cforth

I got a quick reply from Mitch Bradley! Yes I wrote a paper but I probably can't find it. The easiest place to look would be in the Open Firmware source. https://github.com/MitchBradley/openfirmware/blob/master/for... The magic is all in +level and -level. Search for those in kernel.fth to see other places they are used to achieve a similar effect, e.g. in abort" For an alternative but effectively equivalent formulation, see: https://github.com/MitchBradley/cforth/blob/master/src/cfort... and https://github.com/MitchBradley/cforth/blob/master/src/cfort... [...] https://news.ycombinator.com/item?id=29264309 In PostScript that would be: /PostScript Know? { Honk! } { /PostScript Learn! } ifelse FORTH doesn't have an IFELSE unless you define it yourself of course, but it would have no way of telling which part of your code was the conditional, part to do if true, or part to do if false, since white space and line breaks have no meaning to it, except for a few cases like \ comments. The IF comes between the conditional and the part to do if true, the ELSE comes between the part to do if true and the part to do if false, and the THEN comes at the end. The structure of PostScript code, conditionals, and flow control is homoiconic, made of nested arrays, like polymorphic JSON arrays, where FORTH code is flat untyped arrays of threaded pointers with relative branching. Forth has an "inner interpreter" called NEXT that threads from one pointer to the next (sometimes implemented as one machine language instruction, or just a few), and also an "outer interpreter" or compiler that translates text into threaded code for the inner interpreter. https://en.wikipedia.org/wiki/Polymorphism_(computer_science... https://en.wikipedia.org/wiki/Homoiconicity https://en.wikipedia.org/wiki/Threaded_code Here's Mitch Bradley's implementation of interactive control structures (IF, ELSE, THEN, BEGIN, UNTIL, AGAIN, REPEAT, WHILE, DO, LOOP, etc) in the outer interpreter of his FORTH system, which actually allows you to use conditionals and loops at the interactive top level of the interpreter, not just in compiled words (which solves a traditional and frustrating limitation of classic FORTH). https://github.com/MitchBradley/openfirmware/blob/master/for... Here is an alternative but equivalent implementation of interactive Forth control structures in his CForth (Forth implemented in C, of course): https://github.com/MitchBradley/cforth/blob/master/src/cfort... Here's some more of Mitch's beautiful code from OpenFirmware, his Forth kernel meta-compiler written in Forth, which supports 8, 16, 32, an 64 bit, big-endian and little-endian architectures, as well as direct, indirect, and token threaded code: https://github.com/MitchBradley/openfirmware/blob/master/for... https://en.wikipedia.org/wiki/Threaded_code#Direct_threading https://en.wikipedia.org/wiki/Threaded_code#Indirect_threadi... https://en.wikipedia.org/wiki/Threaded_code#Token_threading [...] https://news.ycombinator.com/item?id=29265144 Some FORTH systems even have a "metacompiler" that lets one FORTH system compile another FORTH system for the same or different CPU, word size, byte order, threading technique, with or without a built-in compiler, etc, from the same source code! OpenFirmware (the FORTH burnt into boot roms of SPARC, PowerPC, OLPC, and other systems) is a great highly refined example that supports many different architectures: openfirmware/forth/kernel/metacompile.fth https://github.com/openbios/openfirmware/blob/master/forth/k... openfirmware/forth/kernel/meta1.fth https://github.com/openbios/openfirmware/blob/master/forth/k... The OpenFirmware kernel is a Forth meta-compiler, which can compile itself on any architecture, and also cross-compile for different target architectures. It has cross-architecture extensions to FORTH (like \16 \32 comments and /n /n* generically typed words) that make it possible to write platform, word size, byte order, and threading independent code, and compile images (stripped or with headers) for embedded systems (like the OLPC boot ROMs) and new CPU architectures (like Sun's transition from 68K to SPARC), and share code with a more powerful development environments. https://en.wikipedia.org/wiki/Compiler-compiler#Forth_metaco... [...] https://news.ycombinator.com/item?id=29264489 [...] Here's some IBM-PC Forth for the CAM-6 cellular automata machine that was block based -- check out the unique idiosyncratic right-justified reverse-indentation style (starting with KGET), which is not standard Forth style, but sure looks cool and poetic, like E E CUMMINGS ON CAPS LOCK: https://donhopkins.com/home/code/tomt-cam-forth-scr.txt https://donhopkins.com/home/code/tomt-users-forth-scr.txt [...] https://news.ycombinator.com/item?id=29261868 Coco Conn and Paul Rother wrote this up about what they did with FORTH at HOMER & Assoc, who made some really classic music videos including Atomic Dog, and hired Charles Moore himself! Here's what Coco Conn posted about it, and some discussion and links about it that I'm including with her permission: [...] Forth & Charles Moore We hired Forth, Inc. and got Charles Moore, the inventor of FORTH to program the console host computer. I learned FORTH and worked with Charles. I programmed the 2K byte EPROM in each visual channel. On the Master Z80 system we ran PolyForth a multi tasking system in 32K bytes. We had an extra 16K RAM for buffers and things. If I remember right, the system ran four tasks, but that was 20 years ago, my memory may be hazy. Anyway, I learn not only FORTH from Charles Moore, but also how to factor code in to small reusable routines, WORDs they're called in FORTH. I learned Object Oriented Programming without knowing it. Also a lot of use of vectors. Its a cool language. Charles Moore was a great inspiration to me, and really taught me a great deal that they never taught me in computer programming school. [...]

rmware, portable device drivers, hardware and driver configuration, and many hardware platforms. https://github.com/MitchBradley/openfirmware This is an implementation of Open Firmware, a processor-independent firmware design. Open Firmware is specified by IEEE 1275-1994, Standard for Boot (Initialization, Configuration) Firmware. The IEEE standard designation lapsed in 1999, when the Open Firmware working group declined to go through the rather time-consuming IEEE reaffirmation process, but the design lives on. This implementation was written primarily by Mitch Bradley, the original author of Open Firmware. The bulk of the recent development was done at Firmworks by Bradley and colleagues. It traces its roots back to the original Open Boot firmware implementation that Bradley developed at Sun Microsystems in the late 80s and early 90s. That in turn had roots in Forthmacs, a Forth programming language implementation developed and marketed during the early 80s by Bradley Forthware. And Forthmacs, in turn, owes a debt of gratitude to the public domain Forth implementations F83, developed by Michael Perry, and MVP Forth, by Glen Haydon. Lilian Walter wrote the USB stack. https://news.ycombinator.com/item?id=29279022 DonHopkins on Nov 19, 2021 | parent | context | favorite | on: Forth vs Lisp The inner interpreter of Mitch Bradley's portable and efficient CForth is simply implemented with a big switch statement, in the function called "inner_interpreter". The C compiler typically compiles that code with the big switch statement into an efficient jump table, behind the scenes. https://github.com/MitchBradley/cforth/blob/master/src/cfort... Properly speaking, that's a token threaded interpreter, since it switches on token numbers in the code field, instead of indirecting function through pointers to the C equivalent of "code" words. https://en.wikipedia.org/wiki/Threaded_code#Token_threading https://news.ycombinator.com/item?id=27484426 DonHopkins on June 12, 2021 | root | parent | next [–] From https://news.ycombinator.com/item?id=21823081 I wrote malloc.fth for Mitch Bradley's ForthMacs, which ended up in OpenFirmware: https://github.com/openbios/openfirmware/blob/master/ofw/cor... [...] https://news.ycombinator.com/item?id=21822840 DonHopkins on Dec 18, 2019 | parent | context | favorite | on: Thoughts on Forth Programming Here's the interview with Mitch Bradley saved on archive.org: https://web.archive.org/web/20120118132847/http://howsoftwar... I've previously posted some stuff about Mitch Bradley -- I have used various versions of his ForthMacs / CForth / OpenFirmware systems, and I was his summer intern at Sun in '87! Mitch is an EXTREMELY productive FORTH programmer! He explains that FORTH is a "Glass Box": you just have to memorize its relatively simple set of standard words, and then you can have a complete understanding and full visibility into exactly how every part of the system works: there is no mysterious "magic", you can grok and extend every part of the system all the way down to the metal. It's especially nice when you have a good decompiler / dissassembler ("SEE") like ForthMacs, CForth, and OpenFirmware do. https://news.ycombinator.com/item?id=9271644 [...]