.\" dummy line
.TH SCM 1 "April 2006"
.UC 4
.SH NAME
scm \- a Scheme Language Interpreter
.SH SYNOPSIS
.B scm
[-a
.I kbytes
]
[-muvqib]
[--version]
[--help]
.br
[[-]-no-init-file] [-p
.I int
] [-r
.I feature
] [-h
.I feature
]
.br
[-d
.I filename
] [-f
.I filename
] [-l
.I filename
]
.br
[-c
.I expression
] [-e
.I expression
]
[-o
.I dumpname
]
.br
[-- | - | -s] [
.I filename
] [
.I arguments ...
]
.br
.sp 0.3
.SH DESCRIPTION
.I Scm
is a Scheme interpreter.
.PP
Upon startup
.I scm
loads the file specified by by the environment variable SCM_INIT_PATH
or by the parameter IMPLINIT in the makefile (or scmfig.h) if
SCM_INIT_PATH is not defined.  The makefiles attempt to set IMPLINIT
to "Init.scm" in the source directory.

Unless the option
.I -no-init-file
or
.I --no-init-file
occurs in the command line or if
.I scm
is being invoked as a script, "Init.scm" checks to see if there is
file "ScmInit.scm" in the path specified by the environment variable
HOME (or in the current directory if HOME is undefined).  If it finds
such a file, then it is loaded.

"Init.scm" then looks for command input from one of three sources:
From an option on the command line, from a file named on the command
line, or from standard input.

.SH OPTIONS
The options are processed in the order specified on the command line.
.TP 5
.BI -a kbytes
specifies that
.I scm
should allocate an initial heapsize of
.I kbytes.
This option, if present, must be the first on the command line.
.TP
.BI -no-init-file
Inhibits the loading of "ScmInit.scm" as described above.
.TP
.BI -e expression
.TP
.BI -c expression
specifies that the scheme expression
.I expression
is to be evaluated.  These options are inspired by
.I perl
and
.I sh
respectively.
On Amiga systems the entire option and argument need to be enclosed in
quotes.  For instance "-e(newline)".
.TP
.BI -r feature
requires
.I feature.
This will load a file from SLIB if that
.I feature
is not already supported.  If
.I feature
is 2, 3, 4, or 5
.I scm
will require the features necessary to support R2RS, R3RS, R4RS, or
R5RS, respectively.
.TP
.BI -h feature
provides
.I feature.
.TP
.BI -l filename
.TP
.BI -f filename
loads
.I filename.
.I Scm
will load the first (unoptioned) file named on the command line if no
-c, -e, -f, -l, or -s option precedes it.
.TP
.BI -d filename
opens (read-only) the extended relational database
.I filename.
If
.I filename
contains initialization code, it will be run when the database is
opened.
.TP
.BI -o dumpname
saves the current SCM session as the executable program 
.I dumpname.
This option works only in SCM builds supporting 
.BI dump.

If options appear on the command line after 
.I -o dumpname,
then the saved session will continue with processing those options
when it is invoked.  Otherwise the (new) command line is processed as
usual when the saved image is invoked.
.TP
.BI -p level
sets the prolixity (verboseness) to
.I level.
This is the same as the
.I scm
command (verbose
.I level
).
.TP
.B -v
(verbose mode) specifies that
.I scm
will print prompts, evaluation times, notice of loading files, and
garbage collection statistics.  This is the same as
.I -p3.
.TP
.B -q
(quiet mode) specifies that
.I scm
will print no extra information.  This is the same as
.I -p0.
.TP
.B -m
specifies that subsequent loads, evaluations, and user interactions
will be with R4RS macro capability.  To use a specific R4RS macro
implementation from SLIB (instead of SLIB's default) put
.I -r macropackage
before
.I -m
on the command line.
.TP
.B -u
specifies that subsequent loads, evaluations, and user interactions
will be without R4RS macro capability.  R4RS macro capability can be
restored by a subsequent
.I -m
on the command line or from Scheme code.
.TP
.B -i
specifies that
.I scm
should run interactively.  That means that
.I scm
will not terminate until the
.I (quit)
or
.I (exit)
command is given, even if there are errors.  It also sets the
prolixity level to 2 if it is less than 2.  This will print
prompts, evaluation times, and notice of loading files.  The prolixity
level can be set by subsequent options.  If
.I scm
is started from a tty, it will assume that it should be interactive
unless given a subsequent
.I -b
option.
.TP
.B -b
specifies that
.I scm
should run non-interactively.  That means that
.I scm
will terminate after processing the command line or if there are
errors.
.TP
.B -s
specifies, by analogy with
.I sh,
that further options are to be treated as program arguments.
.TP
.BI -
.BI --
specifies that there are no more options on the command line.
.SH ENVIRONMENT VARIABLES
.TP 5
.B SCM_INIT_PATH
is the pathname where
.I scm
will look for its initialization code.  The default is the file
"Init.scm" in the source directory.
.TP
.B SCHEME_LIBRARY_PATH
is the SLIB Scheme library directory.
.TP
.B HOME
is the directory where "Init.scm" will look for the user
initialization file "ScmInit.scm".
.SH SCHEME VARIABLES
.TP 5
.B *argv*
contains the list of arguments to the program.
.I *argv*
can change during argument processing.  This list is
suitable for use as an argument to SLIB
.I getopt.
.TP
.B *R4RS-macro*
controls whether loading and interaction support R4RS macros.  Define
this in "ScmInit.scm" or files specified on the command line.  This
can be overridden by subsequent -m and -u options.
.TP
.B *interactive*
controls interactivity as explained for the -i and -b options.  Define
this in "ScmInit.scm" or files specified on the command line.  This
can be overridden by subsequent -i and -b options.
.SH EXAMPLES
.ne 5
.TP 5
% scm foo.scm arg1 arg2 arg3
.br	
Load and execute the contents of foo.scm.  Parameters
arg1 arg2 and arg3 are stored in the global list *argv*.
.TP
% scm -f foo.scm arg1 arg2 arg3
.br
The same.
.TP
% scm -s foo.scm arg1 arg2
.br
Set *argv* to ("foo.scm" "arg1" "arg2") and enter interactive session.
.TP
% scm -e '(display (list-ref *argv* *optind*))' bar
.br
Print ``bar''
.TP
% scm -rpretty-print -r format -i
.br
Load pretty-print and format and enter interactive mode.
.TP
% scm -r5
.br
Load dynamic-wind, values, and R4RS macros and enter interactive (with
macros) mode.
.TP
% scm -r5 -r4
.br
Like above but rev4-optional-procedures are also loaded.
.SH FEATURES
.PP
Runs under Amiga, Atari-ST, MacOS, MS-DOS, OS/2, NOS/VE, Unicos, VMS,
Unix and similar systems.  Support for ASCII and EBCDIC character
sets.
.PP
Conforms to Revised^5 Report on the Algorithmic Language Scheme
and the IEEE P1178 specification.
.PP
Support for SICP, R2RS, R3RS, and R4RS scheme code.
.PP
Many Common Lisp functions:
logand, logor, logxor, lognot, ash, logcount, integer-length,
bit-extract, defmacro, macroexpand, macroexpand1, gentemp,
defvar, force-output, software-type, get-decoded-time,
get-internal-run-time, get-internal-real-time, delete-file,
rename-file, copy-tree, acons, and eval.
.PP
Char-code-limit, most-positive-fixnum, most-negative-fixnum,
and internal-time-units-per-second constants.  *Features* and
*load-pathname* variables.
.PP
Arrays and bit-vectors.  String ports and software emulation ports.
I/O extensions providing most of ANSI C and POSIX.1 facilities.
.PP
User definable responses to interrupts and errors,
Process-synchronization primitives, String regular expression matching,
and the CURSES screen management package.
.PP
Available add-on packages including an interactive debugger, database,
X-window graphics, BGI graphics, Motif, and Open-Windows packages.
.PP
A compiler (HOBBIT, available separately) and dynamic linking of
compiled modules.
.PP
Setable levels of monitoring and timing information printed
interactively (the `verbose' function).  Restart, quit, and exec.
.SH FILES
.TP
scm.texi
.br
Texinfo documentation of
.I scm
enhancements, internal representations, and how to extend or include
.I scm
in other programs.
.SH AUTHORS
Aubrey Jaffer (jaffer @ alum.mit.edu)
.br
Radey Shouman (shouman @ ne.mediaone.net)
.SH BUGS
.SH SEE ALSO
The SCM home-page:
.br
http://swissnet.ai.mit.edu/~jaffer/SCM.html
.PP
The Scheme specifications for details on specific procedures
(http://swissnet.ai.mit.edu/ftpdir/scheme-reports/) or
.PP
IEEE Std 1178-1990,
.br
IEEE Standard for the Scheme Programming Language,
.br
Institute of Electrical and Electronic Engineers, Inc.,
.br
New York, NY, 1991
.PP
Brian Harvey and Matthew Wright
.br
Simply Scheme: Introducing Computer Science_
.br
MIT Press, 1994 ISBN 0-262-08226-8
.PP
R. Kent Dybvig, The Scheme Programming Language,
.br
Prentice-Hall Inc, Englewood Cliffs, New Jersey 07632, USA
.PP
H. Abelson, G. J. Sussman, and J. Sussman,
.br
Structure and Interpretation of Computer Programs,
.br
The MIT Press, Cambridge, Massachusetts, USA