options-prelude} and @samp{-ld-options} options are only
meaningful when a dynamically loadable object file is being generated
(neither the @samp{-c} or @samp{-link} options are used). The
@samp{-ld-options-prelude} and @samp{-ld-options} options add the
specified options to the command that invokes the C linker (the
options in @var{ld-options-prelude} are passed to the C linker before
the input file and the options in @var{ld-options} are passed after).
The main use of this option is to specify additional object files or
libraries that need to be linked, or any C linker option that is
different from the default (such as the library search path and flags
to select between static and dynamic linking). For example:
@smallexample
$ @b{gsc -ld-options "-L/usr/X11R6/lib -lX11 -dynamic" bench.scm}
@end smallexample
@opindex -warnings
The @samp{-warnings} option displays on standard output all warnings
that the compiler may have.
@opindex -verbose
The @samp{-verbose} option displays on standard output a trace of the
compiler's activity.
@opindex -report
The @samp{-report} option displays on standard output a global
variable usage report. Each global variable used in the program is
listed with 4 flags that indicate whether the global variable is
defined, referenced, mutated and called.
@opindex -expansion
The @samp{-expansion} option displays on standard output the source code
after expansion and inlining by the front end.
@opindex -gvm
The @samp{-gvm} option generates a listing of the intermediate code
for the ``Gambit Virtual Machine'' (GVM) of each Scheme file on
@samp{@var{file}.gvm}.
@opindex -debug
The @samp{-debug} option causes debugging information to be saved in
the code generated. It is equivalent to the combination of the
@samp{-debug-location} option, the @samp{-debug-source} option and the
@samp{-debug-environments} option. Note that the debugging
information will substantially increase the C compilation time and the
size of the generated code. When compiling a 3000 line Scheme file it
was observed that the total compilation time is 500% longer and the
executable code is 150% bigger.
@opindex -debug-location
The @samp{-debug-location} option causes source code location
debugging information to be saved in the code generated. With this
option run time error messages indicate the location of the error in
the source code file. When compiling a 3000 line Scheme file it was
observed that the total compilation time is 200% longer and the
executable code is 60% bigger.
@opindex -debug-source
The @samp{-debug-source} option causes source code debugging
information to be saved in the code generated. With this option run
time error messages indicate the source code, the backtraces are more
precise, and the @code{pp} procedure will display the source code of
compiled procedures. When compiling a 3000 line Scheme file it was
observed that the total compilation time is 90% longer and the
executable code is 90% bigger.
@opindex -debug-environments
The @samp{-debug-environments} option causes environment debugging
information to be saved in the code generated. With this option the
debugger will have access to the environments of the continuations.
In other words the local variables defined in compiled procedures (and
not optimized away by the compiler) will be shown by the @samp{,e}
REPL command. When compiling a 3000 line Scheme file it was observed
that the total compilation time is 70% longer and the executable code
is 40% bigger.
@opindex -track-scheme
The @samp{-track-scheme} options causes the generation of @samp{#line}
directives that refer back to the Scheme source code. This allows the
use of a C debugger or profiler to debug Scheme code.
@opindex -o @var{output}
The @samp{-o} option sets the filename of the output file, or the
directory in which the output file(s) generated by the compiler are
written.
@opindex -c
@opindex -dynamic
@opindex -link
@opindex -keep-c
@flindex @var{last}_.c
If the @samp{-link} option appears on the command line, the Gambit
linker is invoked to generate the link file from the set of C files
specified on the command line or produced by the Gambit compiler.
By default the link file is @samp{@var{last}_.c}, where @samp{@var{last}.c} is
the last file in the set of C files. When the @samp{-c} option is
specified, the Scheme source files are compiled to C files. If
neither the @samp{-link} or @samp{-c} options appear on the command
line, the Scheme source files are compiled to dynamically loadable
object files (@samp{.o@var{n}} extension). When a dynamically
loadable object file is generated the @samp{-keep-c} option will
prevent the deletion of the intermediate @samp{.c} file that is
generated. Note that in this case the intermediate @samp{.c} file
will be generated in the same directory as the Scheme source file
even if the @samp{-o} option is used.
@opindex -flat
The @samp{-flat} option is only meaningful when a link file is being
generated (i.e. the @samp{-link} option also appears on the command
line). The @samp{-flat} option directs the Gambit linker to generate
a flat link file. By default, the linker generates an incremental
link file (see the next section for a description of the two types of
link files).
@opindex -l @var{base}
The @samp{-l} option is only meaningful when an incremental link file
is being generated (i.e. the @samp{-link} option appears on the
command line and the @samp{-flat} option is absent). The @samp{-l}