racket/scheme.1.in
dybvig 7d145e37a8 Various enhancements and fixes highlighted by profiling performance
and functionality improvements (including support for measuring
coverage), primitive argument-checking fixes, and object-file changes
resulting in reduced load times (and some backward incompatibility):
- annotations are now preserved in object files for debug
  only, for profiling only, for both, or not at all, depending
  on the settings of generate-inspector-information and
  compile-profile.  in particular, when inspector information
  is not enabled but profiling is, source information does
  not leak into error messages and inspector output, though it is
  still available via the profile tools.  The mechanics of this
  involved repurposing the fasl a? parameter to hold an annotation
  flags value when it is not #f and remaking annotations with
  new flags if necessary before emitting them.
    compile.ss, fasl.ss, misc.ms
- altered a number of mats to produce correct results even
  when the 's' directory is profiled.
    misc.ms, cp0.ms, record.ms
- profile-release-counters is now generation-friendly; that is,
  it doesn't look for dropped code objects in generations that have
  not been collected since the last call to profile-release-counters.
  also, it no longer allocates memory when it releases counters.
    pdhtml.ss,
    gc.c, gcwrapper.c, globals.h, prim5.c
- removed unused entry points S_ifile, S_ofile, and S_iofile
    alloc.c, externs.h
- mats that test loading profile info into the compiler's database
  to guide optimization now weed out preexisting entries, in case
  the 's' directory is profiled.
    4.ms, mat.ss, misc.ms, primvars.ms
- counters for dropped code objects are now released at the start
  of each mat group.
    mat.ss
- replaced ehc (enable-heap-check) option with hci (heap-check-interval)
  option that allows heap checks to be performed periodically rather
  than on each collection.  hci=0 is equivalent to ehc=f (disabling
  heap checks) and hci=1 is equivalent to ehc=t (enabling heap
  checks every collection), while hci=100 enables heap checks only
  every 100th collection.  allx and bullyx mats use this feature
  to reduce heap-checking overhead to a more reasonable level.  this
  is particularly important when the 's' directory is profiled,
  since the amount of static memory to be checked is greatly increased
  due to the counters.
    mats/Mf-base, mat.ss, primvars.ms
- added a mat that calls #%show-allocation, which was otherwise not
  being tested.
    misc.ms
- removed a broken primvars mat and updated two others.  in each case,
  the mat was looking for information about primitives in the wrong
  (i.e., old) place and silently succeeding when it didn't find any
  primitives to tests.  the revised mats (along with a few others) now
  check to make sure at least one identifier has the information they
  look for.  the removed mat was checking for library information that
  is now compiled in, so the mat is now unnecessary.  the others were
  (not) doing argument-error checks.  fixing these turned up a handful of
  problems that have also been fixed: a couple of unbound variables in the
  mat driver, two broken primdata declarations, a tardy argument check
  by profile-load-data, and a bug in char-ready?, which was requiring
  an argument rather than defaulting it to the current input port.
    primdata.ss, pdhtml.ss, io.ms,
    primdvars.ms, 4.ms, 6.ms, misc.ms, patch*
- added initial support for recording coverage information.  when the
  new parameter generate-covin-files is set, the compiler generates
  .covin files containing the universe of all source objects for which
  profile forms are present in the expander output.  when profiling
  and generation of covin files are enabled in the 's' directory, the
  mats optionally generate .covout files for each mat file giving
  the subset of the universe covered by the mat file, along with an
  all.covout in each mat output directory aggregating the coverage
  for the directory and another all.covout in the top-level mat
  directory aggregating the coverage for all directories.
    back.ss, compile.ss, cprep.ss, primdata.ss, s/Mf-base,
    mat.ss, mats/Mf-base, mats/primvars.ms
- support for generating covout files is now built in.  with-coverage-output
  gathers and dumps coverage information, and aggregate-coverage-output
  combines (aggregates) covout files.
    pdhtml.ss, primdata.ss, compile.ss,
    mat.ss, mats/Mf-base, primvars.ms
- profile-clear now adjusts active coverage trackers to avoid losing
  coverage information.
    pdhtml.ss,
    prim5.c
- nested with-coverage calls are now supported.
    pdhtml.ss
- switched to a more compact representation for covin and covout files;
  reduces disk space (compressed or not) by about a factor of four
  and read time by about a factor of two with no increase in write time.
    primdata.ss, pdhtml.ss, cprep.ss, compile.ss,
    mat.ss, mats/Mf-base
- added support for determining coverage for an entire run, including
  coverage for expressions hit during boot time.  'all' mats now produce
  run.covout files in each output directory, and 'allx' mats produce
  an aggregate run.covout file in the mat directory.
    pdhtml.ss,
    mat.ss, mats/Mf-base
- profile-release-counters now adjusts active coverage trackers to
  account for the counters that have been released.
    pdhtml.ss,
    prim5.c
- replaced the artificial "examples" target with a real "build-examples"
  target so make won't think it always has to mats that depend upon
  the examples directory having been compiled.  mats make clean now
  runs make clean in the examples directory.
    mats/Mf-base
  importing a library from an object file now just visits the object
  file rather than doing a full load so that the run-time code for
  the library is not retained.  The run-time code is still read
  because the current fasl format forces the entire file to be read,
  but not retaining the code can lower heap size and garbage-collection
  cost, particularly when many object-code libraries are imported.
  The downside is that the file must be revisited if the run-time
  code turns out to be required.   This change exposed several
  places where the code was failing to check if a revisit is needed.
    syntax.ss,
    7.ms, 8.ms, misc.ms, root-experr*
- fixed typos: was passing unquoted load rather than quoted load
  to $load-library along one path (where it is loading source code
  and therefore irrelevant), and was reporting src-path rather than
  obj-path in a message about failing to define a library.
    syntax.ss
- compile-file and friends now put all recompile information in
  the first fasl object after the header so the library manager can
  find it without loading the entire fasl file.  The library manager
  now does so.  It also now checks to see if library object files
  need to be recreated before loading them rather than loading them and
  possibly recompiling them after discovering they are out of date, since
  the latter requires loading the full object file even if it's out of
  date, while the former takes advantage of the ability to extract just
  recompile information.  as well as reducing overhead, this eliminates
  possibly undesirable side effects, such as creation and registration
  of out-of-date nongenerative record-type descriptors.  because the
  library manager expects to find recompile information at the front of
  an object file, it will not find all recompile information if object
  files are "catted" together.  also, compile-file has to hold in memory
  the object code for all expressions in the file so that it can emit the
  unified recompile information, rather than writing to the object file
  incrementally, which can significantly increase the memory required
  to compile a large file full of individual top-level forms.  This does
  not affect top-level programs, which were already handled as a whole,
  or a typical library file that contains just a single library form.
    compile.ss, syntax.ss
- the library manager now checks include files before library dependencies
  when compile-imported-libraries is false (as it already did when
  compile-imported-libraries is true) in case a source change affects
  the set of imported libraries.  (A library change can affect the set
  of include files as well, but checking dependencies before include
  files can cause unneeded libraries to be loaded.)  The include-file
  check is based on recompile-info rather than dependencies, but the
  library checks are still based on dependencies.
    syntax.ss
- fixed check for binding of scheme-version. (the check prevents
  premature treatment of recompile-info records as Lexpand forms
  to be passed to $interpret-backend.)
    scheme.c
- strip-fasl-file now preserves recompile-info when compile-time info
  is stripped.
    strip.ss
- removed include-req* from library/ct-info and ctdesc records; it
  is no longer needed now that all recompile information is maintained
  separately.
    expand-lang.ss, syntax.ss, compile.ss, cprep.ss, syntax.ss
- changed the fasl format and reworked a lot of code in the expander,
  compiler, fasl writer, and fasl reader to allow the fasl reader
  to skip past run-time information when it isn't needed and
  compile-time information when it isn't needed.  Skipping past
  still involves reading and decoding when encrypted, but the fasl
  reader no longer parses or allocates code and data in the portions
  to be skipped.  Side effects of associating record uids with rtds
  are also avoided, as are the side effects of interning symbols
  present only in the skipped data.  Skipping past code objects
  also reduces or eliminates the need to synchronize data and
  instruction caches.  Since the fasl reader no longer returns
  compile-time (visit) or run-time (revisit) code and data when not
  needed, the fasl reader no longer wraps these objects in a pair
  with a 0 or 1 visit or revisit marker.  To support this change,
  the fasl writer generates separate top-level fasl entries (and
  graphs) for separate forms in the same top-level source form
  (e.g., begin or library).  This reliably breaks eq-ness of shared
  structure across these forms, which was previously broken only
  when visit or revisit code was loaded at different times (this
  is an incompatible change).  Because of the change, fasl "groups"
  are no longer needed, so they are no longer handled.
    7.ss, cmacros.ss, compile.ss, expand-lang.ss, strip.ss,
    externs.h, fasl.c, scheme.c,
    hash.ms
- the change above is surfaced in an optional fasl-read "situation"
  argument (visit, revisit, or load).  The default is load.  visit
  causes it to skip past revisit code and data; revisit causes it
  to skip past visit code and data; and load causes it not to skip
  past either.  visit-revisit data produced by (eval-when (visit
  revisit) ---) is never skipped.
    7.ss, primdata.ss,
    io.stex
- to improve compile-time and run-time error checking, the
  Lexpand recompile-info, library/rt-info, library-ct-info, and
  program-info forms have been replaced with list-structured forms,
  e.g., (recompile-info ,rcinfo).
    expand-lang.ss, compile.ss, cprep.ss, interpret.ss, syntax.ss
- added visit-compiled-from-port and revisit-compiled-from-port
  to complement the existing load-compiled-from-port.
    7.ss, primdata.ss,
    7.ms,
    system.stex
- increased amount read when seeking an lz4-encrypted input
  file from 32 to 1024 bytes at a time
    compress-io.c
- replaced the fasl a? parameter value #t with an "all" flag value
  so it's value is consistently a mask.
    cmacros.ss, fasl.ss, compile.ss
- split off profile mats into a separate file
    misc.ms, profile.ms (new), root-experr*, mats/Mf-base
- added coverage percent computations to mat allx/bullyx output
    mat.ss, mats/Mf-base, primvars.ms
- replaced coverage tables with more generic and generally useful
  source tables, which map source objects to arbitrary values.
    pdhtml.ss, compile.ss, cprep.ss, primdata.ss,
    mat.ss, mats/Mf-base, primvars.ms, profile.ms,
    syntax.stex
- reduced profile counting overhead by using calls to fold-left
  instead of calls to apply and map and by using fixnum operations
  for profile counts on 64-bit machines.
    pdhtml.ss
- used a critical section to fix a race condition in the calculations
  of profile counts that sometimes resulted in bogus (including
  negative) counts, especially when the 's' directory is profiled.
    pdhtml.ss
- added discard flag to declaration for hashtable-size
    primdata.ss
- redesigned the printed representation of source tables and rewrote
  get-source-table! to read and store incrementally to reduce memory
  overhead.
    compile.ss
- added generate-covin-files to the set of parameters preserved
  by compile-file, etc.
    compile.ss,
    system.stex
- moved covop argument before the undocumented machine and hostop
  arguments to compile-port and compile-to-port.  removed the
  undocumented ofn argument from compile-to-port; using
  (port-name ip) instead.
    compile.ss, primdata.ss,
    7.ms,
    system.stex
- compile-port now tries to come up with a file position to supply
  to make-read, which it can do if the port's positions are character
  positions (presently string ports) or if the port is positioned
  at zero.
    compile.ss
- audited the argument-type-error fuzz mat exceptions and fixed a
  host of problems this turned up (entries follow).  added #f as
  an invalid argument for every type for which #f is indeed invalid
  to catch places where the maybe- prefix was missing on the argument
  type.  the mat tries hard to determine if the condition raised
  (if any) as the result of an invalid argument is appropriate and
  redirects the remainder to the mat-output (.mo) file prefixed
  with 'Expected error', causing them to show up in the expected
  error output so developers will be encouraged to audit them in
  the future.
    primvars.ms, mat.ss
- added an initial symbol? test on machine type names so we produce
  an invalid machine type error message rather than something
  confusing like "machine type #f is not supported".
    compile.ss
- fixed declarations for many primitives that were specified as
  accepting arguments of more general types than they actually
  accept, such as number -> real for various numeric operations,
  symbol -> endianness for various bytevector operations,
  time -> time-utc for time-utc->date, and list -> list-of-string-pairs
  for default-library-search-handler.   also replaced some of the
  sub-xxxx types with specific types such as sub-symbol -> endianness
  in utf16->string, but only where they were causing issues with
  the primvars argument-type-error fuzz mat.  (this should be done
  more generally.)
    primdata.ss
- fixed incorrect who arguments (was map instead of fold-right,
  current-date instead of time-utc->date); switched to using
  define-who/set-who! generally.
    4.ss, date.ss
- append! now checks all arguments before any mutation
    5_2.ss
- with-source-path now properly supplies itself as who for the
  string? argument check; callers like load now do their own checks.
    7.ss
- added missing integer? check to $fold-bytevector-native-ref whose
  lack could have resulted in a compile-time error.
    cp0.ss
- fixed typo in output-port-buffer-mode error message
    io.ss
- fixed who argument (was fx< rather than fx<?)
    library.ss
- fixed declaration of first source-file-descriptor argument (was
  sfd, now string)
    primdata.ss
- added missing article 'a' in a few error messages
    prims.ss
- fixed the copy-environment argument-type error message for the list
  of symbols argument.
    syntax.ss
- the environment procedure now catches exceptions that occur and
  reraises the exception with itself as who if the condition isn't
  already a who condition.
    syntax.ss
- updated experr and allx patch files for changes to argument-count
  fuzz mat and fixes for problems turned up by them.
    root-experr*, patch*
- fixed a couple of issues setting port sizes: string and bytevector
  output port put handlers don't need room to store the character
  or byte, so they now set the size to the buffer length rather
  than one less.  binary-file-port-clear-output now sets the index
  rather than size to zero; setting the size to zero is inappropriate
  for some types of ports and could result in loss of buffering and
  even suppression of future output.  removed a couple of redundant
  sets of the size that occur immediately after setting the buffer.
    io.ss
- it is now possible to return from a call to with-profile-tracker
  multiple times and not double-count (or worse) any counts.
    pdhtml.ss, profile.ms
- read-token now requires a file position when it is handed a
  source-file descriptor (since the source-file descriptor isn't
  otherwise useful), and the source-file descriptor argument can
  no longer be #f.  the input file position plays the same role as
  the input file position in get-datum/annotations.  these extra
  read-token arguments are now documented.
    read.ss,
    6.ms,
    io.stex
- the source-file descriptor argument to get-datum/annotations can
  no longer be #f.  it was already documented that way.
    read.ss
- read-token and do-read now look for the character-positions port
  flag before asking if the port has port-position, since the latter
  is slightly more expensive.
    read.ss
- rd-error now reports the current port position if it can be determined
  when fp isn't already set, i.e., when reading from a port without
  character positions (presently any non string port) and fp has not
  been passed in explicitly (to read-token or get-datum/annotations).
  the port position might not be a character position, but it should be
  better than nothing.
    read.ss
- added comment noting an invariant for s_profile_release_counters.
    prim5.c
- restored accidentally dropped fasl-write formdef and dropped
  duplicate fasl-read formdef
    io.stex
- added a 'coverage' target that tests the coverage of the Scheme-code
  portions of Chez Scheme by the mats.
    Makefile.in, Makefile-workarea.in
- added .PHONY declarations for all of the targets in the top-level
  and workarea make files, and renamed the create-bintar, create-rpm,
  and create-pkg targets bintar, rpm, and pkg.
    Makefile.in, Makefile-workarea.in
- added missing --retain-static-relocation command-line argument and
  updated the date
    scheme.1.in
- removed a few redundant conditional variable settings
    configure
- fixed declaration of condition wait (timeout -> maybe-timeout)
    primdata.ss

original commit: 88501743001393fa82e89c90da9185fc0086fbcb
2019-09-21 15:37:29 -07:00

800 lines
29 KiB
Groff

.ds s \fIChez Scheme\fP
.ds p \fIPetite Chez Scheme\fP
.if t .ds c caf\o'\'e'
.if n .ds c cafe
.ds ]W
.TH SCHEME 1 "Chez Scheme Version 9.5.3 September 2019"
.SH NAME
\fIChez Scheme\fP
.br
\fIPetite Chez Scheme\fP
.SH SYNOPSIS
\fB{InstallSchemeName}\fP [ \fIoptions\fP ] \fIfile\fP ...
.br
\fB{InstallPetiteName}\fP [ \fIoptions\fP ] \fIfile\fP ...
.SH DESCRIPTION
\*s is a programming language, based on R6RS Scheme, and a
high-performance implementation of that language.
\*s compiles source expressions \fIincrementally\fP to machine code,
providing the speed of compiled code in an interactive system.
.LP
\*p is an interpreted version of \*s that may be
used as a run-time environment for \*s applications or as a
stand-alone Scheme system.
With the exception that the compiler is not present, \*p is 100%
compatible with \*s.
Interpreted code is fast in \*p, but generally not nearly as fast as
compiled code.
Debugging and profiling support is also limited for interpreted
code.
.LP
Scheme is normally used interactively. The system prompts
the user with a right angle bracket (\*(lq>\*(rq) at the beginning of each
input line. Any Scheme expression may be entered. The system evaluates
the expression and prints the result. After printing
the result, the system prompts again for more input.
The user can exit the system by typing
Control-D or by using the procedure \fIexit\fP.
.SH COMMAND-LINE OPTIONS
.LP
\*s recognizes the following command line options:
.TP 1i
.B -q, --quiet
Suppress greeting and prompts.
.TP
.B --script \fIfile\fP
Run \fIfile\fP as a shell script.
.TP
.B --program \fIfile\fP
Run rnrs program in \fIfile\fP as a shell script.
.TP
.B --libdirs \fIdir\fP:...
Set library directories to \fIdir\fP:....
.TP
.B --libexts \fIext\fP:...
Set library extensions to \fIext\fP:....
.TP
.B --compile-imported-libraries
Compile libraries before loading them.
.TP
.B --import-notify
Enable import search messages.
.TP
.B --optimize-level 0 | 1 | 2 | 3
Set optimize level to 0, 1, 2, or 3.
.TP
.B --debug-on-exception
On uncaught exception, call debug.
.TP
.B --eedisable
Disables the expression editor.
.TP
.B --eehistory off | \fIfile\fP
Set expression-editor history file or disable restore and save of history.
.TP
.B --enable-object-counts
Have collector maintain object counts.
.TP
.B --retain-static-relocation
Keep reloc information for compute-size, etc.
.TP
.B -b \fIfile\fP, --boot \fIfile\fP
Load boot code from \fIfile\fP.
.TP
.B --verbose
Trace boot search process.
.TP
.B --version
Print version and exit.
.TP
.B --help
Print brief command-line help and exit.
.TP
.B --
Pass all remaining command-line arguments through to Scheme.
.LP
The following options are recognized but cause the system to print an
error message and exit because saved heaps are not presently supported.
.TP 1in
.B -h \fIfile\fP, --heap \fIfile\fP
.TP
.B -s[\fIlevel\fP] \fIfile\fP, --saveheap[\fIlevel\fP] \fIfile\fP
.TP
.B -c, --compact
.LP
Any remaining command-line arguments are treated as the names of
files to be loaded before Chez Scheme begins interacting with the
user (see COMMAND-LINE FILE ARGUMENTS), unless \*(lq--script\*(rq or
\*(lq--program\*(rq is present, in which case the remaining arguments
are made available to the script via the \fIcommand-line\fP parameter
(see SCHEME SCRIPTS).
.SH WAITERS and CAFES
.LP
Interaction of the system with the user is performed
by a Scheme program called a \fIwaiter\fP, running in a
program state called a \fI\*c\fP. The waiter
merely prompts, reads, evaluates, prints and loops
back for more. It is possible to open up a chain of \*s
\*cs by invoking the \fInew-cafe\fP procedure with no arguments.
New-cafe is also one of the options when an interrupt
occurs. Each \*c has its own reset and exit procedures.
Exiting from one \*c in the chain returns you to the next one
back, and so on, until the entire chain closes and you leave the
system altogether. Sometimes it is useful to
interrupt a long computation by typing the interrupt character,
enter a new \*c to execute something (perhaps to check a status
variable set by computation), and exit the \*c back to the old
computation.
.LP
You can tell what level you are at by the number of angle brackets
in the prompt, one for level one, two for level two, and so on.
Three angle brackets in the prompt means you would have to exit from
three \*cs to get out of \*s. If you wish to abort
from \*s and you are several \*cs deep, the procedure
\fIabort\fP leaves the system directly.
.LP
You can exit the system by typing the end-of-file character
(normally Control-D) or by using the procedure \fIexit\fP.
Typing Control-D is equivalent to (exit), (exit (void)), or
(exit 0), each of which is considered a \*(lqnormal exit\*(rq.
.SH DEBUGGER
Ordinarily, if an exception occurs during interactive use of the system,
the default exception handler displays
the condition with which the exception was raised, saves it for
possibly later use by the debugger, and prints the message
"type (debug) to enter the debugger."
Once in the debugger, the user has the option of inspecting the
raise continuation, i.e., the stack frames of the pending calls.
When an exception occurs in a script or top level program, or when the
standard input and/or output ports are redirected, the default exception
handler does not save the continuation of the exception and does not print
the "type (debug)" message.
.LP
If the parameter debug-on-exception is set to #t, however, the default
exception handler directly invokes debug, whether running interactively or
not, and even when running a script or top-level program.
The \*(lq--debug-on-exception\*(rq option may be used to set
debug-on-exception to #t from the command line, which is particularly
useful when debugging scripts or top-level programs run via the
\*(lq--script\*(rq or \*(lq--program\*(rq options.
.LP
None of this applies to exceptions raised with a non-serious (warning)
condition, for which the default exception handler simply displays the
condition and returns.
.SH KEYBOARD INTERRUPTS
Running programs may be interrupted by typing the interrupt
character (normally Control-C). In response, the
system enters a break handler, which prompts for input with a
\*(lqbreak>\*(rq prompt.
Several commands may be issued to the break handler, including
\*(lqe\*(rq to exit from the handler and continue,
\*(lqr\*(rq to reset to the current \*c,
\*(lqa\*(rq to abort \*s,
\*(lqn\*(rq to enter a new \*c,
\*(lqi\*(rq to inspect the current continuation, and
\*(lqs\*(rq to display statistics about the interrupted program.
While typing an expression to the waiter, the interrupt character
simply resets to the current \*c.
.SH EXPRESSION EDITOR
.LP
When \*s is used interactively in a
shell window, the waiter's \*(lqprompt and read\*(rq
procedure employs an expression editor that permits entry and editing of
single- and multiple-line expressions, automatically indents expressions
as they are entered, and supports name-completion based on the identifiers
defined in the interactive environment.
The expression editor also maintains a history of expressions typed during
and across sessions and supports tcsh(1)-like history movement and search
commands.
Other editing commands include simple cursor movement via
arrow keys, deletion of characters via backspace and delete, and
movement, deletion, and other commands using mostly
emacs key bindings.
.LP
The expression editor does not run if the TERM environment variable is
not set, if the standard input or output files have been redirected, or
if the --eedisable command-line option has been used.
The history is saved across sessions, by default, in the file
\*(lq$HOME/.chezscheme_history\*(rq.
The --eehistory command-line option
can be used to specify a different
location for the history file or to disable the saving and restoring of
the history file.
.LP
Keys for nearly all printing characters (letters, digits, and special
characters) are \*(lqself inserting\*(rq by default.
The open parenthesis, close parenthesis, open bracket, and close bracket
keys are self inserting as well, but also cause the editor to \*(lqflash\*(rq
to the matching delimiter, if any.
Furthermore, when a close parenthesis or close bracket is typed, it is
automatically corrected to match the corresponding open delimiter, if any.
.LP
Key bindings for other keys and key sequences initially recognized by
the expression editor are given below, organized into groups by function.
Some keys or key sequences serve more than one purpose depending upon
context.
For example, tab is used both for identifier completion and for
indentation.
Such bindings are shown in each applicable functional group.
.LP
Multiple-key sequences are displayed with hyphens between the keys of
the sequences, but these hyphens should not be entered.
When two or more key sequences perform the same operation, the sequences
are shown separated by commas.
.LP
Newlines, acceptance, exiting, and redisplay:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
enter, ^M accept balanced entry if used at end of entry;
.br
else add a newline before the cursor and indent
.br
^J accept entry unconditionally
.br
^O insert newline after the cursor and indent
.br
^D exit from the waiter if entry is empty;
.br
else delete character under cursor
.br
^Z suspend to shell if shell supports job control
.br
^L redisplay entry
.br
^L-^L clear screen and redisplay entry
.br
.LP
Basic movement and deletion:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
left, ^B move cursor left
.br
right, ^F move cursor right
.br
up, ^P move cursor up; from top of unmodified entry,
.br
move to preceding history entry.
.br
down, ^N move cursor down; from bottom of unmodified entry,
.br
move to next history entry.
.br
^D delete character under cursor if entry not empty;
.br
else exit from the waiter.
.br
backspace, ^H delete character before cursor
.br
.br
delete delete character under cursor
.br
.LP
Line movement and deletion:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
home, ^A move cursor to beginning of line
.br
end, ^E move cursor to end of line
.br
^K, esc-k delete to end of line or, if cursor is at the end
.br
of a line, join with next line
.br
^U delete contents of current line
.LP
When used on the first line of a multiline entry of which only the first line
is displayed, i.e., immediately after history movement, ^U deletes the
contents of the entire entry, like ^G (described below).
.br
.LP
Expression movement and deletion:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
esc-^F move cursor to next expression
.br
esc-^B move cursor to preceding expression
.br
esc-] move cursor to matching delimiter
.br
^] flash cursor to matching delimiter
.br
esc-^K, esc-delete delete next expression
.br
esc-backspace, esc-^H delete preceding expression
.br
.LP
Entry movement and deletion:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
esc-< move cursor to beginning of entry
.br
esc-> move cursor to end of entry
.br
^G delete current entry contents
.br
^C delete current entry contents; reset to end of history
.br
.LP
Indentation:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
tab re-indent current line if identifier prefix not
.br
just entered; else insert identifier completion
.br
esc-tab re-indent current line unconditionally
.br
esc-q, esc-Q, esc-^Q re-indent each line of entry
.br
.LP
Identifier completion:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
tab insert identifier completion if just entered
.br
identifier prefix; else re-indent current line
.br
tab-tab show possible identifier completions at end of
.br
identifier just typed, else re-indent
.br
^R insert next identifier completion
.LP
If at end of existing identifier, i.e., not one just typed, the first tab
re-indents, the second tab inserts identifier completion, and the third
shows possible completions.
.br
.LP
History movement:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
up, ^P move to preceding entry if at top of unmodified
.br
entry; else move up within entry
.br
down, ^N move to next entry if at bottom of unmodified
.br
entry; else move down within entry
.br
esc-up, esc-^P move to preceding entry from unmodified entry
.br
esc-down, esc-^N move to next entry from unmodified entry
.br
esc-p search backward through history for given prefix
.br
esc-n search forward through history for given prefix
.br
esc-P search backward through history for given string
.br
esc-N search forward through history for given string
.br
.LP
To search, enter a prefix or string followed by one of the search key
sequences.
Follow with additional search key sequences to search further backward or
forward in the history.
For example, enter \*(lq(define\*(rq followed by one or more esc-p key sequences
to search backward for entries that are definitions, or \*(lq(define\*(rq
followed by one or more esc-P key sequences for entries that contain
definitions.
.br
.LP
Word and page movement:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
esc-f, esc-F move cursor to end of next word
.br
esc-b, esc-B move cursor to start of preceding word
.br
^X-[ move cursor up one screen page
.br
^X-] move cursor down one screen page
.br
.LP
Inserting saved text:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
^Y insert most recently deleted text
.br
^V insert contents of window selection/paste buffer
.br
.LP
Mark operations:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
^@, ^space, ^^ set mark to current cursor position
.br
^X-^X move cursor to mark, leave mark at old cursor
.br
^W delete between current cursor position and mark
.br
.LP
Command repetition:
.LP
.ta \w'{xxxxxxxxxxxxx}'u+.25i
esc-^U repeat next command four times
.br
esc-^U-\fIn\fP repeat next command \fIn\fP times
.br
.SH TOP-LEVEL ENVIRONMENT SEMANTICS
.LP
Upon startup, the \*(lqinteraction environment\*(rq used to
hold the top-level bindings for user-defined variables and other
identifiers contains an initial set of bindings, some standard
and some specific to \*s.
Any initial identifier binding may be replaced by redefining
the identifier with a normal top-level definition.
For example, the initial binding for \fIcons\fP can be replaced
with one that performs a "reverse cons" as follows.
.br
.sp
(define cons (lambda (x y) (import scheme) (cons y x)))
.br
.sp
Code entered into the REPL or loaded from a file prior to this
point will still use the original binding for \fIcons\fP.
If you want it to use the new binding, you must reenter or reload
the code.
Furthermore, the initial bindings for variables like \fIcons\fP are immutable,
so you cannot assign one (e.g., via set! or trace) without first defining
it.
This allows the system to check to make sure it receives the expected
two arguments at compile time and generate inline code to allocate
the pair.
This is not the case if \fIcons\fP is redefined, even if redefined to have
the same value, since its value can be changed via set! at any time
during a program run.
.SH COMMAND-LINE FILE ARGUMENTS
.LP
In the normal mode of operation,
the file names on the command line (except for the arguments
to the various command-line options) are
loaded before \*s begins interacting with the user. Each of the
expressions in the loaded files is executed just as if it were
typed by the user in response to a prompt. If you wish to load a
set of definitions each time, consider setting up a shell script to
load the file \*(lq.schemerc\*(rq from your home directory:
.br
.sp
{InstallSchemeName} ${HOME}/.schemerc $*
.sp
.br
If you have a
substantial number of definitions to load each time, it might
be worthwhile to compile the .schemerc file (that is, compile
the definitions and name the resulting object file .schemerc).
.LP
Typically, a Scheme programmer creates a source file of
definitions and other Scheme forms using an editor such as
\fIvi\fP(1) or \fIemacs\fP(1)
and loads the file into Scheme to test them. The
conventional filename extension for \*s source files
is \fI.ss\fP. Such a file may be loaded during a session by typing
(load \*(lq\fIfilename\fP\*(rq), or by specifying the filename on
the command line as mentioned above. Any expression that may be
typed interactively may be placed in a file to be loaded.
.SH SCHEME SCRIPTS
.LP
When the \*(lq--script\*(rq option is used, the named file is
treated as a Scheme shell script, and the script name and remaining
command-line arguments are made available via the parameter
\*(lqcommand-line\*(rq.
To support executable shell scripts, the system ignores the first
line of a loaded script if it begins with #! followed by
a space or forward slash.
For example, the following script prints its command-line arguments.
.br
.sp
#! {InstallBin}/{InstallSchemeName} --script
.br
(for-each
.br
(lambda (x) (display x) (newline))
.br
(cdr (command-line)))
.SH RNRS TOP-LEVEL PROGRAMS
.LP
The \*(lq--program\*(rq option is like the \*(lq--script\*(rq option
except that the script file is treated as an RNRS top-level program.
The following RNRS top-level program prints its command-line arguments, as
with the script above.
.br
.sp
#! {InstallBin}/{InstallSchemeName} --program
.br
(import (rnrs))
.br
(for-each
.br
(lambda (x) (display x) (newline))
.br
(cdr (command-line)))
.LP
\*(lqscheme-script\*(rq may be used in place of \*(lqscheme --program\*(rq,
possibly prefixed by \*(lq/usr/bin/env\*(rq as suggested in the nonnormative
R6RS appendix on running top-level programs as scripts, i.e., the first line
of the top-level program may be replaced with the following.
.br
.sp
#! /usr/bin/env {InstallScriptName}
.br
.LP
If a top-level program depends on libraries other than those built into
\*s, the \*(lq--libdirs\*(rq option can be used to specify
which source and object directories to search.
Similarly, if a library upon which a top-level program depends has an
extension other than one of the standard extensions, the
\*(lq--libexts\*(rq option can be used to specify additional extensions
to search.
.LP
These options set the corresponding \*s parameters
library-directories and library-extensions.
The values of both parameters are lists of pairs of strings.
The first string in each library-directories pair identifies a
source-file root directory, and the second identifies the corresponding
object-file root directory.
Similarly, the first string in each library-extensions pair
identifies a source-file extension, and the second identifies the
corresponding object-file extension.
The full path of a library source or object file consists of the source or
object root followed by the components of the library name prefixed by
slashes, with the library extension added on the end.
For example, for root /usr/lib/scheme, library name
(app lib1), and extension .sls, the full path is
/usr/lib/scheme/app/lib1.sls.
.LP
The format of the arguments to \*(lq--libdirs\*(rq and
\*(lq--libexts\*(rq is the same:
a sequence of substrings separated by a single separator
character.
The separator character is a colon (:), except under Windows where it is a
semi-colon (;).
Between single separators, the source and object strings, if both are
specified, are separated by two separator characters.
If a single separator character appears at the end of the string,
the specified pairs are added to the existing list; otherwise, the
specified pairs replace the existing list.
The parameters are set after all boot files have been loaded.
.LP
If multiple \*(lq--libdirs\*(rq options appear, all but the final
one are ignored, and if
If multiple \*(lq--libexts\*(rq options appear, all but the final
are ignored.
If no \*(lq--libdirs\*(rq option appears and the CHEZSCHEMELIBDIRS
environment variable is set, the string value of CHEZSCHEMELIBDIRS is
treated as if it were specified by a \*(lq--libdirs\*(rq option.
Similarly, if no \*(lq--libexts\*(rq option appears and the CHEZSCHEMELIBEXTS
environment variable is set, the string value of CHEZSCHEMELIBEXTS is
treated as if it were specified by a \*(lq--libexts\*(rq option.
.LP
The library-directories and library-extensions
parameters set by these options are consulted by the expander when it
encounters an import for a library that has not previously been defined or
loaded.
The expander first constructs a partial name from the list of components in the
library name, e.g., \*(lqa/b\*(rq for library (a b).
It then searches for the partial name in each pair
of root directories, in order, trying each of the source extensions then
each of the object extensions in turn before moving onto the next pair of
root directories.
If the partial name is an absolute pathname, e.g., \*(lq~/.myappinit\*(rq
for a library named (~/.myappinit), only the specified absolute
path is searched, first with each source extension, then with each object
extension.
If the expander finds both a source file and its corresponding object
file, and the object file is not older than the source file, the
expander loads the object file.
If the object file does not exist, if the object file is older, or
if after loading the object file, the expander determines it was
built using a library or include file that has changed, the source
file is loaded or compiled, depending on the value of the parameter
compile-imported-libraries.
If compile-imported-libraries
is set to #t, the expander
compiles the library via compile-library (which is described below).
Otherwise, the expander loads the source file.
(Loading the source file actually causes the code to be compiled,
assuming the default value of current-eval, but the compiled
code is not saved to an object file.)
An exception is raised during this process if a
source or object file exists but is not readable or if an object
file cannot be created.
.LP
The search process used by the expander when processing an import
for a library that has not yet been loaded can be monitored by
setting the parameter import-notify to #t.
This parameter can be set from the command line via the
\*(lq--import-notify\*(rq command-line option.
.SH OPTIMIZE LEVELS
The \*(lq--optimize-level\*(rq option sets the initial value of the
\*s optimize-level parameter to 0, 1, 2, or 3.
The value is 0 by default.
.LP
At optimize-levels 0, 1, and 2, code generated by the compiler is
\fIsafe\fP, i.e., generates full type and bounds checks.
At optimize-level 3, code generated by the compiler is \fIunsafe\fP,
i.e., may omit these checks.
Unsafe code is usually faster, but optimize-level 3 should be used only
for well-tested code since the absence of type and bounds checks may
result in invalid memory references, corruption of the Scheme heap (which
may cause seemingly unrelated problems later), system crashes, or other
undesirable behaviors.
.LP
At present, there is no direct difference other than safety among
optimize levels.
.SH COMPILING FILES
.LP
\*s compiles source expressions as it sees them. In
order to speed loading of a large file, the file may be compiled
with the output placed in an object file.
(compile-file \*(lqfoo\*(rq) compiles the expressions in the file
\*(lqfoo.ss\*(rq and places the resulting object code on the file
\*(lqfoo.so\*(rq. Loading a pre-compiled file is no different from
loading the source file, except that loading is faster since
compilation is already done.
.LP
To compile a program to be run with --program, use
compile-program instead of compile-file.
compile-program preserves the first line unchanged, if it begins
with #! followed by a forward slash or space.
Also, while compile-file compresses the resulting object file,
compile-program does not do so if the #! line is present, so
it can be recognized by the shell's script executor.
Any libraries upon which the top-level program depends, other than
built-in libraries, must be compiled first via compile-file
or compile-library.
This can be done manually or by setting the parameter
compile-imported-libraries to #t before compiling the program.
.LP
To compile a script to be run with --script, use
compile-script instead of compile-file.
compile-script is like compile-program, but, like compile-file, implements
the interactive top-level semantics rather than the RNRS top-level
program semantics.
.SH BOOT and HEAP FILES
.LP
When \*s is run, it looks for one or more boot files to load.
Boot files contain the compiled Scheme code that implements most of
the Scheme system, including the interpreter, compiler, and most
libraries.
Boot files may be specified explicitly on the command
line via \*(lq-b\*(rq options or implicitly.
In the simplest case, no \*(lq-b\*(rq options
are given and the necessary boot files are loaded
automatically based on the name of the executable.
For example, if the executable name is \*(lqmyapp\*(rq, the
system looks for \*(lqmyapp.boot\*(rq in a set of standard
directories.
It also looks for and loads any subordinate boot files required
by \*(lqmyapp.boot\*(rq.
Subordinate boot files are also loaded automatically for the
first boot file explicitly specified via the command line.
When multiple boot files are specified via the command line and boot each
file must be listed before those that depend upon it.
.LP
The \*(lq--verbose\*(rq option may be used to trace the boot file
searching process and must appear before any boot arguments
for which search tracing is desired.
.LP
Ordinarily, the search for boot files is limited to a set of
default installation directories, but this may be overridden by setting
the environment variable SCHEMEHEAPDIRS.
SCHEMEHEAPDIRS should be a colon-separated list of directories, listed in
the order in which they should be searched.
Within each directory, the two-character escape sequence \*(lq%v\*(rq
is replaced by the current version, and the two-character escape sequence
\*(lq%m\*(rq is replaced by the machine type.
A percent followed by any other character is replaced by the second
character; in particular, \*(lq%%\*(rq is replaced by \*(lq%\*(rq, and
\*(lq%:\*(rq is replaced by \*(lq:\*(rq.
If SCHEMEHEAPDIRS ends in a non-escaped colon, the default directories are
searched after those in SCHEMEHEAPDIRS; otherwise, only those listed in
SCHEMEHEAPDIRS are searched.
Under Windows, semi-colons are used in place of colons.
.LP
Boot files consist of a header followed by ordinary compiled code and
may be created with make-boot-file.
For example,
.br
.sp
(make-boot-file "myapp.boot" '("petite")
"myapp1.so" "myapp2.so")
.sp
.br
creates a boot file containing the code from myapp1.so and myapp2.so
with a header identifying petite.boot as a boot file upon which the new
boot file depends.
Source files can be provided as well and are compiled on-the-fly
by make-boot-header.
.LP
Multiple alternatives for the boot file upon which the new boot
file depends can be listed, e.g.:
.br
.sp
(make-boot-file "myapp.boot" '("petite" "scheme")
"myapp1.so" "myapp2.so")
.sp
.br
When possible, both \*(lqscheme\*(lq and \*(lqpetite\*(lq should be
specified when creating a boot file for an application, as shown above, so
that the application can run in either \*p or \*s.
If the application requires the use of the compiler, just
\*(lqscheme\*(lq should be specified.
.LP
If the new boot file is to be a base boot file, i.e., one that does not
depend on another boot file, petite.boot (or some other boot file created
from petite.boot) should be listed first among the input files.
.br
.sp
(make-boot-file "myapp.boot" '() "petite.boot"
"myapp1.so" "myapp2.so")
.sp
.br
.SH DOCUMENTATION
.LP
Complete documentation for \*s is available in two parts:
\fIThe Scheme Programming Language, 4th Edition\fP, and
\fIThe Chez Scheme Version 9 User's Guide\fP.
The first document is available in printed form from MIT Press,
and links to online versions of both documents are available
at https://cisco.github.io/ChezScheme/.
.LP
Several example Scheme programs, ranging from a simple factorial procedure
to a somewhat complex unification algorithm, are in the examples directory
(see FILES below). Looking at and trying out example programs is a good way
to start learning Scheme.
.SH ENVIRONMENT
.LP
The environment variable
.B SCHEMEHEAPDIRS \fR
(see above) may be set
to a colon-separated (semi-colon under Windows) list of directories
in which to search for boot files.
.SH FILES
.if 0 COMMENT: put the longest path from below in the tab computation:
.ta \w'{InstallLibExamples}'u+.25i
{InstallBin}/{InstallSchemeName} executable file
.br
{InstallBin}/{InstallPetiteName} executable file
.br
{InstallBin}/{InstallScriptName} executable file
.br
{InstallLibExamples} example program library
.br
{InstallLibBin} boot and include files
.sp
.br
.SH SEE ALSO
.in +5
.br
.ti -5
R. Kent Dybvig,
\fIThe Scheme Programming Language, 4th Edition\fP,
MIT Press (2009), http://www.scheme.com/tspl4/.
.br
.ti -5
\fIChez Scheme Version 9 User's Guide\fP,
Cisco Systems, Inc.
.br
.ti -5
Michael Sperber, R. Kent Dybvig, Matthew Flatt, and Anton van Straaten, eds.,
.if t \*(lqRevised\u6\d Report on the Algorithmic Language Scheme,\*(rq
.if n \*(lqRevised^6 Report on the Algorithmic Language Scheme,\*(rq
(2007), http://www.r6rs.org/.
.br
.ti -5
Daniel P. Friedman and Matthias Felleisen,
\fIThe Little Schemer\fP, fourth edition,
MIT Press (1996).
.br
.ti -5
Harold Abelson and Gerald J. Sussman with Julie Sussman,
\fIStructure and Interpretation of Computer Programs,
Second Edition\fP,
MIT press (1996).
.in -5
.SH AUTHOR
Copyright 2019 Cisco Systems, Inc.
Licensed under the Apache License, Version 2.0
(http://www.apache.org/licenses/LICENSE-2.0)