The programmers of old were mysterious and profound. We cannot fathom their thoughts, so all we do is describe their appearance. Aware, like a fox crossing the water. Alert, like a general on the battlefield. Kind, like a hostess greeting her guests. Simple, like uncarved blocks of wood. Opaque, like black pools in darkened caves. Who can tell the secrets of their hearts and minds? The answer exists only in the Tao. -- Geoffrey James, "The Tao of Programming" BROAD OUTLINE SBCL is derived from the 18b version of CMU CL. Most of CMU CL was originally written as part of the CMU Common Lisp project at Carnegie Mellon University. According to the documentation in CMU CL 18b, Organizationally, CMU Common Lisp was a small, mostly autonomous part within the Mach operating system project. The CMU CL project was more of a tool development effort than a research project. The project started out as Spice Lisp, which provided a modern Lisp implementation for use in the CMU community. and CMU CL has been under continuous development since the early 1980's (concurrent with the Common Lisp standardization effort.) Apparently most of the CMU Common Lisp implementors moved on to work on the Gwydion environment for Dylan. CMU CL's CLOS implementation is derived from the PCL reference implementation written at Xerox PARC. CMU CL's implementation of the LOOP macro was derived from code from Symbolics, which was derived from code from MIT. CMU CL had many individual author credits in the source files. In the sometimes-extensive rearrangements which were required to make SBCL bootstrap itself cleanly, it was tedious to try keep such credits attached to individual source files, so they have been moved here instead. William Harold Newman did this transformation, and so any errors made are probably his. Corrections would be appreciated. MORE DETAILS ON SBCL'S CLOS CODE The original headers of the PCL files contained the following text: ;;; Any person obtaining a copy of this software is requested to send their ;;; name and post office or electronic mail address to: ;;; CommonLoops Coordinator ;;; Xerox PARC ;;; 3333 Coyote Hill Rd. ;;; Palo Alto, CA 94304 ;;; (or send Arpanet mail to CommonLoops-Coordinator.pa@Xerox.arpa) ;;; ;;; Suggestions, comments and requests for improvements are also welcome. This was intended for the original incarnation of the PCL code as a portable reference implementation. Since our version of the code has had its portability hacked out of it, it's no longer particularly relevant to any coordinated PCL effort (which probably doesn't exist any more anyway). Therefore, this contact information has been deleted from the PCL file headers. A few files in the original CMU CL 18b src/pcl/ directory did not carry such Xerox copyright notices: * Some code was originally written by Douglas T. Crosher for CMU CL: ** the Gray streams implementation ** the implementation of DOCUMENTATION as methods of a generic function * generic-functions.lisp seems to have been machine-generated. The comments in the CMU CL 18b version of the PCL code walker, src/pcl/walk.lisp, said in part ;;; a simple code walker, based IN PART on: (roll the credits) ;;; Larry Masinter's Masterscope ;;; Moon's Common Lisp code walker ;;; Gary Drescher's code walker ;;; Larry Masinter's simple code walker ;;; . ;;; . ;;; boy, thats fair (I hope). MORE DETAILS ON SBCL'S LOOP CODE The src/code/loop.lisp file from CMU CL 18b had the following credits-related information in it: ;;; The LOOP iteration macro is one of a number of pieces of code ;;; originally developed at MIT for which free distribution has been ;;; permitted, as long as the code is not sold for profit, and as long ;;; as notification of MIT's interest in the code is preserved. ;;; ;;; This version of LOOP, which is almost entirely rewritten both as ;;; clean-up and to conform with the ANSI Lisp LOOP standard, started ;;; life as MIT LOOP version 829 (which was a part of NIL, possibly ;;; never released). ;;; ;;; A "light revision" was performed by me (Glenn Burke) while at ;;; Palladian Software in April 1986, to make the code run in Common ;;; Lisp. This revision was informally distributed to a number of ;;; people, and was sort of the "MIT" version of LOOP for running in ;;; Common Lisp. ;;; ;;; A later more drastic revision was performed at Palladian perhaps a ;;; year later. This version was more thoroughly Common Lisp in style, ;;; with a few miscellaneous internal improvements and extensions. I ;;; have lost track of this source, apparently never having moved it to ;;; the MIT distribution point. I do not remember if it was ever ;;; distributed. ;;; ;;; The revision for the ANSI standard is based on the code of my April ;;; 1986 version, with almost everything redesigned and/or rewritten. The date of the M.I.T. copyright statement falls around the time described in these comments. The dates on the Symbolics copyright statement are all later -- the earliest is 1989. MORE DETAILS ON OTHER SBCL CODE FROM CMU CL CMU CL's symbol (but not package) code (code/symbol.lisp) was originally written by Scott Fahlman and updated and maintained by Skef Wholey. The CMU CL reader (code/reader.lisp) was originally the Spice Lisp reader, written by David Dill and with support for packages added by Lee Schumacher. David Dill also wrote the sharpmacro support (code/sharpm.lisp). CMU CL's package code was rewritten by Rob MacLachlan based on an earlier version by Lee Schumacher. It also includes DEFPACKAGE by Dan Zigmond, and WITH-PACKAGE-ITERATOR written by Blaine Burks. William Lott also rewrote the DEFPACKAGE and DO-FOO-SYMBOLS stuff. CMU CL's string code (code/string.lisp) was originally written by David Dill, then rewritten by Skef Wholey, Bill Chiles, and Rob MacLachlan. Various code in the system originated with "Spice Lisp", which was apparently a predecessor to the CMU CL project. Much of that was originally written by Skef Wholey: code/seq.lisp, generic sequence functions, and COERCE code/array.lisp, general array stuff SXHASH code/list.lisp, list functions (based on code from Joe Ginder and Carl Ebeling) The CMU CL seq.lisp code also gave credits for later work by Jim Muller and Bill Chiles. The modules system (code/module.lisp, containing REQUIRE, PROVIDE, and friends, now deprecated by ANSI) was written by Jim Muller and rewritten by Bill Chiles. The CMU CL garbage collector was credited to "Christopher Hoover, Rob MacLachlan, Dave McDonald, et al." in the CMU CL code/gc.lisp file, with some extra code for the MIPS port credited to Christopher Hoover alone. Guy Steele wrote the original character functions code/char.lisp They were subsequently rewritten by David Dill, speeded up by Scott Fahlman, and rewritten without fonts and with a new type system by Rob MachLachlan. Lee Schumacher made the Spice Lisp version of backquote. The comment in the CMU CL sources suggests he based it on someone else's code for some other Lisp system, but doesn't say which. A note in the CMU CL code to pretty-print backquote expressions says that unparsing support was provided by Miles Bader. The CMU implementations of the Common Lisp query functions Y-OR-N-P and YES-OR-NO-P were originally written by Walter van Roggen, and updated and modified by Rob MacLachlan and Bill Chiles. The CMU CL sort functions (code/sort.lisp) were written by Jim Large, hacked on and maintained by Skef Wholey, and rewritten by Bill Chiles. Most of the internals of the Python compiler seem to have been originally written by Robert MacLachlan: the type system and associated "cold load hack magic" code/typedefs.lisp code/class.lisp code/type-init.lisp etc. the lexical environment database compiler/globaldb.lisp, etc. the IR1 representation and optimizer compiler/ir1*.lisp, etc. the IR2 representation and optimizer compiler/ir2*.lisp, etc. many concrete optimizations compiler/srctran.lisp (with some code adapted from CLC by Wholey and Fahlman) compiler/float-tran.lisp, etc. information about optimization of known functions compiler/fndb.lisp debug information representation compiler/debug.lisp, compiler/debug-dump.lisp memory pools to reduce consing by reusing compiler objects compiler/alloc.lisp toplevel interface functions and drivers compiler/main.lisp Besides writing the compiler, and various other work mentioned elsewhere, Robert MacLachlan was also credited with tuning the implementation of streams for Unix files, and writing various floating point support code code/float-trap.lisp, floating point traps code/float.lisp, misc. support a la INTEGER-DECODE-FLOAT low-level time functions code/time.lisp William Lott is also credited with writing or heavily maintaining some parts of the CMU CL compiler. He was responsible for lifting compiler/meta-vmdef.lisp out of compiler/vmdef.lisp, and also wrote various optimizations compiler/array-tran.lisp compiler/saptran.lisp compiler/seqtran.lisp (with some code adapted from an older seqtran written by Wholey and Fahlman) the separable compiler backend compiler/backend.lisp compiler/generic/utils.lisp the implementation of LOAD-TIME-VALUE compiler/ltv.lisp the most recent version of the assembler compiler/new-assem.lisp vop statistics gathering compiler/statcount.lisp centralized information about machine-dependent and.. ..machine-independent FOO, with compiler/generic/vm-fndb.lisp, FOO=function signatures compiler/generic/vm-typetran.lisp, FOO=type ops compiler/generic/objdef.lisp, FOO=object representation compiler/generic/primtype.lisp, FOO=primitive types Also, Christopher Hoover and William Lott wrote compiler/generic/vm-macs.lisp to centralize information about machine-dependent macros and constants. Sean Hallgren converted compiler/generic/primtype.lisp for the Alpha. The CMU CL machine-independent disassembler (compiler/disassem.lisp) was written by Miles Bader. Parts of the CMU CL system were credited to Skef Wholey and Rob MacLachlan jointly, perhaps because they were originally part of Spice Lisp and were then heavily modified: code/load.lisp, the loader, including all the FASL stuff code/macros.lisp, various fundamental macros code/mipsstrops.lisp, primitives for hacking strings code/purify.lisp, implementation of PURIFY code/stream.lisp, stream functions code/lispinit.lisp, cold startup code/profile.lisp, the profiler Bill Chiles also modified code/macros.lisp. Much of the implementation of PURIFY was rewritten in C by William Lott. The CMU CL number functions (code/number.lisp) were written by Rob MacLachlan, but acknowledge much code "derived from code written by William Lott, Dave Mcdonald, Jim Large, Scott Fahlman, etc." CMU CL's weak pointer support (code/weak.lisp) was written by Christopher Hoover. The CMU CL DEFSTRUCT system was credited to Rob MacLachlan, William Lott and Skef Wholey jointly. The FDEFINITION system for handling arbitrary function names (a la (SETF FOO)) was originally written by Rob MacLachlan. It was modified by Bill Chiles to add encapsulation, and modified more by William Lott to add FDEFN objects. The CMU CL condition system (code/error.lisp) was based on some prototyping code written by Ken Pitman at Symbolics. The CMU CL HASH-TABLE system was originally written by Skef Wholey for Spice Lisp, then rewritten by William Lott, then rewritten again by Douglas T. Crosher. The support code for environment queries (a la LONG-SITE-NAME), the DOCUMENTATION function, and the DRIBBLE function was written and maintained "mostly by Skef Wholey and Rob MacLachlan. Scott Fahlman, Dan Aronson, and Steve Handerson did stuff here too." The same credit statement was given for the original Mach OS interface code. The CMU CL printer, print.lisp, was credited as "written by Neal Feinberg, Bill Maddox, Steven Handerson, and Skef Wholey, and modified by various CMU Common Lisp maintainers." The comments in the main body of the CMU CL debugger code/debug.lisp say that it was written by Bill Chiles. Some other related files code/debug-int.lisp, programmer's interface to the debugger code/ntrace.lisp, tracing facility based on breakpoints say they were written by Bill Chiles and Rob MacLachlan. The related file src/debug-vm.lisp, low-level support for :FUNCTION-END breakpoints was written by William Lott. The CMU CL GENESIS cold load system, compiler/generic/new-genesis.lisp, was originally written by Skef Wholey, then jazzed up for packages by Rob MacLachlan, then completely rewritten by William Lott for the MIPS port. The CMU CL IR1 interpreter was written by Bill Chiles and Robert MacLachlan. Various CMU CL support code was written by William Lott: the bytecode interpreter code/byte-interp.lisp bitblt-ish operations a la SYSTEM-AREA-COPY code/bit-bash.lisp Unix interface code/fd-stream.lisp, Unix file descriptors as Lisp streams code/filesys.lisp, other Unix filesystem interface stuff handling errors signalled from assembly code code/interr.lisp compiler/generic/interr.lisp finalization based on weak pointers code/final.lisp irrational numeric functions code/irrat.lisp the pretty printer code/pprint.lisp predicates (both type predicates and EQUAL and friends) code/pred.lisp saving the current Lisp image as a core file code/save.lisp handling Unix signals code/signal.lisp implementing FORMAT code/format.lisp The ALIEN facility seems to have been written largely by Rob MacLachlan and William Lott. The CMU CL comments say "rewritten again, this time by William Lott and Rob MacLachlan," but don't identify who else might have been involved in earlier versions. The comments in CMU CL's code/final.lisp say "the idea really was Chris Hoover's". The comments in CMU CL's code/pprint.lisp say "Algorithm stolen from Richard Waters' XP." The comments in CMU CL's code/format.lisp say "with lots of stuff stolen from the previous version by David Adam and later rewritten by Bill Maddox." Jim Muller was credited with fixing seq.lisp. CMU CL's time printing logic, in code/format-time.lisp, was written by Jim Healy. Bill Chiles was credited with fixing/updating seq.lisp after Jim Muller. The CMU CL machine/filesystem-independent pathname functions (code/pathname.lisp) were written by William Lott, Paul Gleichauf, and Rob MacLachlan, based on an earlier version written by Jim Large and Rob MacLachlan. Besides writing the original versions of the things credited to him above, William Lott rewrote, updated, and cleaned up various stuff: code/array.lisp code/serve-event.lisp The INSPECT function was originally written by Blaine Burks. The CMU CL DESCRIBE facility was originally written by "Skef Wholey or Rob MacLachlan", according to the comments in the CMU CL sources. It was cleaned up and reorganized by Blaine Burks, then ported and cleaned up more by Rob MacLachlan. Also, since the split from CMU CL, the SBCL DESCRIBE facility was rewritten as a generic function and so become entangled with some DESCRIBE code which was distributed as part of PCL. The implementation of the Mersenne Twister RNG used in SBCL is based on an implementation written by Douglas T. Crosher and Raymond Toy, which was placed in the public domain with permission from M. Matsumoto. Comments in the CMU CL version of FreeBSD-os.c said it came from an OSF version by Sean Hallgren, later hacked by Paul Werkowski, with generational conservative GC support added by Douglas Crosher. Comments in the CMU CL version of linux-os.c said it came from the FreeBSD-os.c version, morfed to Linux by Peter Van Eynde in July 1996. Comments in the CMU CL version of backtrace.c said it was "originally from Rob's version" (presumably Robert Maclachlan). Comments in the CMU CL version of purify.c said it had stack direction changes, x86/CGC stack scavenging, and static blue bag stuff (all for x86 port?) by Paul Werkowski, 1995, 1996; and bug fixes, x86 code movement support, and x86/gencgc stack scavenging by Douglas Crosher, 1996, 1997, 1998. According to comments in the source files, much of the CMU CL version of the x86 support code assembly/x86/alloc.lisp assembly/x86/arith.lisp assembly/x86/array.lisp assembly/x86/assem-rtns.lisp compiler/x86/alloc.lisp compiler/x86/arith.lisp compiler/x86/c-call.lisp compiler/x86/call.lisp compiler/x86/cell.lisp compiler/x86/char.lisp compiler/x86/debug.lisp compiler/x86/float.lisp compiler/x86/insts.lisp compiler/x86/macros.lisp compiler/x86/memory.lisp compiler/x86/move.lisp compiler/x86/nlx.lisp compiler/x86/parms.lisp compiler/x86/pred.lisp compiler/x86/print.lisp compiler/x86/sap.lisp compiler/x86/static-fn.lisp compiler/x86/subprim.lisp compiler/x86/system.lisp compiler/x86/type-vops.lisp compiler/x86/values.lisp compiler/x86/vm.lisp was originally written by William Lott, then debugged by Paul Werkowski, and in some cases later enhanced and further debugged by Douglas T. Crosher; and the x86 runtime support code, x86-assem.S was written by Paul F. Werkowski and Douglas T. Crosher. The CMU CL user manual (doc/cmu-user/cmu-user.tex) says that the X86 FreeBSD port was originally contributed by Paul Werkowski, and Peter VanEynde took the FreeBSD port and created a Linux version. According to comments in src/code/bsd-os.lisp, work on the generic BSD port was done by Skef Wholey, Rob MacLachlan, Scott Fahlman, Dan Aronson, and Steve Handerson. Douglas Crosher wrote code to support Gray streams, added X86 support for the debugger and relocatable code, wrote a conservative generational GC for the X86 port, and added X86-specific extensions to support stack groups and multiprocessing. The CMU CL user manual credits Robert MacLachlan as editor. A chapter on the CMU CL interprocess communication extensions (not supported in SBCL) was contributed by William Lott and Bill Chiles. Peter VanEynde also contributed a variety of #+HIGH-SECURITY patches to CMU CL, to provide additional safety, especially through runtime checking on various tricky cases of standard functions (e.g. MAP with complicated result types, and interactions of various variants of STREAM). Raymond Toy wrote the propagate-float-type extension and various other floating point optimizations. CMU CL's long float support was written by Douglas T. Crosher. Paul Werkowski turned the Mach OS support code into Linux OS support code. Versions of the RUN-PROGRAM extension were written first by David McDonald, then by Jim Healy and Bill Chiles, then by William Lott. MORE DETAILS ON THE TRANSITION FROM CMU CL Bill Newman did the original conversion from CMU CL 18b to a form which could bootstrap itself cleanly, on Linux/x86 only. Although they may not have realized it at the time, Rob Maclachlan and Peter Van Eynde were very helpful, RAM by posting a clear explanation of what GENESIS is supposed to be doing and PVE by maintaining a version of CMU CL which worked on Debian, so that I had something to refer to whenever I got stuck. CREDITS SINCE THE RELEASE OF SBCL Martin Atzmueller: He reported many bugs in SBCL, helped clean up various stale bug data in SBCL, and ported many patches from CMU CL. Daniel Barlow: He contributed sblisp.lisp, a set of patches to make SBCL play nicely with ILISP. (Those patches have since disappeared from the SBCL distribution because ILISP has since been patched to play nicely with SBCL.) He also figured out how to get the CMU CL dynamic object file loading code to work under SBCL. Cadabra, Inc.: They hired William Newman to do some consulting for them, including the implementation of EQUALP hash tables for CMU CL; then agreed to release the EQUALP code into the public domain, giving SBCL, and CMU CL, EQUALP hash tables. Douglas Crosher: He continued to improve CMU CL after SBCL forked from it, creating many patches which were directly applicable to SBCL. Notable examples include fixes for various compiler bugs, and a generalization of the type system's handling of the CONS type to allow ANSI-style (CONS FOO BAR) types. Robert MacLachlan: He has continued to answer questions about, and contribute fixes to, the CMU CL project. Some of these fixes, especially for compiler problems, has been invaluable to the CMU CL project and, by porting, invaluable to the SBCL project as well. Peter Van Eynde: He wrestled the CLISP test suite into a portable test suite which can be used on SBCL, and submitted many other bug reports as well. Colin Walters: His O(N) implementation of the general case of MAP, posted on the cmucl-imp@cons.org mailing list, was the inspiration for similar MAP code added in sbcl-0.6.8. Raymond Wiker: He ported sbcl-0.6.3 back to FreeBSD, restoring the ancestral CMU CL support for FreeBSD and updating it for the changes made from FreeBSD version 3 to FreeBSD version 4. He also ported the CMU CL extension RUN-PROGRAM, and related code, to SBCL.