
This is the change log of the original version of S9fES.
See the HISTORY file for more recent changes.

2018-08-23
	Fix: Null vector constant was unprotected from GC. (s9core.c)
2018-08-19
	The S9 interpreter failed to recover from error conditions
	because of a missing s9_reset() call. (s9.c)
	Upgraded S9core to Mk IIIe. (s9core.*)
2018-08-18
	Rolled back changes of 2018-07-22. INEXACT->EXACT of a real number
	with a non-zero fractional part is an error. Use ROUND in combination
	with INEXACT->EXACT if that is what you intend. (s9.c, s9.scm)
	Removed ROUND primitive. (s9.c)
	Removed REAL_ROUND() function (it's better done in Scheme). (s9core.c)
2018-08-01
	Fix: -u command line option caused an infinite loop. (s9.c)
	So nobody ever uses this option? :)
2018-07-22
	INEXACT->EXACT now returns an integer even if its argument has
	fractional digits, e.g. (inexact->exact 1.5) ==> 2. (s9.c)
2018-07-21
	Strings returned by SYMBOL->STRING are now immutable, as specified
	in R4RS, section 3.5. (s9.c)
	Upgraded S9core to Mk IIId. (s9core.*)
	Added s9_real_round() function. (s9core.*)
	Made ROUND a primitive function. (s9.c)
2018-06-05
	Fix: LOADing a file with any missing closing parentheses did not
	cause an error. (Removed some left-over code from reader.)
2017-11-09
	Merged Plan 9 patches by McKay Marston. Thanks!
	Upgrade to S9core Mk IIIc. (s9core.*)
	Changed S9core documentation format from PDF to ASCII. (s9core.txt)
2017-01-25
	Made CSV:READ translate subsequent commas as empty fields, e.g.:
	(csv:read)"",,"" ==> ("" "" ""). (ext/csv)
	Added CSV:READ and CSV:WRITE help pages. (help/csv/)
2017-01-24
	Added CSV (comma-separated values) extension containing CSV:READ
	and CSV:WRITE primitives. (ext/csv/)
2016-12-06
	Fix: S9SOS mis-computed the precedence order for multi-methods.
	Patch supplied by David Person, thank you!
2016-11-30
	Upgrade to S9core Mk III. (s9core.*)
	s9_make_integer() will now return pre-allocated objects for some
	common values (0, 1, 2, 10). (Thanks, David Person!)
	Added type_tag() accessor.
2016-08-23
	The LENGTH fix of 2014-12-06 got reverted somewhere along the way.
	Re-fixed. (s9.c)
2016-08-05
	Upgrade to S9core Mk II. (s9.c, s9*.h)
	Added -e (eval) and -r (run) command line arguments. (s9.c)
2015-11-19
	real_ceil(), real_floor(), real_trunc() could fail when being
	passed an integer. Thanks, Alexander Shendi! (s9core.c)
2015-11-17
	Added real_power() function to s9core, added EXPT primitive
	(unused, though; the Scheme version is faster). (s9core.[ch])
2015-11-08
	S9core: added the open_input_string(), close_input_string(),
	and port_eof() functions. (s9core.[ch])
	S9core: fixed some function types (mostly port-related), made
	readc() and reject() functions (previously macros). (s9core.[ch])
	Updated the S9core manual. (s9core.tr)
	Fixed a potential GC leak in string_to_bignum(). (s9core.c)
2015-08-10
	Fix: S9core: make_vector() overwrote unallocated memory. (s9core.c)
	(This bug did *not* affect the S9 interpreter!)
2015-07-14
	Made APROPOS find extension procedures. (contrib/)
2015-07-13
	Adapted S9HELP to the new help folder structure. (prog/)
	Renamed extension directories to reflect their names:
	ext/unix --> ext/sys-unix, ext/plan9 --> ext/sys-plan9.
	Modified install scripts for new help structure.
2015-07-12
	Renamed NETWORK extension to NET-UNIX. (ext/unix/)
	Moved portable procedures from ext/ to lib/.
	Re-structured help folder: moved extension procedures to separate
	directories. (help/)
	Made HELP find only procedures of extensions that are actually
	available. (contrib/)
2015-07-09
	Added add_image_vars() function to S9core. (s9core.*)
	Cleaned up S9 bignum <-> C int conversion. (ext/plan9/)
	Fixed some bugs in sys_convD2M(). (ext/plan9/)
	Added DIR structure to Plan 9 extension. (ext/plan9/)
2015-07-07
	Imported Bakul Shah's Plan 9 extension. (ext/plan9/) Cool! Thanks!
	Restructured the extensions directory:
		* ext/ -- portable extensions (might even move to lib/)
		* ext/unix, ext/plan9 -- OS-specific extensions
		* ext/curses -- curses extension
2015-07-06
	Fix: internal counters did not count trillions correctly. (s9core.c)
	Thanks, Arun Srinivasan!
2015-07-01
	Changed Plan 9 install procedure to allow for multi-platform
	installation. (mkfile, util/)
	Added *HOST-SYSTEM* to help pages. (help/)
2015-06-30
	Added install target for Plan 9. (mkfile)
	Fix: embedded newline in a string literal would not bump the line
	counter. (s9.c) Thanks, David Person!
2015-06-29
	Added *HOST-SYSTEM* variable. (s9.c)
	Made HELP print without prompting on Plan 9. (contrib/)
	Added Plan 9 installation procedure.
2015-06-28
	Rewrote signal handling to use notify()/noted() on Plan 9. (s9.c)

-------------------------------------------------------------------------------
	Interface change: S9core PRINT is now called PRINTS; see below.
-------------------------------------------------------------------------------

2015-06-27
	Renamed print() function of S9core to prints(). Sorry about the
	inconvenience; "print" is reserved in the Plan 9 C library.
	Fixed some Plan 9 issues (signal handlers, function declarations,
	mkfile). (s9.c, s9core.c)
	C2HTML: fixed missing  after keyword at end of file. (contrib/)
2015-06-23
	Removed TRACE help page and entry in *S9FES-PROCEDURES*.
	Fix: added MACRO-EXPAND and MACRO-EXPAND-1 (had been removed
	accidentally). (s9.c) Thanks, nullbuilt0! (reddit)
2015-06-18
	Fix: (expt 0 r) ==> 0 for r > 0. (s9.scm)
	Added regression tests. (util/)
2015-06-17
	Fix: Added missing POSIX/XOPEN prelude to Unix extension (required
	on Linux, Cygwin, etc). (ext/)
2015-06-15b
	Extended magic ID length to 16 bytes. (S9core)
	Included time stamp in magic ID. (s9.c)
	Fixed (expt 0 r) where r is not integer. (s9.scm)
2015-06-15
	General:
		- Factored out the S9core, providing a library for
		  implementing dynamic languages. Discussed in s9core.pdf.
		- Real number arithmetics are now a non-optional part of
		  the interpreter.
	Policy changes:
		- Images are preferred over source files on startup, i.e.
		  first all directories of *LIBRARY-PATH* are searched for
		  images, then all directories are searched for source files.
		  The old policy was to load the first image /or/ source
		  from the first directory containing either of those.
		- Existing output files are silently overwritten by
		  the OPEN-OUTPUT-FILE, WITH-OUTPUT-TO-FILE, and
		  WITH-OUTPUT-FILE functions. Previous policy was to signal
		  an error.
		- The S9:S9 procedure will be called last when initializing
		  extensions thereby allowing it to call procedures of
		  other extensions. (Previously, S9:S9 was called first.)
	Additions:
		- The *ARGUMENTS* variable binds to a list of strings
		  containing the command line arguments passed to the
		  /program/ (not to the interpreter), i.e. the ARGS in
		  "-f program args".
	Command line options:
		- The -f flag is now optional, i.e. "s9 -f file args" and
		  "s9 file args" do the same.
		- The "-m size" flag has been split into "-k size" (vectors)
		  and "-n size" (nodes).
		- "-u" is short for "-k 0 -n 0" (unlimited space).
		- "-n" no longer means "do not load rc file".
	Removals:
		- S9 no longer loads an rc file (~/.s9fes/rc) on startup.
		  Use the image file and the (badly documented) S9:S9
		  procedure to do things on start-up.
		- Dropped the "-t count" command line option. The five most
		  recently called procedures will print in error messages.
		- Dropped "imprecise" digits ("#") from number format. Use
		  "5" instead, that's what it did anyway.
		- Dropped the TRACE command.
		- Dropped the DUMP-IMAGE procedure. (Use -d)

-------------------------------------------------------------------------------
	S9core Refactoring
-------------------------------------------------------------------------------

2015-06-08
	Fix: (lambda (x) ...) and (define (x) ...) would attempt to
	macro-expand (x). Thanks, David Person!
	Note: this still fails in (cond (x)). Rename X as a work-around.
2015-03-31
	Added statistics functions: CDF, ERF, MEAN, MEDIAN, MODE, NDF,
	QUARTILE, RANGE, STDDEV, VARIANCE. (lib/)
2015-03-13
	Added constants (S_zero, ...) for frequently used bignum literals,
	so we don't have to call make_integer() each time. (s9.c, s9-real.c)
2015-03-12
	Fix: TRACE without arguments could core-dump on some machines. (s9.c)
	Thanks, David Person!
	Made real number division round its mantissa instead of truncating
	it, e.g.: (/ 2 3) --> 0.66...67 instead of 0.66...66. Should improve
	real number precision a bit. (s9-real.c) Suggested by David.
2015-03-10
	Fix: These functions would not terminate for certain values due to
	inappropriate real number comparison: EXP, LOG, COS, SIN, TAN, ATAN,
	SQRT. Thanks to David Person for pointing this out! (s9-real.scm)
	Introduced *EPSILON* constant representing the least real number
	with a precise representation. (s9.c)
2014-12-16
	Simplified print_symbol() procedure. (s9.c)
2014-12-13
	Fixed ATAN function for negative arguments. (s9-real.scm)
	Thanks again, David!
	Added some #ifdefs to guess whether we are compiling on a
	64-bit system. (s9.h)
2014-12-06
	Fix: LENGTH would print garbage when reporting an improper list.
	(s9.c) Thanks, David Person!
2014-11-26
	Added new Plan 9 mkfile and straightened out the build process
	on non-Unix systems. Thanks, Ray Lai!
2014-11-25
	Modified util/libtest.sh to not include the Unix extension tests
	when the Unix extension is not present.
2014-11-24
	Fix: replaced atol() with internal version to work around Plan 9
	atol()'s behavior (leading '0' means octal). (s9.c, s9-real.c)
2014-11-05
	Fixed SPAWN-COMMAND help page. (ext/, help/)
2014-11-03
	Fixed some warnings in util/rpp.c (not used outside of build).
2014-10-31
	Fixed a few potential GC leaks. (s9.c, s9-real.c)
2014-08-08
	Changed hash function. (s9.c)
2014-08-04
	Fix: wrong magic number in 64-bit image check. (s9.c)
2014-08-03
	Missing help link: REAL? (help/, util/)
2014-07-25
	Fix: MAKE-MATCHER accidentally redefined CASE using an equivalent
	but less efficient version. (lib/)
2014-07-21
	Simplified LET* (s9.scm)
2014-07-18
	Made LENGTH and LIST-TAIL use integers internally. (s9.c)
2014-07-17
	Made the fatal error handler print "fatal " to stderr when running
	in batch mode. (s9.c)
2014-07-16
	Added the "99 bottles" example (using SYNTAX-RULES). (contrib/)
2014-07-12
	Fix: STRING->SYMBOL, SYMBOL->STRING, STRING-APPEND and STRING-COPY
	work on counted strings now. (s9.c)
	Fixed embarassing crash when reporting type errors, introduced
	four days ago when changing the primitive procedure representation.
	(s9.c)
2014-07-11
	Applied some small cosmetical fixes. (s9.c)
2014-07-10
	Renamed symbols beginning with an underscore for increased
	portability. (s9.c, s9.h, s9-real.c)
2014-07-09
	Removed binary ID from magic header, added number of primitives
	instead. (s9.c)
2014-07-08
	Made the reader report the location where an delimited list
	started. (s9.c)
	Invented a new method for storing primitive procedures in images
	in a way that cooperates well with ASLR and PIC. (s9.c)
2014-06-29
	Made APROPOS (and ,a) return _all_ procedures, even those not
	currently loaded. (contrib/)
	Patch from http://github.com/barak/scheme9: intercept file read
	errors when reading an image file. Thanks, Barak! (s9.c)
	Added and documented EVAL procedure. (s9.c)
2014-06-27
	Made EDOC source code a better example of EDOC.
	(prog/edoc.scm.edoc)
2014-06-25
	Removed S9E, the S9 Editor, because it was broken. (contrib/)
2014-05-30
	Fixed some bogus warnings generated by Clang.
2014-01-11
	Added clarifying coment in lookup(). (s9.c)
	Fixed typo in man page. Thanks, Yi Dai (s9.1)
2013-11-26
	Added ARGV primitive to core system. See below. (s9.c)
2013-11-24
	Added ENVIRON and SYSTEM primitives to the core interpreter. (s9.c)
	Mostly to use minimal S9 in web programming.
2013-04-10
	Added a workaround for plan9's atol() function, which
	interprets leading '0' as octal. Thanks, Bakul Shah! (s9.c)
2013-02-09
	Fix: FORMAT-TIME emitted wrong month name with ~@m. Thanks,
	Doug Currie! (ext/)
2013-01-22
	Fix: S9E would abort when exiting from the [^L][e] prompt using
	backspace. (contrib/)
2013-01-17
	Added COLLECT procedure. (lib/)
2013-01-14
	Fix: SYNTAX-RULES could abort while matching an ellipsis against
	an atom. (lib/)
2013-01-09
	S9E: Fixed highlighting of marked regions in side-scrolled lines.
	(contrib/)
2013-01-02
	Added experimental "hard" cutting (TRY/CUT) to AMK. (lib/)
	Added the N-Queens program (using AMK). (contrib/)
2012-12-26
	Added numeric goals to AMK. (lib/)
2012-12-22
	More changes to AMK for compatibility with the upcoming version
	of the book. (lib/)
2012-12-20
	Made AMK always return () or (()) when no variable was given
	in RUN*. (lib/)
2012-12-17
	Added color customization to S9E. (contrib/)
2012-12-12
	Cleaned up AMK, made it more compatible with the book. (lib/)
	Fix: REM-PROP reversed its property list argument. (lib/)
2012-12-10
	Finished S9E, the new S9 Editor with integrated REPL buffer.
	(contrib/)
2012-12-05
	Made DEFINE-MACRO an alias of DEFINE-SYNTAX. (s9.c)
2012-12-02
	Fix: GENSYM had a potential race condition resulting in a wrong
	prefix. (s9.c)
	Checked for similar race conditions due to string/vector pool
	compaction; seems clean.
2012-11-30
	Fix: SUBSTRING had a GC race condition, which could result in
	the extraction of garbage. (s9.c)
2012-11-27
	Added SRFI-43-compliant VECTOR-COPY and VECTOR-APPEND primitives.
	(s9.c, s9.scm)
2012-11-26
	Fix: REM-PROP failed to remove properties from empty lists. (lib/)
	Removed SYS:LCHOWN and SYS:LUTIMES system calls. Caused only
	portability issues. (ext/)
2012-11-25
	Added S9SYMBOLS program (dump symbols from help pages). (prog/)
2012-11-24
	Added "-i -" (don't load heap image) option. (s9.c)
2012-11-18
	Added color support to GET-LINE. (ext/)
	Added more key codes to GET-LINE. (ext/)
2012-11-15
	Added CURS:KEY-DC (delete-char key), CURS:KEY-IC (insert-char key),
	and CURS:KEY-END constants. (ext/)
2012-11-14
	Fix: swapped fore/background arguments of CURS:COLOR-SET. (ext/)
2012-11-13
	Fix: PACKAGE was lacking an import of FILTER. (lib/)
	Fix: test process created wrong image file. (util/)
	Thanks, Doug Currie!
2012-11-12
	Added color support to the curses extension. (ext/)
	Added the CURS:COLOR-SET and CURS:HAS-COLORS primitives. (ext/)
	Updated the help pages.
2012-11-11
	Simplified creation of top-level bindings. (s9.c, s9.h)
	Removed SYNTAX? predicate. (s9.c)
	Added -P (prolog) and -E (epilog) options to EDOC. (prog/)
	Changed web color scheme. (util/)
2012-11-09
	Factored out CHAR-PLOT from RUNTIME-STATS. (ext/, lib/)
	Made CHAR-CANVAS a package. (lib/)
	Made RUNTIME-STATS a package. (ext/)
2012-11-08
	Made IOTA accept a second argument. (lib/)
	Added the CHOOSE procedure. (lib/)
	Added the CURRYR (curry-right) macro. (lib/)
2012-11-07
	Made GENSYM accept a symbolic argument. (s9.c)
2012-11-04
	Added extra LDFLAGS for OSX. Thanks, Doug Currie!
	Fix: (lambda x ...) did not work in SYNTAX-RULES. (lib/)
2012-11-02
	Fixed a potential memory leak in SYS:EXECVE. (ext/)
	Made (the still broken) SYNTAX-RULES alpha-rename variables
	of named LET and DO. (lib/)
2012-11-01
	Added LIST-COPY and TAKE procedures. (lib/)
	Renamed GROUP-LIST to GROUP, swapped arguments to be more
	consistent with other list procedures. (lib/)
	Reverted EQUAL? to comparing vectors by converting them
	to lists first. (s9.c)
2012-10-30
	Renamed QUEUE and UNQUEUE to QUEUE! and UNQUEUE!. (lib/)
	Updated help pages.
	Cleaned up cooperative threads procedures and fixed last thread
	exit problem. (lib/)
	Made the interpreter reset the TTY when exiting after an error.
	(s9.c)
	Added more EQUAL? tests. (util/)
2012-10-27
	Added a SIGTERM handler to reset the TTY when curses support
	is compiled in. (s9.c)
2012-10-22
	Optimized DRAW-TREE. (contrib/)
2012-10-21
	Cleaned up DRAW-TREE code. (contrib/)
2012-10-19
	Fixed order of assignment in FLUID-LET. (lib/)
2012-10-17
	Made IOTA a single-argument procedure. (lib/)
	Renamed IMPORT keyword of simple-modules to USING. (lib/)
2012-10-16
	Fix: SCM2HTML did not reset color after comments in quoted
	objects in string-input mode. (s9.c)
2012-10-14
	Suppressed trailing blanks when stopping run-away output. (s9.c)
	Fixes bounds checking in multi-dimensional ARRAYs. (lib/)
2012-10-13
	Fix: NUMBER->STRING would suppress trailing zeroes in expanded
	real numbers. E.g.: (number->string 1.23e5) ==> "123". Oops!
	(s9-real.scm)
2012-10-11
	Made SCM2HTML accept upper case # syntax, e.g.: #F. (contrib/)
2012-10-11
	Made BIT-OP variadic. (s9.c)
	Added BIT-OP operations 16 (shift left) and 17 (shift right). (s9.c)
2012-10-10
	Made EQUAL? cons-free when comparing vectors. (s9.scm)
2012-10-09
	Made the reader and printer abort processing of suspiciously
	deeply nested lists and vectors. Thanks to dig1 and bsamograd
	on reddit! (s9.c, s9.h)
	Made EDOC generate back links only in level-0 headings. (prog/)
2012-10-05
	Now accepting [...] as an alias of (...). (s9.c)
	Updated SCM2HTML to handle [...] properly. (contrib/)
	Updated test suite. (util/)
	Fix: STANDARD-ERROR-PORT was documented as STANDARD-ERROR. (help/)
2012-10-04
	Fix: error reporting was broken by interruptible printer. (s9.c)
2012-10-03
	Made WRITE and DISPLAY primitives interruptible. (s9.c)
	Passed help files through spell-checker.
	(lib/, contrib/, prog/, help/, edoc/)
2012-10-02
	Added "variable index" command to EDOC. (prog/)
	Added REAL type to TYPE-OF and TYPE-CASE. (lib/)
2012-09-29
	Added "non-printing index" command to EDOC. (prog/)
2012-09-25
	Added "unreadable" syntax (#<foo>) to SCM2HTML. (contrib/)
2012-09-24
	Fixed quotation in SCM2HTML. (contrib/)
	Added -t (tilde-quotes) flag to SCM2HTML1. (prog/)
2012-09-22
	Added style for invisibly quoted forms to SCM2HTML. (contrib)
2012-09-21
	Added the TILDE-QUOTES option to SCM2HTML. (contrib/)
	Made EDOC pass 'TILDE-QUOTES: #T to SCM2HTML. (prog/)
2012-07-09
	Changed webdump color scheme. (util/)
	Adapted web theme to current home page. (util/)
	Updated the man page. (s9.1)
	Misc. cosmetical changes. (lib/)
2012-07-08
	Renamed SOS to S9SOS - S9 Simple Object System. (contrib/)
	Replaced the '!image' option by '-i image'. (s9.c)
	Allowed to specify an image source file with '-i'; made the
	LIBRARY option obsolete. (s9.c)
	Cleaned up some meta files.
2012-07-06
	Fixed more typos.
2012-07-05
	Removed the ARSE development environment, because it has a
	design bug that makes it crash when undoing changes near the
	top or bottom of a file.
	Fixed a few typos.
	Fix: BIT-OP could overflow on 64-bit systems. (s9.c)
2011-05-11
	Cleaned up the Unix/POSIX/XOPEN Mambo Jambo prelude. (s9.h)
	Added some casts to make later GCCs happy. (s9.c, s9-real.c)
	(unreleased.)
2010-11-13
	Fix: sudden allocation of large vectors failed, even if enough
	vector space was present (this did not happen when allocating
	lots of small vectors, releasing them, and then allocating a
	large vector). (s9.c)
2010-10-29
	Fix: missing hash-table reference in memoize.scm. (lib/)
2010-10-11
	Added GET-PROP, PUT-PROP, etc. (lib/)
2010-10-08
	Added STRING-PREFIX=? and STRING-PREFIX-CI=? procedures. (lib/)
2010-10-07
	Fix: MAKE-STRING and MAKE-VECTOR did not check for negative
	arguments. (s9.c)
2010-10-06
	Added TIME-ADD, TIME-SUBTRACT, TIME-DIFFERENCE, TIME-BEFORE?,
	and TIME-AFTER? procedures. (lib/)
	Moved SWAP! to "setters.scm"; removed "swapb.scm". (lib/)
2010-10-05
	Added small-magnitude bit operators (bitops). (lib/)
2010-10-04
	Renamed BITWISE-AND-NOT --> BITWISE-NOT-AND,
	        BITWISE-OR-NOT  --> BITWISE-NOT-OR,
	        BITWISE-XOR-NOT --> BITWISE-NOT-XOR. (lib/)
	Added fast bit operations (BIT-OP). (s9.c)
2010-10-03
	Misc. minor changes. This is the book version.
2010-09-29
	Applied minor change to RIB internal structure. (s9.c)
2010-09-27
	Added \i (image) mode to EDOC. (prog/)
2010-09-23
	Added "NIL" and "@ rest" syntax to MAKE-MATCHER. (lib/)
2010-09-22
	Added line concatenation via \\ to EDOC, made EDOC's -b
	option link to a file given on the command line instead of
	hardwiring "index.html". (prog/)
2010-09-21
	Changed MAKE-MATCHER semantics. Once again. :-/ But this
	time it will be final! (lib/)
	Moved the MAKE-MATCHER code to the EDOC section. (lib/, edoc/)
2010-09-19
	Re-organized the "primitives" section. (s9.c)
2010-09-16
	Moved SYNTAX-RULES to EDOC section. (lib/, edoc/)
2010-09-13
	EDOC: Improved layout of Lout output; still experimental,
	though! (prog/)
2010-09-11
	Fixed some minor 64-bit/prototyping glitches. (s9*.c)
2010-09-10
	Added HTMLIFY-CHAR and LOUTIFY-CHAR to library. (lib/)
	Started Lout backend in EDOC. (prog/)
2010-09-09
	EDOC: improved error messages, implemented strict mode
	(being picky about matching braces). (prog/)
2010-09-07
	Fixed botched optimization in EXP function. (s9-real.scm)
2010-09-06
	Cleaned up real number primitives. (s9-real.c)
2010-09-05
	DISPLAY/WRITE now round the last digit of real numbers with
	large mantissas, so 1.99999999999999997 actually prints as
	2.0 on 32-bit systems. (s9-real.scm)
	Added INC!, DEC!, and SET-VARS! syntax. (lib/)
2010-09-04
	Factored out CHECK-BINDINGS and SPLIT-BINDINGS in the Scheme
	core. (s9.scm)
	Fix: a quotation char ('`,) followed by a closing paren swallowed
	that closing paren. (s9.c)
2010-09-03
	Fix: APPEND accepted atoms in positions other than the last. (s9.scm)
	PRETTY-PRINT now prints (and), (or), and (begin) more nicely.
	(contrib/)
2010-09-02
	Allowed nested quasiquotation as long as an embedded QUASIQUOTE
	is inside of UNQUOTE or UNQUOTE-SPLICING. (s9.scm)
	Applied more optimizations to MAKE-MATCHER. (lib/)
	Added GROUP-LIST procedure to library. (lib/)
	Fix: WITH-OUTPUT-TO-FILE always returned #<unspecific>. (s9.scm)
2010-09-01
	Made STRING and VECTOR primitives. (s9.c)
	Fix: SYS:READLINK did not NUL-terminate its return string. (ext/)
	Optimized internal accessors of MAKE-MATCHER. (lib/)
2010-08-31
	Changed PACKAGE syntax and semantics. (lib/)
	Added Red-Black Trees. (lib/)
	Various small changes. (s9.c)
2010-08-29
	Changed MAKE-MATCHER syntax. (lib/)
	Retired ML-MATCH syntax. (lib/)
2010-08-26
	Applied various cosmetics and micro-optimizations. (s9.c)
2010-08-25
	Changed environment box model from (name . (value)) to
	(name . value), (ab?)using the CDR field as a box. This
	saves quite a few conses during evaluation. (s9.c)
	Improved syntax checking in local DEFINEs. (s9.c)
	Added detection of improper lists (syntax errors) in
	special forms. (s9.c)
2010-08-24
	Made STATS primitive expand macros before evaluation. (s9.c)
2010-08-22
	Fix: Made EXPT return an inexact number when passed an inexact
	argument, because conversion lost digits. Also made SQRT return
	an inexact result. (s9-real.scm)
2010-08-20
	Documented EDOC using EDOC. (prog/)
	Fix: counting newlines in block comments. (s9.c)
2010-08-19
	SCM2HTML: added support for block comments. (s9.c)
2010-08-15
	Fix: all real numbers must be inexact according to R4RS. (s9.c)
	Fixed a precision bug in mixed bignum/real operations. (s9-real.c)
	Fixed missing trailing zero in (number->string 1.0). (s9-real.scm)
2010-08-14
	Cleaned up SCM2HTML program. (contrib/)
	Added C2HTML program. (contrib/)
2010-08-13
	Changed interface of SCM2HTML and moved it to contrib/.
	Added SCM2HTML1 program (SCM2HTML wrapper). (prog/)
	Fix: (+ 0.0 -1.0e-999999999) gave 0.0. (s9-real.c)
	Fix: (+ #e0.0 #e1.0e-999999999) gave an inexact result. (s9-real.c)
2010-08-12
	ARSE: made [d][/]x and [d][?]x repeatable. (contrib/)
	Added ,q (sys:exit) meta command. (s9.c)
	Added #| ... |# comments. (s9.c)
2010-08-10
	Tweaked real number interface (internal). (s9*.[ch])
	Updated the man page. (s9.1)
2010-08-09
	Finished integration of big real number support. (*.c, *.scm)
2010-08-08
	Re-integrated big real arithmetics. (*.[ch], *.scm)
	Added real number test suite. (util/)
2010-08-07
	Added make-cats.scm program and CATEGORIES.html file. (util/)
2010-08-06
	ARSE: fix: clear undo log when loading a different file
	into an edit buffer. (contrib/)
2010-08-03
	Fix: (,x) was interpreted as a meta command. (s9.c)
	Fix: SYNTAX-RULES failed to detect some syntax errors
	before ellipses. (lib/)
	S9 SOS: make <built-in> instantiation invalid. (contrib/)
	Added 'COMPRESS: option to RUNTIME-STATS. (ext/)
2010-08-02
	Applied some cosmetics to SYNTAX-RULES. (lib/)
	Added LISTQ syntax. (lib/)
	Made APPEND fold to the right (O(n) instead of (O(n^c)
	when appending multiple lists). (s9.scm)
	Added COLS program. (prog/)
2010-08-01
	CHAR-CANVAS: auto-clipping out-of-range coordinates. (lib/)
	RUNTIME-STATS: misc. small fixes. (ext/)
2010-07-31
	Added plotter and table formatter to RUNTIME-STATS. (ext/)
	Fixed CANVAS-PLOT-LINE. (lib/)
2010-07-30
	Added the RUNTIME-STATS procedure to library. (ext/)
	Added SWAP! syntax to library. (lib/)
	Added character-based canvas to library. (lib/)
2010-07-29
	Made STATS return a list instead of printing its data. (s9.c)
	Added SYS:GETTIMEOFDAY extension procedure. (ext/)
	Added TIME procedure to library. (/ext)
	Fixed S9 SOS built-in hierarchy. (contrib/)
2010-07-28
	Added meta commands, which are entered by typing a #\,
	at the top level and without any enclosing parens. See
	S9(1) for details. (s9.c)
2010-07-27
	Added PUSH! and POP! macros. (lib/)
	Added PACKAGE macro. (lib/)
2010-07-26
	Removed UNDEFINED primitive; causes only trouble. (s9.c)
	Added minor optimizations to MAKE-MATCHER. (lib/)
	Made MAKE-MATCHER and ML-MATCH two separate packages. (lib/)
2010-07-25
	Made S9 not count initial GC in STATS. (s9.c)
	Added cons cell statistics to interpreter. (s9.c)
	Fix: SYNTAX-RULES failed to expand stuff following "...". (lib/)
2010-07-24
	Added TREE-MAP procedure. (lib/)
	Fix: RE-MATCH returned wrong format when processing
	REs beginning with "^" in combination with 'ALL. (lib/)
2010-07-23
	Finished the S9 SOS and its documentation. (contrib/)
2010-07-21
	Made ":set regex" default in ARSE. (contrib/)
2010-07-20
	Bootstrapped SOS. (contrib/)
2010-07-19
	ARSE: removing output that begins with ";" when reloading
	a buffer. (lib/)
2010-07-18
	Added first sketch of SOS (Scheme Object System). (contrib/)
	Added 'REVERSE keyword to T-SORT; added T-SORT-NET. (lib/)
	Added 'TOP-DOWN option to T-SORT. (lib/)
	ARSE: added "scheme-init" option. (contrib/)
2010-07-17
	Added 'CONVERT-UNREADABLE option to READ-FROM-STRING. (lib/)
	Added help pages for the REVERSE!, STATS, SYNTAX?, TRACE, VOID,
	and UNDEFINED procedures. (help/)
2010-07-16
	Added UNDEFINED procedure; see s9(1). (s9.c)
2010-07-15
	Added KEYWORD-VALUE procedure. (lib/)
	Rewrote HASH-TABLE, added support for 'SIZE and 'TEST keywords.
	(lib/)
	Added WHEN, UNLESS, WHILE, and UNTIL syntax. (lib/)
	ARSE: made [TAB] insert blanks when not typing a symbol. (contrib/)
2010-07-14
	Added DUPLICATES procedure and friends. (lib/)
	DEFINE-STRUCTURE not reports duplicate slot names. (lib/)
2010-07-13
	Added queue data type. (lib/)
2010-07-12
	Added MEMOIZE procedure and DEFINE-MEMOIZED syntax. (lib/)
2010-07-11
	Added ID (identity) procedure. (lib/)
	ARSE: added regex support to [/] and [?] commands. (contrib/)
	Re-organized library. (lib/)
	Added check-descr.scm to check descriptions for web dump. (util/)
2010-07-10
	Added SPLIT and MERGE procedures, rewrote MERGESORT. (lib/)
	Fixed stuck state (0) in RANDOM-STATE. (lib/)
	Fix: SYS:MAKE-INPUT-PORT and SYS:MAKE-OUTPUT-PORT
	could return a closed port due to GC. (ext/)
	Rewrote BITWISE-... operators. (lib/)
	Added INTEGER->BINARY-STRING and BINARY-STRING->INTEGER. (lib/)
	Fix: RE-SUBST generated wrong matches with trailing "\\)". (lib/)
2010-07-09
	ARSE: fixed spurious trailing lines after undo. (contrib/)
	ARSE: added regular expression support (:s). (contrib/)
	Added COMPOSE, COMPLEMENT, TRUE, and FALSE procedures. (lib/)
	Added RANDOM and RANDOM-STATE procedures. (lib/)
2010-07-08
	Added SYNTAX? primitive. (s9.c)
	Added T-SORT (topological sort) procedure. (lib/)
	Added EQUAL-CI? procedure. (lib/)
	Added TYPE-OF procedure and TYPE-CASE syntax. (lib/)
	Added ASSP and MEMP procedures. (lib/)
	Applied various small fixes to PRETTY-PRINT. (contrib/)
	Updated man page. (s9.1)
2010-07-07
	Added RE-SUBST procedure to REGEX package. (lib/)
	Added TREE-COPY procedure. (lib/)
2010-07-06
	Added auto-completion to ARSE. (contrib/)
	Added ADJOIN, SET-DIFFERENCE, and SUBSET? procedures. (contrib/)
	Added <TYPE>-COPY procedure to DEFINE-STRUCTURE. (lib/)
	Replaced lots of REVERSEs with REVERSE!. (*)
2010-07-05
	Added POSITION and friends to library. (lib/)
	ARSE: fixed tab expansion; added "unexpand" option. (contrib/)
2010-07-04
	Added the AMB (backtracking) operator. (lib/)
	Added HASH-TABLE-REMOVE! and ALIST->HASH-TABLE; renamed
	HASH-TABLE->LIST to HASH-TABLE->ALIST. (lib/)
	Fix: (cond ('(()))) was an error. (s9.c)
2010-07-03
	Fix: FOR-ALL sometimes returned #T unexpectedly. (lib/)
	Fix: CALL/CC could crash AND, BEGIN, COND, and OR. :-/ (s9.c)
	Added ARRAY-MAP procedure. (lib/)
2010-07-02
	Added more array operations. (lib/)
2010-07-01
	Added Common LISP-style CATCH/THROW. (lib/)
	Added ARRAYs and array operations. (lib/)
2010-06-30
	Renamed DEFINE-RECORD to DEFINE-STRUCTURE, allowed simpler
	slot syntax. (lib/)
2010-06-29
	ARSE: reload main buffer automatically when recovering from
	a REPL error. (s9.c)
	ARSE: fix: undo delete lines at end of buffer. (contrib/)
2010-06-28
	Renamed EXPAND-MACRO to MACRO-EXPAND (more CL'ish). (s9.c)
	Added MACRO-EXPAND-1 procedure. (s9.c)
	Added Common LISP TAGBODY to library. (lib/)
2010-06-27
	Added CALL-WITH-CURRENT-CONTINUATION (CALL/CC). (s9.c)
	Related critical change in s9.c:_eval():
		  name = car(rib_source(rib));
		- /* Save result */
		- car(Stack) = Acc;
		  if (Trace_list != NIL)
	Imported CALL/CC description from R4RS. (help/)
	Added LET/CC to library. (lib/)
	Added cooperative thread functions. (lib/)
	Removed CALL-WITH-ESCAPE-CONTINUATION.
2010-06-26
	Added REVERSE! primitive and used in some places. (s9.c, s9.scm)
	Made (re-match (re-comp "^") "foo") ==> ((0 0))
	 and (re-match (re-comp "$") "foo") ==> ((3 3)). (lib/)
	Added 'ALL option to RE-MATCH. (lib/)
	Added VECTOR-MAP, made VECTOR-MAP! variadic. (lib/)
	Added STRING-MAP and STRING-MAP!. (lib/)
2010-06-25
	Made S9 ignore SIGPIPE, so the SYS: procedures can catch broken pipe
	conditions themselves. (ext/)
	ARSE: ignore broken pipe condition when writing to REPL. (contrib/)
	ARSE: added autocenter option. (contrib/)
	Cleaned up the REGEX procedures and added submatches. (lib/)
	Made RE-MATCH return ranges rather than strings. (lib/)
2010-06-24
	Misc. clean-up.
2010-06-23
	Factored out all the S9fES stuff in ARSE, so it can be ported to
	other Schemes more easily. (contrib/)
	ARSE: [r] did not check autoindent option. (contrib/)
	Added ARSE porting instructions. (contrib/)
	Added VECTOR-MAP! and STRING-SCAN procedures. (lib/)
	ARSE: expanding tabs to spaces when reading filters, etc. (contrib/)
2010-06-22
	Added DEFINE-RECORD syntax. (lib/)
	(DEFINE-SYNTAX (F ...) <BODY>) accepted only a single-expression
	body. Fixed that. (s9.c)
	ARSE: no longer displaying the REPL buffer when reloading or
	recompiling. (contrib/)
	ARSE: some general clean-up. (contrib/)
2010-06-21
	Finished Unix extension test suite. (util/)
	Documented SYS:SLEEP, SYS:USLEEP. (help/)
2010-06-20
	SYS:CHOWN did not work. (ext/)
	ARSE: :s/<old>/... did not allow leading blanks in <old>. (contrib/)
	ARSE: missing REAL-POS! in SUBSTITUTE and COLON-READ. (contrib/)
	Added SYS:SLEEP, SYS:USLEEP procedures. (ext/)
2010-06-19
	Removed SYS:LCHMOD; not portable. (ext/)
	Cleaned up symlinks in help directory. (help/)
2010-06-18
	Fix: hash tables did not allow negative numeric keys. (lib/)
2010-06-17
	Added a quick and dirty dependency checking mode to S9RESOLVE.
	(prog/)
	Fixed some unresolved library dependencies. ;-)
	* Explanation:
	* The default image file contains most of the S9fES library
	* functions, so it does not really need all those LOAD-FROM-LIBRARY
	* calls. However, I consider it to be good style to make library
	* dependencies explicit by adding them anyway. S9RESOLVE -d detects
	* missing LOAD-FROM-LIBRARYs.
2010-06-16
	Factored out FIND-HELP-PATH procedure. (ext/)
	Added SPAWN-SHELL-COMMAND procedure. (ext/)
	SPAWN-COMMAND has new semantics, SPAWN-SHELL-COMMAND implements
	the old behavior. (ext/)
	Added more missing symlinks to help directory. (help/)
2010-06-14
	Added the SYS:FILENO procedure. (ext/)
	Fix: SYS:SELECT sometimes returned #F even when some
	descriptors were ready. (ext/)
	Fix: PP-FILE could not find LINEFEED procedure. (contrib/)
	Made the pretty-printer indent embedded IF, COND, etc in
	code mode rather than data mode. (contrib/)
2010-06-13
	Removed CURS:KEY-EOL from curses, because it is not the key
	labeled "END" on a PC keyboard. Which KEY_ constant is used
	for this key? My /usr/include/curses.h says KEY_SELECT, but
	this does not appear to make sense. (ext/)
2010-06-12
	Made READ-FROM-STRING skip over comments in multi-line input.
	(contrib/)
	Added SYS:CATCH-ERRORS and SYS:STRERROR primitives. (ext/)
	Made SPAWN-COMMAND redirect stderr of the spawned command to
	stdout so it can be read by the parent. (ext/)
	Added URL-DECODE procedure to library. (lib/)
2010-06-11
	Added the PP-STRING procedure to the pretty-printer. (contrib/)
2010-06-10
	Added the INET-SERVER procedure to the extension library. (ext/)
	Rewrote S9HTS using INET-SERVER. (prog/)
	Reinstalled and fixed a load of wrong or missing symlinks in
	help directory. (help/)
2010-06-09
	Added the SPLIT-URL procedure to the library. (lib/)
2010-06-08
	Added SYS:INET-GETPEERNAME primitive to Unix extension. (ext/)
	Implemented S9HTS, a simple HTTP server. (prog/)
	Added STRING-POSITION and friends to library. (lib/)
	Added STRING-LAST-POSITION and friends to library. (lib/)
2010-06-06
	Added the CURSES_RESET compile time option, which will
	run CURS:ENDWIN automatically in the REPL, so Curses
	cannot hose the interface in interactive sessions.
	Of course, when using this option, (CURS:INITSCR) will
	not have any effect when entered at the REPL. (s9.c)
	Moved ARSE (was: SCHED) to contrib/, kept only the
	command line interface in prog/.
	Added ARSE installation procedure to Makefile.
	Documented ! option. (s9.1)
	Fix: not all globals were initialized in PRETTY-PRINT. (contrib/)
	Fix: PP printed a lonely closing paren in intended applications
	with no arguments. (contrib/)
2010-06-05
	Added !image option to change the heap image name ad hoc. (s9.c)
2010-06-02
	Fixed a few bugs in ADVGEN; it only worked due to the below
	bug in S9. :-/
2010-06-01
	Fix: Local environments of *dynamically* scoped (a.k.a. top-level)
	procedures were still being propagated to functions called *iff*
	there were multiple levels of local definitions in the top-level
	procedure, e.g.:
	(define (g) x)
	(define (f) (let ((x 0))
    	              (let () ; <-- this triggered the bug
      	                (g)
      	                #f)))
	(f) ==> 0 ; should be an error (x undefined)
	This is definitely fixed now. Regression test added. (s9.c)
2010-05-31
	Intercepted more funny characters. (s9.c)
2010-05-30
	Made STRING->NUMBER accept base prefixes. (s9.scm)
	Replaced some applications of the obsolete WRONG procedure
	with applications of ERROR. (s9.scm)
	Made the interpreter identify funny input characters. (s9.c)
2010-05-28
	Fixed a GC bug introduced by growing the pools independently.
	This bug was triggered by using more vector space than node
	space. (s9.c)
	Improved the stress test suite. (util/)
2010-05-27
	ADVGEN: renamed GO/RET to GO/SEL. (prog/)
	Tweaked the sample adventure. (prog/)
2010-05-26
	S9 now takes its image name from argv[0] instead of
	hardwiring it. (s9.[ch])
	Added new FORMAT help page with better explanations and
	lots of examples; try (help 'format). (help/)
2010-05-25
	Fix: FORMAT recursed indefinitely in case of an error
	due to re-use of the name ERROR. (contrib/)
2010-05-24
	Added expansion template to AND-LET* description. (lib/)
	Added Curses interface help pages. (help/)
	Added CURS:LINES and CURS:COLS procedures. (ext/)
	Fix: MAKE-STRING did not type-check second argument. (s9.c)
2010-05-23
	Added first version of a CURSES(3) interface. (ext/)
	Fixed GC bug in APPEND2.
	Made cons and vector pools grow independently. (s9.c)
2010-05-22
	Stopped interpreter from reporting infinite sequences of '('
	in error messages, even if the reported structure is cyclic.
	Added AND-LET*. (lib/)
	Minor cosmetics.
2010-05-21
	Improved limited output in error messages. (s9.c)
	Running "make tests" will now use a minimum heap image,
	so unresolved references in the library will be detected.
	(Makefile)
	Improved ADVGEN error messages. (prog/)
	Added COPY-FROM special description to ADVGEN. (prog/)
2010-05-20
	Made DEFINE-SYNTAX an alias for DEFINE-MACRO; removed
	DEFINE-MACRO. (s9.c)
	Moved SYNTAX-RULES to the extension library. (lib/)
	Added the STANDARD-ERROR-PORT, WITH-OUTPUT-TO-STDERR,
	and CALL-WITH-STDERR procedures. (ext/)
	Limited size of Scheme objects in error messages. (s9.c)
	Updated S9(1) man page and help pages. (help/)
	Various small fixes and cosmetics.
2010-05-19
	Added GO/RET operator to ADVGEN. (prog/)
	Applied various minor improvements to the pretty-printer.
	(contrib/)
	Added default values to PARSE-OPTIONS!. (ext/)
	Added SCMPP pretty-print utility. (prog/)
	Added more features to ADVGEN; see prog/advgen.txt.
2010-05-18
	Fixed a long-standing bug that caused the following program
	to evaluate to 1:
	(define (g) x)
	(define (f)
	  (let ((x 1))
	    (g)
	    #f))
	(f)
	This happened only if (g) was *not* a tail call. The critical
	part of the fix is:
	+       if (!tail && cdr(Environment) != NIL)
	+               Environment = cdr(Environment);
	in s9.c:bind_arguments().
2010-05-17
	Added ADVGEN documentation, fixed some minor bugs. (prog/)
2010-05-16
	Added GO/CUT operator to ADVGEN. (prog/)
	Added STRING-FIND-LAST, STRING-FIND-LAST-WORD,
	STRING-CI-FIND-LAST, STRING-CI-FIND-LAST-WORD. (lib/)
	Fix: SCM2HTML did no longer accept input from stdin. (prog/)
	Fix: SCM2HTML rendered #[bdox] literals in wrong color. (prog/)
	Fix: ADVGEN: stupid bug in HTML postlude. (prog/)
	Fix: SCM2HTML: #\$ is a valid symbol character. (prog/)
	Added missing symlinks to help database. (help/)
2010-05-15
	Documented NAME->FILE-NAME. (contrib/)
	Added code to install utility programs. (Makefile)
	Added COUNTER option type and "--" special argument
	to PARSE-OPTIONS!. (ext/)
	Added ADD/GO and REM/GO actions to ADVGEN. (prog/)
2010-05-14
	Added new option types to PARSE-OPTIONS!. (ext/)
2010-05-13
	Added STRING-TRANSLATE procedure to library. (lib/)
	Finished sample ADVGEN adventure. (prog/)
	Fixed a bug in PARSE-OPTIONS!: option args were always
	taken from first option. Oops. (lib/)
2010-05-12
	Fixed names in error messages of CAAR..CDDDDR. (s9.c)
	Implemented first version of ADVGEN, an HTML adventure
	generator. (prog/)
2010-05-11
	Made email addresses in the code harder to harvest.
2010-05-10
	Added HTMLIFY utility. (prog/)
	Added stuff for automatic web site creation. (util/)
2010-05-09
	Renamed all UNIX:... symbols to SYS:... and made naming
	more consistent. All names in the SYS-UNIX extension now
	begin with SYS:. (ext/)
	Moved SYS:FLUSH with no args to library (FLUSH-OUTPUT-PORT). (ext/)
	Added LETREC* syntax. (lib/)
2010-05-08
	While I am at it: made these procedures primitives:
	APPEND, LIST-TAIL, MIN, MAX. (s9.c, s9.scm)
	Fixed READ-FROM-STRING (mixed up some numbers and
	symbols). (lib/)
	Added #B, #D, #O, #X prefixes to READ-FROM-STRING. (lib/)
	Renamed STRING-FIND to STRING-LOCATE and STRING-CONTAINS
	to STRING-FIND. Also swapped the arguments of STRING-FIND
	so that STRING-FIND and STRING-LOCATE are more consistent
	now. (lib/, contrib/)
	Added [+-][st] modifiers to CHANGE-MODE. (ext/unix.scm)
2010-05-07
	Made these procedures primitives: ABS, ASSQ, ASSV,
	CAAR..CDDDDR, EQV?, EVEN?, LENGTH, LIST, MEMQ, MEMV,
	NEGATIVE?, NOT, NULL?, ODD?, POSITIVE?, REVERSE, ZERO?.
	Resulting speed increase is between 30% (libtest) and
	70% (htmlize library). (s9.c, s9.scm)
	Added -9 (highlight non-R4RS symbols) and -x (highlight
	extensions) arguments to SCM2HTML utility. (prog/)
	Added indentation of DO. (contrib/pretty-print.scm)
	Fixed evluation of DO in PROGRAM?: allowed more than
	one statement in body, made statement in termination
	clause optional. (lib/programp.scm)
2010-05-06
	Made DRAW-TREE print more compact trees by emitting the
	conses of (...(x)...) as soon as possible. (contrib/draw-tree.scm)
	Added interactive mode to SOCCAT program. (prog/)
	Added UNIX:ACCESS help page.
2010-05-05
	Added purely functional streams to library. (lib/streams.scm)
	Added UNIX:WAITPID procedure.
	Fixed type checking in UNIX:KILL (accepted single argument).
	Added the SOCCAT utility. (prog/soccat)
2010-05-04
	Added UNIX:SELECT procedure.
2010-05-03
	Made argument of FLUSH optional (defaults to current output port).
	Added UNIX:INET-CONNECT, UNIX:INET-LISTEN, and UNIX:INET-ACCEPT
	procedures.
	Made UNIX:* procedures print more informative error messages.
	Added mode argument to UNIX:MKDIR, made it optional in MKDIR.
2010-05-02
	Made UNIX:STAT not follow symlinks.
	Added STRING-CONTAINS-WORD and STRING-CI-CONTAINS-WORD. (lib/)
	Added FIND-HELP procedure. (ext/)
	Made PARSE-OPTIONS! accept symbolic options (instead of strings).
2010-05-01
	Added UNIX:SETUID, UNIX:SETGID. UNIX:GETPGID, UNIX:SETPGID.
	Added DISPLAY*. (lib/)
2010-04-30
	Added the UNIX:FORK, UNIX:WAIT, and UNIX:EXECV procedures.
	Added the UNIX:ACCESS and SEARCH-PATH procedures. (ext/)
	Replaced the primitive UNIX:SPAWN and SPAWN procedures with
	the high-level SPAWN-COMMAND procedure. (ext/spawn-command.scm)
	Added S9RESOLVE program, which resolves S9fES library
	dependencies. (prog/)
	Hash tables sizes now adapt automatically. (lib/hash-table.scm)
2010-04-29
	Added more Unix procedures: UNIX:CLOSE, UNIX:CREAT, UNIX:DUP,
	UNIX:DUP2, UNIX:LSEEK, UNIX:MAKE-INPUT-PORT, UNIX:MAKE-OUTPUT-PORT,
	UNIX:OPEN, UNIX:PIPE, UNIX:READ, UNIX:WRITE, UNIX:UMASK.
	Also added the APPEND-TO-OUTPUT-FILE procedure. (ext/)
2010-04-28
	Added PARSE-OPTIONS! and friends. (ext/parse-options.scm)
	Installing contribs directly in @S9DIR@ now.
	Made UNIX:READDIR skip the "." and ".." entries.
	Added UNIX:RENAME procedure.
2010-04-27
	Added the STRING-UNSPLIT procedure (lib/).
	Made HASH-TABLE-REF return just a value (lib/hash-table.scm).
	Error messages are now printed on stderr when the interpreter
	runs in quiet mode (-q).
	Added DIRNAME procedure.
	Moved contrib/pretty-print.scm to prog/scm2html.scm and made
	it a stand-alone program.
	Moved S9 configuration from Makefile to config.scm.
2010-04-26
	Added help pages for all remaining UNIX: procedures.
	Added the STAT-type? predicates for finding out the
	type of a directory entry.
	Added the BASENAME procedure.
	Removed the S9U(1) man page, because it basically duplicates
	the help pages.
	Added "programs" section (prog/) and dupes program.
2010-04-25
	Added "pattern=mode" to UNIX:CHMOD.
	Added some UNIX: procecures to the help database.
	Added STRING-PARSE procedure.
	Made STRING-SPLIT generate empty strings when multiple
	subsequent separators are found.
	Updated S9U(1) man page (was S9E(1) man page).
	Updated help pages.
2010-04-24
	Merged S9 and S9E interpreters; configure in Makefile.
	Added third return value (PID) to UNIX:SPAWN.
	Added UNIX:KILL and KILL procedures.
	Added R4RS test cases to test suite.
2010-04-23
	Removed real number stuff.
	Removed Scientific Calculator stuff.
	Removed statistics package.

-------------------------------------------------------------------------------
	Forked this version.
-------------------------------------------------------------------------------

2009-09-06
	Removed EXPAND-QUASIQUOTE. It is no longer needed, because
	EXPAND-MACRO can now be used to expand quasiquoted forms.
	Documented the interpreter start-up process in the man page.
	Renamed WRONG to ERROR to make it more compatible with
	SRFI-23 error reporting.
2009-09-05
	Rewrote QUASIQUOTE as a macro and removed all quasiquotation
	functionality from the C part.
2009-09-03
	Included "./lib" and "./contrib" in DEFAULT_LIBRARY_PATH, so
	S9 can load libraries after just compiling it in its build
	directory.
	Added the S9:S9 start-up hook. When a nullary procedure named
	S9:S9 exists, it will be called when S9 starts.
	Added the DUMP-IMAGE primitive, which allows to write a new
	heap image from the REPL.
	Updated the help pages.
2009-09-02
	Made SQRT return an exact value whenever possible.
2009-08-14
	Fix: '() printed two ()'s (was introduced with #<NaN>).
	Added the UNSORT procedure to LIB.
2009-08-11
	Fixes:
	- Cleaned up the SC extension;
	- Added missing S9SC(1) man page.
	Thanks again, Masaru KIMURA.
2009-08-08
	Added constants for options, so you can write
	(plot* -7 7 sin type: scatter style: 3)
	instead of
	(plot* -7 7 sin 'type: 'scatter 'style: 3).
2009-08-07
	Added 'X-GRID: and 'Y-GRID: options to S9SC SETUP procedure.
	Added abbreviations, e.g.: 'STEP: for 'X-STEP: and 'Y-STEP:, etc.
	Fix: second argument of EXPT could not be real.
2009-08-06
	Added option argument checking to S9SC procedures.
	Fix: made PRINT-CODE generate proper links for LOAD-FROM-LIBRARY
	arguments without ".scm" suffix.
2009-08-05
	Wrote the S9SC(1) man page.
2009-08-04
 	Re-organized the extension libraries.
	Renamed the GFX extension to SC.
	Added initialization procedures to extensions.
	Made (LOG N) return #<NaN> for non-positive N.
2009-07-26
	Fixed some warnings in GFX extension. Thanks, Barak Pearlmutter.
2009-07-25
	Added statistics package to CONTRIB.
	Added the Scheme 9 Scientific Calculator extension (S9SC).
	Note that S9SC is *very* experimental at this stage.
2009-07-08
	Fixed that rounding bug in ATAN.
2009-07-05
	Test suite failed on 64-bit machines due strange rounding
	errors in ATAN. Decreased accuracy to 4 digits as a lame
	work-around. Suggestions welcome.
2009-07-04
	Added support for unspecific digits (#) to STRING->NUMBER.
	Fix: (ASIN 1) and (ACOS 0) were undefined.
	Fixed some minor flaws.
	Added tests for ACOS, ASIN, ATAN, and STRING->NUMBER.
2009-07-01
	Added the ACOS, ASIN, ATAN procedures.
	Fix: real number normalization *first* removed trailing
	zeros and *then* truncated the mantissa. Oops.
2009-06-29
	Added '#' syntax for unspecific digits in inexact numbers.
2009-06-26
	Fix: STRING->NUMBER always returned an inexact result for
	real number representations.
2009-06-25
	Fix: Stack was not cleaned up properly in some error conditions.
	Fix: (*) and (+) could crash the interpreter.
	Internal: Added 64-bit emulation for 32-bit systems.
2009-06-15
	Minor cleanup, added comments where necessary.
	* Do not expect any updates in the near future.
	* I need a break from programming.
	* Bug reports are still welcome, but will get low
	* priority for now.
2009-06-09
	Fixed a variable collision in the hash table implementation.
	(lib/hash-table.scm)
2009-06-08
	Made PRINT-CODE recognize new numeric functions as primitives.
	Fixed INVERSEO procedure in AMK.
2009-06-07
	Made STRING->NUMBER recognize real numbers.
	Fix: missing initialization of got_d in string_numeric().
	Fix: FLOOR and EXACT->INEXACT did not normalize their results.
	Simplified counter_to_string(), based on code by Masaru KIMURA.
	Added loads of tests for STRING->NUMBER.
2009-06-06
	Extended domain of NUMBER->STRING to REAL.
	Added support for the "precision markers" D,F,L,S, although
	only one floating point precision exists.
	Fix: MANTISSA did not return negative signs.
	Fix: INEXACT->EXACT lost the sign of its operand.
	Fix: #I created a double sign in negative integers.
	Added/updated help pages for various procedures.
	Added more tests.
2009-06-05
	Fix: SIN, COS, TAN expected degrees, should be radians. Oops.
	Ran further 64-bit tests on the Alpha, all passed.
2009-06-04
	Implemented LOG and EXP procedures. Added tests.
	Fixed size of Called_procedures[]. Good catch, Masaru KIMURA.
2009-06-03
	Implemented CEILING, FLOOR, ROUND, TRUNCATE procedures.
	Implemented SIN, COS, and TAN procedures.
	Added tests for all of the above.
	Made procedures expecting integers accept real numbers too, as
	long as they are exact and can be converted to integer without
	loss of precision. Added tests.
	Made the reader accept an excess number of digits in the mantissa,
	giving an inexact number.
2009-06-02
	* I have tested this release on my Alpha with -DBITS_PER_WORD_64
	* and it passed all tests. If make test still fails on Linux/PPC,
	* I would need SSH access to a PPC box to investigate further.
	Implemented SQRT.
	Fixed INTEGER? (mistook random objects for integers).
	Removed some 64-bit glitches.
	Applied some cosmetics.
	Added test cases.
2009-06-01
	Implemented real number division (/).
	Made INTEGER? return #T for reals that can be converted to
	integer without loss of precision.
	Made INEXACT->EXACT return an integer whenever possible.
	Extended domain of EXPT to real.
	Implemented the internal EXPONENT and MANTISSA procedures.
	Fixed a GC leak in real_normalize(). Thanks, Masaru KIMURA.
	Added test cases for / and EXPT.
	Added more type test cases.
	Updated the S9(1) man page.
2009-05-31
	Implemented real number multiplication (*).
	Just try: (expt 9.9 999999999). Is this cool?
	Intercepted numeric underflow and overflow.
	Added test cases for real *.
	Added #E and #I syntax.
	Added real number test cases for #E, #I, EXACT->INEXACT,
	INEXACT->EXACT, NEGATIVE?, POSITIVE?, ZERO?.
2009-05-30
	Fixed INEXACT->EXACT (sign error).
	Implemented real -.
	Implemented exactness in
	- the +, MIN, and MAX procedures;
	- bignum-->real conversion;
	- real number normalization.
	Added real number tests for -, ABS, MIN, MAX.
	Added test cases for EXACT->INEXACT and INEXACT->EXACT.
2009-05-29
	Implementated real +.
	Implemented EXACT? and INEXACT?.
	Implemented EXACT->INEXACT and INEXACT->EXACT.
	Fixed a few bugs in real <.
	Added real number tests for +.
2009-05-28
	Added more test cases for real <.
	Extended domains of <=, >, >= to real.
	Added real number tests for <=, >, and >=.
	* Please stress-test the real number routines
	* and do report errors!
	* Suggestions for additional tests are welcome!
2009-05-27
	Added mantissa size to magic ID of image files.
	Implemented comparison of real numbers in <.
	Added real number tests for <.
2009-05-26
	Moved sign of reals to flags field in order to allow for -0.0.
	Changed flat_copy() so that it can copy special atoms, too.
	Added real number tests for =.
	Cleanup.
2009-05-25
	Added a reader and printer for real numbers.
	Implemented internal representation for real numbers.
	Implemented comparison of real numbers in =.
	Added more syntax tests to test suite (primarily in order to test
	the real number reader and printer).
	Added REAL? predicate.
	Made NUMBER? an alias of REAL?.
	Applied some minor cosmetics.
	* Note that you cannot yet do anything really useful with
	* real numbers other than translating them from/to external
	* representation and comparing them.
2009-05-24
	Added code to detect real number syntax and dispatch it to
	a specialized reader. Yes, this is a first step toward real
	number arithmetics, but don't hold your breath right now.
2009-05-23
	Improved the documentation of the matcher package.
	Removed unused list_of_symbols() function from "s9.c".
	Thanks, Masaru KIMURA (also for misc. other cosmetics).
2009-05-22
	Moved "define-match.scm" to "matcher.scm".
	Renamed DEFINE-MATCH to DEFINE-MATCHER, added LET-MATCHER syntax
	to matcher package. Extended matchers so that 'SYMBOL matches a
	literal symbol. (lib/matcher.scm)
	Improved rendering of (cond (p => x)) in pretty printer.
	(contrib/pretty-print.scm)
	Applied various cosmetics.
2009-05-21
	Added STRING-UPCASE and STRING-DOWNCASE procedures.
	(lib/string-case.scm)
2009-05-20
	Simplified HASH-TABLE procedures. (lib/hash-table.scm)
2009-05-17
	Included help pages for ALL procedures of the extension
	library! Just try (load-from-library "draw-tree") and
	then (help 'draw-tree).
	LOAD-FROM-LIBRARY now attaches a ".scm" suffix, if the
	given file cannot be located, i.e., you can write
	(load-from-library "foo") instead of (... "foo.scm").
	Tweaked the image dump/load routines.
	Fixed a (self-made) bug in FORMAT (~A would slashify output).
2009-05-16
	Fix: made strings returned by SYMBOL->STRING immutable.
	Updated the help pages.
	Prepared comments in library files for automatic generation
	of help pages. (Stay tuned.)
2009-05-14
	Added code to grow the memory pools when loading large images.
	Added interpreter tag to magic header (images are not portable).
	Added another tweak for POSIX compatibility.
2009-05-13
	Administrative:
	- Removed all those special variables ($@, $<, ...)
	  from Makefile, because some(?) of them are simply
	  not portable.
	- Added -Dunix to compilation of unix.c (sic!).
2009-05-12
	Applied some cosmetics to s9.scm.
	Administrative: fixed local environment in the build process.
2009-05-11
	Fix: PRINT-CODE handled QUOTE inside of QUASIQUOTE incorrectly.
	(contrib/print-code.scm)
	Fixed a bug that resulted in multiple evaluation of DELAYed
	expressions.
2009-05-10
	Minor fix: protected car(x) in syntax_object_p().
	Cosmetics.
	Changed allocation strategy. We will now use half of the
	memory pool at most. OK, this gives us the same space
	efficiency as a copying collector, but with the advantage
	of having cons objects in fixed places on the heap. The
	performance gain is about 35% (zebra puzzle).
2009-05-09
	Minor fix: protected argument in pp_load().
	Made conceptual difference between string and symbol names
	[string() vs. symbol_name(), string_len() vs. symbol_len()].
	Removed clone_string() due to above separation.
	Using O(1) string_len() instead of O(n) strlen() in pp_gensym().
	Checking length first in STRING=? and STRING-CI=?.
2009-05-07
	Fix: PRINT-CODE generated tag soup when two subsequent
	tokens were to be printed in boldface.
	Added another tweak for Unix portability to s9.h.
2009-05-06
	Administrative change:
	- #ifdef __unix and #ifdef unix are obviously insufficient
	  to check for a Unix system; added -Dunix to Makefile.
	Thanks, Barak Pearlmutter!
2009-05-05
	Administrative changes:
	- Applied some fixes to the build process.
	- Created browsable version of the library code.
	- Added version tag (timestamp) to distribution file.
	- Added deinstall target to Makefile.
2009-05-04
	Replaced '| by ': in ML-style syntax of DEFINE-MATCH,
	because '| is not portable.
	Removed MAP-CAR from documentation, because it is only
	used internally.
	Simplified definition of LETREC (cosmetics).
	Made the code printer generate links to files included
	via LOAD-FROM-LIBRARY. (contrib/print-code.scm)
2009-05-03
	Added a pattern matcher with optional support for ML syntax
	to the library. (lib/define-match.scm)
	Updated the test suite.
	Moved the online help system to contrib. (contrib/help.scm)
	Moved DRAW-TREE to contrib. (contrib/draw-tree.scm)
	Included the pretty-printer and the online help system in
	the default heap image.
2009-05-01
	Fixed some 64-bit flaws.
	Many thanks to Torsten Leibold for giving his
	AlphaStation 200 4/233 to me!
2009-04-29
	Fix: alpha-conversion of recursive SYNTAX-RULES was broken,
	leading to potentially non-hygienic expansion.
	Added SYNTAX-RULES version of FLUID-LET. (lib/fluid-let-sr.scm)
	Fix: line numbers were off after LOAD.
	Moved interactive programs to CONTRIB, even if they have been
	contributed by myself. (pretty-print.scm, print-code.scm)
2009-04-28
	Finished the new and vastly improved pretty-printer.
	(lib/pretty-print.scm)
2009-04-27
	Fixed some bugs in PROGRAM? (DO with multi-expr test part was
	not allowed; commands were not optional).
	Started rewriting the pretty-printer.
2009-04-26
	Reporting file name in messages when using "-f program" option.
	Made the pretty-printer print '`, and ,@ instead of QUOTE,
	QUASIQUOTE, UNQUOTE, and UNQUOTE-SPLICING.
	Still more clean-up.
2009-04-25
	Even more code clean-up.
2009-04-23
	Applied more cosmetics.
2009-04-22
	Improved hashing of lists. (lib/hash-table.scm)
	Added memoization to PROLOG interpreter. (contrib/prolog.scm)
2009-04-21
	Applied various micro optimizations and cosmetics.
	Added == (unify) and DIF goals to PROLOG example.
2009-04-20
	Made the interpreter print file and line number information
	in error messages when LOADing a file.
	Reverted to previous version of the PROLOG interpreter due
	to unclear semantics.
2009-04-19
	Extended the PROLOG interpreter. (contrib/prolog.scm)
2009-04-18
	Added PROLOG interpreter to contrib section. (contrib/prolog*)
2009-04-15
	Fixed some error messages; made messages more uniform.
	Fixed a bug in the reader: the (malformed) expression ('))
	gave a strange result. It is an error now.
2009-04-12
	Documented the VOID procedure.
2009-04-10
	Added numeric base prefixes #B, #D, #O, and #X.
2009-04-09
	Fix: STRING-FILL! and VECTOR-FILL! should not be able to mutate
	string and vector literals, either.
2009-04-08
	Added the STATS primitive, which evaluates an expression and
	then prints some interesting data gathered during evaluation.
	Added the VOID procedure, which evaluates to an unspecific value.
2009-04-03
       Fix: a #F literal following an ellipsis in DEFINE-SYNTAX/SYNTAX-RULES
       would be substituted by mistake.
2009-03-30
       A Debian package was created by Barak Pearlmutter. Thanks for the
       package and a few minor but useful patches!
2009-03-22
       Made pair, string, and vector literals immutable, so expressions
       like these no longer work:
         (set-car! '(a b) 'c)
         (set-cdr! '(a b) 'c)
         (string-set! "foo" 0 #\g)
         (vector-set! '#(a b) 0 'c)
2009-03-15
       Added code to make S9fES compile with PCC. Wow, PCC is so much
       faster, still generates good code, and comes with a liberal
       license. Bye, bye, GCC.
2009-03-14
       Added FreeBSD port.
       Updated s9(1) man page.
2009-03-13
       Fix: made quasiquotation of improper lists work.
       Fix: rewrote the high-level syntax matcher and expander.
       DEFINE-SYNTAX and SYNTAX-RULES should work as expected now,
       including multiple ellipses, etc.
       Made the interpreter report nested QUASIQUOTE (which is
       currently unsupported).
       Added UNIX:UNLINK primitive to extended interpreter.
       (ext/unix.c)
2009-03-12
       Made unix extension procedures return #F in case of an error
       instead of just aborting evaluation.
       Added UNIX:ERRNO primitive to extended interpreter. (ext/unix.c)
       Updated README, fixed s9e(1) man page, updated the binary for
       the unmentionable horror.
2009-03-11
       Added UNIX:READDIR and UNUX:READLINK primitives to extended
       interpreter. (ext/unix.c)
       Added UNIX:GETPWENT primitive to extended interpreter.
       (ext/unix.c)
2009-03-10
       Added FORMAT-TIME procedure to the system extension.
       (ext/system.scm)
       Updated s9e(1) man page.
2009-03-09
       Added UNIX-TIME->TIME and TIME->UNIX-TIME procedures to the
       system extension. (ext/system.scm)
2009-03-08
       Fix: removed recursion from GC of vectors. The garbage collector
       runs completely in constant space now. Yay!
2009-03-03
       Made CHOWN accept user names and default values.
       (ext/system.scm)
2009-03-02
       Added UNIX:GETGRNAM and UNIX:GETGRGID primitives to Unix
       extensions. (ext/unix.c)
       Added bitwise logic operations to library: BITWISE-CLEAR,
       BITWISE-AND, BITWISE-AND-C2, BITWISE-1, BITWISE-AND-C1,
       BITWISE-2, BITWISE-XOR, BITWISE-OR, BITWISE-OR-NOT,
       BITWISE-XOR-NOT, BITWISE-C2, BITWISE-OR-C2, BITWISE-C1,
       BITWISE-OR-C1, BITWISE-AND-NOT, BITWISE-SET, BITWISE-SHIFT-LEFT,
       BITWISE-SHIFT-RIGHT. (lib/bitwise-ops.scm)
       Made CHMOD accept symbolic and octal modes. (ext/system.scm)
       Made argument of EXIT optional. (ext/system.scm)
2009-03-01
       Made the interpreter abort earlier in case of an error.
       Added hash table procedures to library. (lib/hash-table.scm)
2009-02-28
       Added support for radixes from 2 to 36 to NUMBER->STRING and
       STRING->NUMBER. Not R4RS, but nice and trivial to implement.
       Added READ-FILE procedure to library. (lib/read-file.scm)
       Added STRING-FIND (fast string search) procedure to contrib.
       (contrib/string-find.scm)
2009-02-27
       The code printer now supports vectors. (lib/print-code.scm)
       New: added contrib directory containing code by other authors.
       Added Common Lisp-style FORMAT to contrib section. Thanks, Dirk
       Lutzebäck. (contrib/format.*)
2009-02-26
       Fix: the interpreter now accepts newline characters in string
       literals.
       Fixed quotation of strings in the WRITE-TO-STRING library
       procedures.
       Added DISPLAY-TO-STRING (lib/write-to-string.scm).
2009-02-25
       Fix: test part of DO should accept multiple expressions.
       Added TRACE primitive. See man page for details.
       Fixed a bug in the PROGRAM? library function (LAMBDA should
       accept multiple expressions).
2009-02-22
       Updated the help pages (included descriptions of dynamic
       top-level variables).
       Added the FLUID-LET syntax to the library (lib/fluid-let.scm).
2009-02-09
       Updated man page and help entry for DEFINE-MACRO.
2009-02-04
       Added support for named LET to the pretty-printer
       (lib/pretty-print.scm).
2009-02-03
       Added the PROGRAM? predicate to the library (lib/programp.scm).
       Added automatic code/data detection to the pretty-printer
       (lib/pretty-print.scm).
2009-02-02
       Added formatting of DO to the pretty-printer
       (lib/pretty-print.scm).
2009-02-01
       Cleaned up installation process.
       Fixed vector output and quotation in the pretty-printer
       (lib/pretty-print.scm).
2009-01-30
       Fixed indentation of lambda function applications in the
       pretty-printer (lib/pretty-print.scm).
2009-01-29
       Allowed multiple occurrences of the -f program switch on the
       command line.
       Fixed packaging error: library files (lib/) were missing.
2009-01-28
       Updated documentation.
2009-01-27
       Applied some cosmetical changes (mostly s9.scm).
       Added some test cases for multiple expressions in bodies.
2009-01-26
       Improved syntax checking of LET*.
       Fix: the else clause of CASE evaluated only the first expression
       of its body.
       Fix: DO now binds variables in each iteration rather than
       mutating them.
2009-01-25
       Added the APROPOS procedure to the help system
       [(load-from-library "help.scm")].
       Added a help page for DEFINE-MACRO.
2009-01-24
       New: Finished the online help system that is based on the R4RS
       document. Try (load-from-library "help.scm") and then (help).
       Use (set! *lines-per-page* ...) to adjust the system to your
       preferred screen size.
       Improved DEFINE-SYNTAX and SYNTAX-RULES (added support for
       multiple ellipses per pattern). DEFINE-SYNTAX is still quirky,
       though.
2009-01-21
       Added the -i (ignore rc file) command line option.
2009-01-20
       Fix: SYMBOLS was broken by macro expansion.
2009-01-19
       Added STRING-CONTAINS to the library.
       Factored out the LOCATE-FILE procedure, which locates a file in
       $S9FES_LIBRARY_PATH (s9.scm).
       Fixed the implementation of DELAY (it now passes all tests of
       Aubrey Jaffer's R4RS test suite).
2009-01-18
       Added pretty-printer to the library (lib/pretty-print.scm).
       Added code printer to the library (lib/print-code.scm). The
       PRINT-CODE procedure renders Scheme code in HTML with syntax
       highlighting and optional CSS2-based paren matching.
2009-01-17
       Added the DRAW-TREE procedure to the library.
       Fix: bodies of local DEFINEs may have more than one expression
       now.
       Fix: interpreter no longer breaks when attempting to expand
       incomplete quotation and quasiquotation.
2009-01-16
       Updated manual pages.
       Removed FOLD-LEFT and FOLD-RIGHT from the library, because the
       S9fES core already contains them.
       Made FOLD-LEFT, FOLD-RIGHT, and map accept lists of different
       lengths.
2009-01-15
       Added ML-style record data type to library (records.scm).
       Added the SYMBOLS primitive which returns a list of defined
       symbols.
2009-01-14
       Added Another Micro Kanren (amk.scm) and the zebra example
       (zebra.scm) to the library.
       Added automatic library testing (libtest.sh).
2009-01-13
       Imported the regular expression matcher of zenlisp
       (lib/regex.scm).
       Added the STRING-SPLIT, READ-FROM-STRING, AND WRITE-TO-STRING
       procedures to the library.
       Fixed DEFINE-SYNTAX: templates now may contain syntactically
       incorrect binding constructs. Yes, this is important; see
       lib/module.scm for an example.
       Added simple module syntax to the library (module.scm).
2009-01-12
       Removed the SQRT procedure, because it always returned an
       integer. This procedure will be included in a future version as
       INTEGER-SQRT.
       Added the following procedures to the library of loadable
       functions: COMBINE, COUNT, DEPTH, EXISTS, EXPLODE, FACTOR,
       FACTORIAL, FILTER, FLATTEN, FOLD-LEFT, FOLD-RIGHT, FOR-ALL,
       HYPER, IMPLODE, INTEGER-SQRT, INTERSECTION, IOTA, LIST->SET,
       MAKE-PARTITIONS, MERGESORT, PARTITION, PERMUTE, QUICKSORT,
       READ-LINE, REMOVE, REPLACE, SUBSTITUTE, SUM, TRANSPOSE, UNION.
2009-01-11
       Fixed a few more routines that relied on fixed string and vector
       locations and may be broken by vector pool compaction.
       Potentially affected: DEFINE, DEFINE-MACRO, VECTOR->LIST,
       STRING->LIST.
2009-01-10
       I get bitten by this one over and over again. So, note to
       myself:
         C's stupid order of evaluation messes up
         Car[x] = alloc(foo,bar);
         because Car may relocate during GC.
       I have fixed about a dozen instances of this bug in the current
       version, so if you do not like nasty surprises (a.k.a. GC
       leaks), you may want to update.
2009-01-07
       Fix: LOAD-FROM-LIBRARY did not work, because LOAD added bindings
       to the current local environment instead of the global
       environment.
       Loading files should be faster now, because environments are
       re-hashed only once per LOAD.
2009-01-06
       Made s9 -v output more verbose.
       Added LOAD-FROM-LIBRARY procedure.
       Documented internal dynamic variables.
2009-01-02
       Changed allocator strategy. The size of new segments grows
       exponentially now (n^1.5), resulting in a smaller initial memory
       footprint, smaller heap image, and faster adaption to
       memory-intensive applications.
       Changed default memory limit to 12.1M bytes (was 1M bytes).
2009-01-01
       Cleaned up the DEFINE-SYNTAX transformer (s9.scm).
       Fix: the evaluator could block when running out of nodes.
       Added -m size (set memory limit) command line option.
2008-12-14
       Applied some cosmetics.
2008-12-13
       Added -g (GC summaries) command line option.
2008-12-12
       Fixed missing procedure name in some error messages.
2008-12-09
       The interpreter returns to the REPL now when hitting the memory
       limit (MEMORY_LIMIT_KN).
       Changed types of all references to nodes from int to cell in
       order to improve support for 64-bit systems.
       Renamed SYS extension to UNIX.
2008-12-08
       A system called Scheme 9 should run on Plan 9, indeed. Thanks to
       Bakul Shah for pointing this out and helping me to get it
       ported. Thanks to Russ Cox for 9vx.
2008-11-29
       Cleaned up the extension procedure interface. Adding new
       primitives should be a snap now.
2008-11-28
       Cleaned up (internal) definitions of primitive procedures.
2008-11-26
       Moved constant, variable, and macro declarations to a header
       file (s9.h).
2008-11-05
       Fixed a subtle GC bug related to string cloning. Potentially
       affected: STRING-COPY, SYMBOL->STRING, STRING->SYMBOL.
2008-11-01
       Fixed SYS:COMMAND-LINE (would destroy the command line when
       called).
       Cleaned up the build/install process.
2008-10-06
       Fixed a bug that could crash S9 when DEFINEing variables in
       hashed environments. Thanks, Doug Currie.
2008-09-05
       Documented the SYS extension (see s9e(1)).
2008-09-04
       Applied some cosmetics to the syntax rules expander and added an
       example (s9.scm).
2008-09-03
       Applied some cosmetical changes to the C code.
       Cleaned up much of the Scheme code.
       Included experimental SYS extension (see ext/* and EXTENSIONS in s9.c).
       Documented PRINT.
       Added else clause to COND-EXPAND.
       Documented COND-EXPAND.
       Added some macro expansion tests to the test suite.
2007-10-30
       Removed SYNTAX->LIST because it is no longer needed.
2007-10-27
       The interpreter is now printing a call trace in case of an
       error.
2007-10-23
       Fix: DISPLAY can now output NUL characters. (OK, this is not
       really covered by R5RS, but useful, nevertheless.)
2007-10-19
       Extended domain of INTEGER->CHAR to 0..255.
2007-10-17
       Fix: WRITE-CHAR could not output NUL characters.
2007-10-14
       Fix: interpreter core-dumped when $HOME was undefined.
2007-10-07
       Fix: LOAD does not change (CURRENT-INPUT-PORT) any longer.
2007-10-06
       READ now requires string literals to be contained in a single
       line of input.
2007-10-01
       Improved error reporting in DO, LET, and LETREC.
       Allowed multiple expressions in bodies of CASE and improved
       error reporting.
2007-09-28
       Removed record primitives from the interpreter, because they can
       be implemented portably.
2007-09-25
       Removed redundant clauses from FOLD-LEFT and FOLD-RIGHT.
       Fixed a bug in the syntax checker of SYNTAX-RULES.

-------------------------------------------------------------------------------
	Major change: re-implemented DEFINE-SYNTAX/SYNTAX-RULES
-------------------------------------------------------------------------------

2007-09-23
       Applied some cosmetical changes to DEFINE-SYNTAX.
2007-09-21
       Added some syntax analysis and error reporting to DEFINE-SYNTAX.
2007-09-20
       Added optional string argument to GENSYM. This argument is used
       as a prefix in generated symbols.
       Added an experimental implementation of DEFINE-SYNTAX and
       SYNTAX-RULES in terms of DEFINE-MACRO.
       Added header to image file format.
2007-09-14
       Updated the man page.
2007-09-13
       Added RECORD-TYPE-MATCHES?.
2007-09-12
       Added record tests to test.scm.
2007-09-11
       Added (record-copy record) => record.
       Added (record-signature record) => sig.
       Added (assert-record-type sig record) => record.
2007-09-10
       Added first-class records as an experiment, including the
       following items:
       - Record syntax and external representation:
         #r((tag value ...)).
       - EQUAL? now applies RECORD-EQUAL? to pairs of records.
       - New procedures:
            - (record '(tag value) ...) => record
            - (record? expr) => boolean
            - (record->list record) => list
            - (list->record list) => record
            - (record-ref record tag) => form
            - (record-set! record tag value) => unspecific
            - (record-equal? record1 record2) => boolean
2007-09-09
       Fix: SIGINT could not interrupt runaway macro expansion.
2007-09-08
       Added support for extension procedures (ext/*, experimental, not
       yet in the distribution archive).
2007-09-04
       Cleaned up the LET macro.
       Documented macros (S9(1)).
       Extended and cleaned up the test suite.
2007-09-03
       Removed EXPAND-SYNTAX procedure.
       Added EXPAND-MACRO procedure.
       Added DO macro.
       Added heap image support for faster start-up.
       Added => syntax of COND.
       Added named LET syntax.
2007-09-02
       Removed DEFINE-SYNTAX and SYNTAX-RULES. It is too cumbersome for
       some purposes and too complex internally.
       Implemented DEFINE-MACRO.
       Added GENSYM procedure, because it is required to write some
       macros.
       Rewrote LET, LETREC, LET*, CASE, DELAY using DEFINE-MACRO.

-------------------------------------------------------------------------------
	Major change: switching from DEFINE-SYNTAX to DEFINE-MACRO
-------------------------------------------------------------------------------

2007-08-29
       Misc. small, cosmetical changes.
2007-08-20
       Achieved a speed-up of about 10% by the use of hash chaining.
       Fix: heavy computations involving large lists of integers could
       crash the interpreter during GC. Thanks, Mario Deilmann.
2007-08-09
       Made somes changes to support 64-bit architectures (not yet
       finished).
       Fixed two nasty bugs that potentially could crash the
       interpreter.
2007-08-06
       Made OPEN-OUTPUT-PORT fail when the output file already exists.
       This change also affects CALL-WITH-OUTPUT-FILE and
       WITH-OUTPUT-TO-FILE.
       Added DELETE-FILE and FILE-EXISTS? procedures althouth they are
       not R5RS procedures, because they are simply too handy for
       testing file access procedures.
2007-08-05
       Removed segment matches from the syntax expander, because this
       is not required by R5RS, so (x ... y) is not longer a valid
       pattern in SYNTAX-RULES.
       Fix: the body of COND clauses may be empty.
       Fix: made #\SPACE and #\NEWLINE case-insensitive.
       Fix: CALL-WITH-INPUT-FILE and CALL-WITH-OUTPUT-FILE did not
       close their ports before returning.
       Removed #\LINEFEED (not in R5RS).
       Fix: made LIST? detect cyclic structures.
       Removed R6RS-style comments.
       Made the test suite more general, so that it does not make
       assumptions about behavior not specified in R5RS.
2007-07-21
       Fix: Syntax expansion was done after quasiquote expansion, but
       should have done before it.
2007-07-18
       Fixed a bug in _bignum_divide(): a GC leak could occur when the
       divisor was greater than the dividend.
2007-07-16
       Simplified test suite using DEFINE-SYNTAX. It is smaller,
       cleaner, and also siginificantly slower now (due to syntax
       transformation overhead).
2007-07-06
       Applied some minor, mostly cosmetical changes to s9.c.
2007-07-04
       Fix: STRING-APPEND did not check the types of its arguments.
2007-07-03
       Fixed some comments, renamed some variables.
2007-07-01
       Simplified read_c() and turned it into a macro.
2007-06-30
       Changed representation of #<EOF>, #<UNDEFINED> and #<UNSPECIFIC>
       from symbol to integer (optimization).
       Simplified atomp_p() and made it a macro.
       Directed all interpreter output through pr().
2007-06-29
       Fixed a bug in the syntax expander.
2007-05-26
       Adding hash tables broke **. Fixed that.
2007-05-22
       Added hash tables to environments for faster lookup speed.
       Fix: the sane environment was not GC-safe in the REPL.
2007-05-11
       Fix: `'(,(+ 1 2)) reduced to '(,(+ 1 2)). It now (correctly)
       reduces to '(3).
2007-05-05
       Fix: clauses of CASE could not contain multiple expressions.
2007-04-26
       Made missing program file an error condition in -f program
       command line option.
2007-04-24
       Fix: local ports of WITH-INPUT-FROM-FILE and WITH-OUTPUT-TO-FILE
       were not GC-safe.
       Added -q (quiet) command line option.
       Updated man page.
2007-04-21
       Made more cosmetical changes.
2007-04-20
       Made some minor cosmetical changes.
2007-04-19
       Simplified evaluator (saved one unsave/save).
2007-04-18
       Added patches to make s9.c compile on newer MSC compilers.
       Thanks, Blake McBride.
       De-cluttered code by replacing #ifdefs with ifs.
       Added 64-bit mode for bignum integers for faster operation on
       64-bit systems.
       Fixed LET* with multiple expression body.
2007-04-15
       Added error condition for DEFINE in expression context.
       Updated test suite.
2007-04-14
       Implemented local DEFINEs by rewriting them to LAMBDA and SET!
       (like LETREC).
       Added rc file support: if a ~/.s9fes/rc file exists, it is
       loaded at start-up time.
       Updated test suite.
       Updated man page.
2007-04-13
       Implemented QUASIQUOTE, UNQUOTE, and UNQUOTE-SPLICING.
       Added EXPAND-QUASIQUOTE to library. This procedure rewrites
       quasiquoted expressions to expressions not using quasiquotation.
       Note: you currently cannot quasiquote improper lists.
2007-04-12
       Documented ** (most recent top level result).
       Created a distribution archive.
       Added "install" target to Makefile.
2007-04-11
       Added "additions" section to man page. It describes the non-R5RS
       procedures of S9fES.
       Applied some minor optimizations to EXPAND-SYNTAX.
       Moved part of syntax transformation code into s9.c.
       Added DELAY and FORCE to library.
       Added ** symbol, which always binds to the result most recently
       returned to the REPL.
2007-04-10
       Added SIGINT (abort input or interrupt program) and SIGQUIT
       (emergency exit) handlers. If your system does not support POSIX
       signals, compile with -DNO_SIGNALS to omit signal handling.
       Added -ansi -pedantic compilation flags, removed some flaws.
       Implemented DEFINE-SYNTAX and SYNTAX-RULES special form
       handlers.
       Added SYNTAX->LIST helper (non-R5RS; used in syntax expansion).
       Added EXPAND-SYNTAX (non-R5RS), which performs syntax
       transformation behind the scenes.
       Note: This is an import of the potentially buggy SketchyLISP
       syntax transformer. To be improved.
       Added CASE syntax to library.
       Added LET* syntax to library.
       Updated test suite.
2007-04-09
       Added to library: STRING, VECTOR.
       Added to library: NUMBER->STRING, STRING->NUMBER.
       Added to library: CALL-WITH-INPUT-FILE, CALL-WITH-OUTPUT-FILE,
       newline, WITH-INPUT-FROM-FILE, WITH-OUTPUT-TO-FILE.
       Updated test suite.
       Added -f program command line option.
       Added s9(1) man page.
2007-04-08
       Added library s9.scm which is automatically loaded.
       Added list procedures to library: APPEND, ASSOC, ASSQ, ASSV,
       CAAR...CDDDDR, LENGTH, LIST, LIST-REF, LIST-TAIL, LIST?, MEMBER,
       MEMQ, MEMV, NULL?, REVERSE.
       Added equivalence predicates to library: EQUAL?, EQV?.
       Added type predicate to library: NUMBER?, PORT?.
       Added NOT procedure to library.
       Added higher order procedures to library: FOR-EACH, MAP,
       FOLD-LEFT (R6RS), FOLD-RIGHT (R6RS), MAP-CAR (non-R5RS).
       Added arithmetic functions to library: ABS, EVEN?, EXPT, GCD,
       LCM, MAX, MIN, MODULO, NEGATIVE?, ODD?, POSITIVE?, SQRT, ZERO?.
       Updated test suite.
2007-04-07
       Implemented CHAR-DOWNCASE, CHAR-LOWER-CASE?, CHAR-NUMERIC?,
       CHAR-UPCASE, CHAR-UPPER-CASE?, CHAR-WHITESPACE?.
       Implemented STRING-LENGTH, STRING-REF, STRING-SET!.
       Implemented STRING-APPEND, STRING-COPY, STRING-FILL!, SUBSTRING.
       Fixed a bug in string/vector pool compaction.
       Implemented MAKE-STRING, MAKE-VECTOR, VECTOR-FILL!.
       Implemented <=, >, >=.
       Updated test suite.
2007-04-06
       Implemented OPEN-INPUT-FILE, OPEN-OUTPUT-FILE, CLOSE-INPUT-PORT,
       CLOSE-OUTPUT-PORT.
       Made the garbage collector close unused ports.
       Implemented SET-INPUT-PORT!, SET-OUTPUT-PORT!, both non-R5RS.
       These will facilitate the implementation of WITH-INPUT-FROM-FILE
       and WITH-OUTPUT-TO-FILE.
       Fix: made READ-CHAR and PEEK-CHAR return the EOF object on EOF.
       Implemented CHAR-CI<=?, CHAR-CI<?, CHAR-CI=?, CHAR-CI>=?,
       CHAR-CI>?, CHAR<=?, CHAR<?, CHAR=?, CHAR>=?, CHAR>?.
       Implemented STRING-CI<=?, STRING-CI<?, STRING-CI=?,
       STRING-CI>=?, STRING-CI>?, STRING<=?, STRING<?, STRING=?,
       STRING>=?, STRING>?.
       Updated test suite.
2007-04-05
       Implemented I/O ports.
       Implemented CURRENT-INPUT-PORT AND CURRENT-OUTPUT-PORT.
       Implemented INPUT-PORT?, OUTPUT-PORT?, EOF-OBJECT?.
       Fixed sign error in * with odd numbers of arguments.
       Updated test suite.
       Implemented READ, WRITE, DISPLAY.
       Implemented READ-CHAR, WRITE-CHAR, PEEK-CHAR.
2007-04-04
       Chased a GC bug due to C's braindead order of evaluation.
       Growing memory pools work fine now.
       Fixed some potential GC leaks in the bignum code.
       Made QUOTIENT and REMAINDER handle negative signs correctly.
       Brought test suite up to date.
2007-04-03
       Started test suite.
       Fixed a few bugs in cond.
       Implemented SET-CAR!, SET-CDR!, AND VECTOR-SET!.
       Implemented growing memory pools.
2007-04-02
       Moved most of the type checking code to a central procedure.
       Implemented type predicates: BOOLEAN?, CHAR?, INTEGER?, PAIR?,
       PROCEDURE?, STRING?, SYMBOL?, VECTOR?.
       Implemented type conversion procedures: CHAR->INTEGER,
       INTEGER->CHAR, LIST->STRING, LIST->VECTOR, STRING->LIST,
       STRING->SYMBOL, SYMBOL->STRING, VECTOR->LIST.
       Implemented vector procedures: VECTOR-LENGTH, VECTOR-REF.
       Implemented WRONG (non-R5RS).
       Implemented integer (bignum) =.
       Implemented CHAR=? and STRING=?.
2007-04-01
       Implemented COND.
       Implemented LOAD.
2007-03-31
       Implemented integer (bignum) *, QUOTIENT, and REMAINDER.
2007-03-30
       Implemented LETREC.
       Started implementation of bignum arithmetics.
       Implemented integer (bignum) <, +, -.
2007-03-29
       Implemented CONS, CAR, CDR, EQ?.
       Simplified the garbage collector.
       Removed tedious and buggy variable capture code from LAMBDA.
2007-03-28
       Chased a GC leak, found it, splat! --> *
       Implemented primitive procedure framework.
       Implemented APPLY.
2007-03-27
       Implemented DEFINE (dynamically scoped!).
       Fixed a few bugs in variable capture (could not test this
       earlier).
       Implemented LET by rewriting it as an application of LAMBDA.
2007-03-26
       Modified the evaluator to get rid of the L-stack.
       Modified the evaluator to get rid of the B-stack.
       Implemented BEGIN, IF, AND, OR, and SET!.
2007-03-25
       Imported the evaluator from Sketchy LISP.
       S9fES can now run ((lambda (x) (x x)) (lambda (x) (x x))). In
       constant space!
2007-03-24
       Implemented lambda abstraction.
2007-03-23
       Took the garbage collector, reader, and printer from
       Sketchy LISP and gave them an overhaul.
       S9fES supports R6RS-style #|...|# and #;form comments.
