I believe the reason I did all the stack juggling was because I wanted to write it "the Forth way", or maybe the "pure stack-based way", and using variables seemed like cheating.
I certainly won't be pursuing this further (I wrote it 20 years ago as a programming exercise), but I hope somebody will learn from your exposition :-)
I think "using variables seemed like cheating" was a lot of my motivation, too, and it led me into a great deal of mischief. Despite what I thought at first, I think "the Forth way" does use variables pretty often, although I guess different people's "Forth way" is different. But consider Chuck Moore's Forth Way:
> A Forth word should not have more than one or two arguments. This stack which people have so much trouble manipulating should never be more than three or four deep. ... But as to stack parameters, the stacks should be shallow. On the i21 we have an on-chip stack 18 deep. This size was chosen as a number effectively infinite.
> The words that manipulate that stack are DUP, DROP and OVER period. There's no ..., well SWAP is very convenient and you want it, but it isn't a machine instruction. But no PICK[,] no ROLL, none of the complex operators to let you index down into the stack. This is the only part of the stack, these first two elements, that you have any business worrying about.
> The others are on the stack because you put them there and you are going to use them later after the stack falls back to their position. They are not there because [you're] using them now. You don't want too many of those things on the stack because you are going to forget what they are.
> So people who draw stack diagrams or pictures of things on the stack should immediately realize that they are doing something wrong. Even the little parameter pictures that are so popular. You know if you are defining a word and then you put in a comment showing what the stack effects are and it indicates F and x and y
F ( x - y )
— http://www.ultratechnology.com/1xforth.htm
I was trying to find the "sheesh, just use a variable" quote I seem to remember from him, but I can't find it. Maybe I'm inadvertently attributing my own ideas to him. But if you look at his code (there are some excerpts in http://www.ultratechnology.com/fsc98.htm and http://www.ultratechnology.com/tape1.htm) you'll see he's pretty sparing with stack operations and uses variables (in memory) pretty regularly.
Certainly my recommendation here—start with statements and expressions, use lots of variables—differs from, say, Jeff Fox's recommendation. And I'm pretty sure Jeff Fox was a better Forth programmer than I am. And I think it's common that, with enough thought, you can find a better way to design the code that reduces the amount of state you have to keep at memory addresses. But I think a programmer already experienced in another language is much more likely to shoot herself in the foot in Forth by using too many stack operations and too many values on the stack, than by using too many variables, so I think it's probably a better learning path.
(FWIW, I think the advice to not write stack comments is probably bad advice, even though Chuck Moore was and probably is a much better Forth programmer than I am.)
Also, though, and I feel like I should have emphasized this more from the outset, I have never shipped code to users in Forth. In fact, I don't even have any personal utility programs written in Forth. That's because I still find Forth hard to read, write, and debug, despite being fascinated with it for 25 years. I think my motivation for writing the above readprint.fs code was to sort of see how terrible I was at writing Forth (answer: it took me 2 hours to write 30 lines of code, so still pretty terrible, but at least I did manage to write a working parser.) So please take my opinions on the matter with a grain of salt.
It's not strictly about Lisp; Perlis was fond of Lisp but his true love was APL. But you could use it to advocate JSON, bytestream shell pipelines, or even TCP/IP. Or a flat byte-addressable memory, I suppose, like Forth or amd64.
Are you thinking of something like the static typing system of Christopher Diggins's "Cat" language, or its children Kitten and Mlatu?
While those are interesting, probably in the same way that Shen is interesting, I was thinking more along the lines that stack is an open ended product type (I made that up) and that operations on the stack are like a zipper, map, fold, product. That there is a projectional aspect to the stack, its expansion and contraction and shape over time.
The engines that do protein folding feel like they have similarities.
I still haven't grokked your whole description of your Lisp reader, I'll have to sleep on it. Is it related in structure to the METAII meta compiler or parser combinators?
popop = { pop pop}
popop : ('t0 't1 't2 -> 't2)
Not sure what you mean about "projectional" — do you mean that "pop" is a "projection" in the relational sense, in that it maps, for example, the stack 3 8 1 (with the top on the left) and the stack 7 8 1 to the same resulting stack state 8 1?
I don't know anything about protein folding.
> I still haven't grokked your whole description of your Lisp reader, I'll have to sleep on it. Is it related in structure to the METAII meta compiler or parser combinators?
Well, I didn't really write much of a description of the reader. It's a recursive-descent predictive parser, same as Probst's reader, and probably most Lisp readers. READ sets up the input pointers and calls (READ), which is ((READ)), which discriminates between lists and atoms (which are numbers) by looking for a "(". If it doesn't find one, it calls READ-NUM to read a number. But if it does, it calls READ-TAIL, which recursively reads the list contents (by calling (READ)) until it finds a ")", then returns back up, consing up the list as it goes. Probst's code works the same way, with the correspondences READ ↔ LISP-LOAD-FROM-STRING, (READ) ↔ LISP-READ-LISP, ((READ)) ↔ _LISP-READ-LISP, READ-NUM ↔ LISP-READ-TOKEN/-NUMBER/-SYMBOL, and READ-TAIL ↔ LISP-READ-LIST.
META II has the similarity that it generates recursive-descent parsers with predictive parsing, but the dissimilarity that it's a domain-specific language for writing parsers. Parser combinators are a technique for embedding any domain-specific parsing language in a general-purpose host language, regardless of what parsing algorithm is used, though Packrat may be the most common choice, and Packrat has certain similarities to recursive-descent parsing.
Is that helpful?
Forth:
: droop drop drop ;
: drooop drop drop drop ;
: droooop drop drop drop drop ;
/poop { pop pop } def
/pooop { pop pop pop } def
/poooop { pop pop pop pop } defThen after things were working they might replace droooop with something like this:
( Forth assembler psuedo-code follows)
code droooop sp 4 cells addi, next, endcode
*Next, is the traditional name of the "return to Forth function" in threaded Forth. A return instruction would be used in a native code Forth. Carnal knowledge of the internals is required and used by Forth coders.
Here's some Breshenham line code I first wrote in FORTH (Mitch Bradley's SunForth on a 68k Sun-2 with cg2 graphics board), then translated to 68k code (using the rpn FORTH assembler) -- the FORTH code is commented out before the corresponding assembly code:
https://donhopkins.com/home/archive/forth/cg/line.f
The cg2 board wasn't directly memory mapped -- it had a really weird way of selecting and accessing one row and one column at a time, which was kinda convenient for drawing lines and curves, and ropping blocks around, but nowhere as convenient as direct memory mapped access would have been.
https://donhopkins.com/home/archive/forth/cg/cg.f
I had to reverse engineer it from the map of the registers in this helpful include file:
https://donhopkins.com/home/archive/forth/cg/cg2reg.h
* To save on virtual address space, we don't map the plane or pixel mode
* memory (first two megabytes). However, when calling mmap the user has
* to add 2M to the desired offset anyway (goofy, huh?).Why were you in 640×480? I thought the cgtwo was 1152×900 like God intended, and that's what the .h says too.
Was the reason it was important to save virtual address space important that the 68010 ignored the upper 8 bits of virtual addresses? (Helllo, pointer typetag...)
The assembler looks pretty pleasant, though all the 68k operand size suf-, uh, prefixes make the code a bit LONGer than it could be. In gas I really miss having a macro system that can express nested control structures (so I guess I should quit my bitching and write one and use it). I suppose the tests for the IF and WHILE are limited to <, =, <>, >, 0<, 0>, and 0<>?
I'm curious what you think of my analogy upthread between stack-manipulation words and goto. Does it reflect your experience? I'd forgotten you'd done a bunch of Forth stuff.
That particular assembler had structured control flow like if, while, etc.
It might have actually been a cgone, since the device name was /dev/cgone0. But the header file said cg2. Whatever it was, it was quite slow!
Years later, John Gilmore mentioned that he wrote that .h file with the C structures/unions that mapped out all the device registers.
I bought a copy of Aviator by Curt Priem and Bruce Factor, that ran on my SS2 pizzabox's GX "LEGO: Low End Graphics Option" SBus card (an 8 bit color + 2 bits monochrome overlay plane graphics accelerator):
https://techmonitor.ai/techonology/aviator_15_for_sun_networ...
>AVIATOR 1.5 FOR SUN NETWORKS OPENS UP GRAPHICS WORKSTATION GAMES MARKET. By CBR Staff Writer, 08 Jul 1991.
Not sure why the memory mapping was so weird -- but at least it wasn't as bizarre as the Apple ][! It did have some weird undocumented limitations, like you could only write to the colormap during vertical retrace (which I discovered the hard way -- it didn't seem to work for no apparent reason, except for the occasional times when it did kinda work).
Here's a reference to the cgone device that sounds about right:
http://ftp.uni-bayreuth.de/Digital/alphaserver/archive/magic...
* SUN120 A Sun Microsystems workstation, model Sun2/120 with
* a separate colorboard (/dev/cgone0) and the
* Sun optical mouse. Also works on some old Sun1s with
* the 'Sun2 brain transplant'.
Frame Buffer History Lesson
Last Updated: 24th November 1998
cg1/bw1: device name : "/dev/cgoneX" "/dev/bwoneX"
The color and monochrome framebuffer of sun100u.
It is not a crime not knowing anything about these. (and this was 7 years ago!)If you really wanted to provide such a set of operators for, say, the top N stack items, you could give them systematic names with some distinctive scheme; limiting such stack operators to the top 3, for example, with no more than 2 extra results, you could provide the operators x→ (drop), x→x (nop), x→xx (bad Mexican beer), x→xxx (dupup), xy→ (2drop), xy→x (nip), xy→y (drop again, for consistency), xy→xx (nip dup), xy→xy (nop), xy→yx (exch†), xy→yy (drop dup), xy→xxx (nip dup dup), xy→xxy (dup again), xy→xyx (tuck), xy→xyy, xy→yxx, xy→yxy, xy→yyx, xy→yyy, xy→xxxx, xy→xxxy, xy→xxyx, xy→xxyy, xy→xyxx, xy→xyxy, xy→xyyx, xy→xyyy, xy→yxxx, xy→yxxy, xy→yxyx, xy→yxyy, xy→yyxx, xy→yyxy, xy→yyyx, xy→yyyy, xyz→, xyz→x, xyz→y, xyz→z, xyz→xx, xyz→xy (condescending answer on Stack Overflow), xyz→xz, xyz→yx, xyz→yy, xyz→yz, xyz→zx, xyz→zy, xyz→zz, xyz→xxx (programmers over 18 only), xyz→xxy (Klinefelter syndrome), xyz→xxz, xyz→xyx, xyz→xyy (Jacobs syndrome), xyz→xyz, xyz→xzx, xyz→xzy, xyz→xzz, xyz→yxx, xyz→yxy, xyz→yxz, xyz→yyx, xyz→yyy (bargaining, denial), xyz→yyz, xyz→yzx, xyz→yzy, xyz→yzz, xyz→zxx, xyz→zxy, xyz→zxz, xyz→zyx, xyz→zyy, xyz→zyz, xyz→zzx, xyz→zzy, xyz→zzz, xyz→xxxx, xyz→xxxy, xyz→xxxz, xyz→xxyx, xyz→xxyy, xyz→xxyz, xyz→xxzx, xyz→xxzy, xyz→xxzz, xyz→xyxx, xyz→xyxy, xyz→xyxz, xyz→xyyx, xyz→xyyy, xyz→xyyz, xyz→xyzx, xyz→xyzy, xyz→xyzz, xyz→xzxx, xyz→xzxy, xyz→xzxz, xyz→xzyx, xyz→xzyy, xyz→xzyz, xyz→xzzx, xyz→xzzy, xyz→xzzz, xyz→yxxx, xyz→yxxy, xyz→yxxz, xyz→yxyx, xyz→yxyy, xyz→yxyz, xyz→yxzx, xyz→yxzy, xyz→yxzz, xyz→yyxx, xyz→yyxy, xyz→yyxz, xyz→yyyx, xyz→yyyy, xyz→yyyz, xyz→yyzx, xyz→yyzy, xyz→yyzz, xyz→yzxx, xyz→yzxy, xyz→yzxz, xyz→yzyx, xyz→yzyy, xyz→yzyz, xyz→yzzx, xyz→yzzy, xyz→yzzz, xyz→zxxx, xyz→zxxy, xyz→zxxz, xyz→zxyx, xyz→zxyy, xyz→zxyz, xyz→zxzx, xyz→zxzy, xyz→zxzz, xyz→zyxx, xyz→zyxy, xyz→zyxz, xyz→zyyx, xyz→zyyy, xyz→zyyz, xyz→zyzx, xyz→zyzy, xyz→zyzz, xyz→zzxx, xyz→zzxy, xyz→zzxz, xyz→zzyx, xyz→zzyy, xyz→zzyz, xyz→zzzx, xyz→zzzy, xyz→zzzz (sleep 4), xyz→xxxxx, xyz→xxxxy, xyz→xxxxz, xyz→xxxyx, xyz→xxxyy, xyz→xxxyz, xyz→xxxzx, xyz→xxxzy, xyz→xxxzz, xyz→xxyxx, xyz→xxyxy, xyz→xxyxz, xyz→xxyyx, xyz→xxyyy, xyz→xxyyz, xyz→xxyzx, xyz→xxyzy, xyz→xxyzz, xyz→xxzxx, xyz→xxzxy, xyz→xxzxz, xyz→xxzyx, xyz→xxzyy, xyz→xxzyz, xyz→xxzzx, xyz→xxzzy, xyz→xxzzz, xyz→xyxxx, xyz→xyxxy, xyz→xyxxz, xyz→xyxyx, xyz→xyxyy, xyz→xyxyz, xyz→xyxzx, xyz→xyxzy, xyz→xyxzz, xyz→xyyxx, xyz→xyyxy, xyz→xyyxz, xyz→xyyyx, xyz→xyyyy, xyz→xyyyz, xyz→xyyzx, xyz→xyyzy, xyz→xyyzz, xyz→xyzxx, xyz→xyzxy, xyz→xyzxz, xyz→xyzyx, xyz→xyzyy, xyz→xyzyz, xyz→xyzzx, xyz→xyzzy (Nothing happens), xyz→xyzzz, xyz→xzxxx, xyz→xzxxy, xyz→xzxxz, xyz→xzxyx, xyz→xzxyy, xyz→xzxyz, xyz→xzxzx, xyz→xzxzy, xyz→xzxzz, xyz→xzyxx, xyz→xzyxy, xyz→xzyxz, xyz→xzyyx, xyz→xzyyy, xyz→xzyyz, xyz→xzyzx, xyz→xzyzy, xyz→xzyzz, xyz→xzzxx, xyz→xzzxy, xyz→xzzxz, xyz→xzzyx, xyz→xzzyy, xyz→xzzyz, xyz→xzzzx, xyz→xzzzy, xyz→xzzzz, xyz→yxxxx, xyz→yxxxy, xyz→yxxxz, xyz→yxxyx, xyz→yxxyy, xyz→yxxyz, xyz→yxxzx, xyz→yxxzy, xyz→yxxzz, xyz→yxyxx, xyz→yxyxy, xyz→yxyxz, xyz→yxyyx, xyz→yxyyy, xyz→yxyyz, xyz→yxyzx, xyz→yxyzy, xyz→yxyzz, xyz→yxzxx, xyz→yxzxy, xyz→yxzxz, xyz→yxzyx, xyz→yxzyy, xyz→yxzyz, xyz→yxzzx, xyz→yxzzy, xyz→yxzzz, xyz→yyxxx, xyz→yyxxy, xyz→yyxxz, xyz→yyxyx, xyz→yyxyy, xyz→yyxyz, xyz→yyxzx, xyz→yyxzy, xyz→yyxzz, xyz→yyyxx, xyz→yyyxy, xyz→yyyxz, xyz→yyyyx, xyz→yyyyy, xyz→yyyyz, xyz→yyyzx, xyz→yyyzy, xyz→yyyzz, xyz→yyzxx, xyz→yyzxy, xyz→yyzxz, xyz→yyzyx, xyz→yyzyy, xyz→yyzyz, xyz→yyzzx, xyz→yyzzy, xyz→yyzzz, xyz→yzxxx, xyz→yzxxy, xyz→yzxxz, xyz→yzxyx, xyz→yzxyy, xyz→yzxyz, xyz→yzxzx, xyz→yzxzy, xyz→yzxzz, xyz→yzyxx, xyz→yzyxy, xyz→yzyxz, xyz→yzyyx, xyz→yzyyy, xyz→yzyyz, xyz→yzyzx, xyz→yzyzy, xyz→yzyzz, xyz→yzzxx, xyz→yzzxy, xyz→yzzxz, xyz→yzzyx, xyz→yzzyy, xyz→yzzyz, xyz→yzzzx, xyz→yzzzy, xyz→yzzzz, xyz→zxxxx, xyz→zxxxy, xyz→zxxxz, xyz→zxxyx, xyz→zxxyy, xyz→zxxyz, xyz→zxxzx, xyz→zxxzy, xyz→zxxzz, xyz→zxyxx, xyz→zxyxy, xyz→zxyxz, xyz→zxyyx, xyz→zxyyy, xyz→zxyyz, xyz→zxyzx, xyz→zxyzy, xyz→zxyzz, xyz→zxzxx, xyz→zxzxy, xyz→zxzxz, xyz→zxzyx, xyz→zxzyy, xyz→zxzyz, xyz→zxzzx, xyz→zxzzy, xyz→zxzzz, xyz→zyxxx, xyz→zyxxy, xyz→zyxxz, xyz→zyxyx, xyz→zyxyy, xyz→zyxyz, xyz→zyxzx, xyz→zyxzy, xyz→zyxzz, xyz→zyyxx, xyz→zyyxy, xyz→zyyxz, xyz→zyyyx, xyz→zyyyy, xyz→zyyyz, xyz→zyyzx, xyz→zyyzy, xyz→zyyzz, xyz→zyzxx, xyz→zyzxy, xyz→zyzxz, xyz→zyzyx, xyz→zyzyy, xyz→zyzyz, xyz→zyzzx, xyz→zyzzy, xyz→zyzzz, xyz→zzxxx, xyz→zzxxy, xyz→zzxxz, xyz→zzxyx, xyz→zzxyy, xyz→zzxyz, xyz→zzxzx, xyz→zzxzy, xyz→zzxzz, xyz→zzyxx, xyz→zzyxy, xyz→zzyxz, xyz→zzyyx, xyz→zzyyy, xyz→zzyyz, xyz→zzyzx (Soda Springs), xyz→zzyzy, xyz→zzyzz, xyz→zzzxx, xyz→zzzxy, xyz→zzzxz, xyz→zzzyx, xyz→zzzyy, xyz→zzzyz, xyz→zzzzx, xyz→zzzzy, and xyz→zzzzz. You could certainly argue about the utility of many of these operators individually, not to say their mental risk as attractive nuisances, but their mnemonic value is indisputable.
______
† Where do you get an old PostScript printer? At an exch meet.
: NOP DUP SWAP DROP ;
Also:
Q: How many Northern Californians does it take to change a lightbulb?
A: Hella!!!
Q: How many Southern Californians does it take to change a lightbulb?
A: Totally!!!
https://escholarship.org/uc/item/6492j904
http://people.duke.edu/~eec10/hellanorcal.pdf
Hella Nor Cal or Totally So Cal?: The Perceptual Dialectology of California
Mary Bucholtz, Nancy Bermudez, Victor Fung, Lisa Edwards and Rosalva Vargas. Journal of English Linguistics 2007; 35; 325. DOI: 10.1177/0075424207307780
>Abstract
>This study provides the first detailed account of perceptual dialectology within California (as well as one of the first accounts of perceptual dialectology within any single state). Quantitative analysis of a map-labeling task carried out in Southern California reveals that California’s most salient linguistic boundary is between the northern and southern regions of the state. Whereas studies of the perceptual dialectology of the United States as a whole have focused almost exclusively on regional dialect differences, respondents associated particular regions of California less with distinctive dialects than with differences in language (English versus Spanish), slang use, and social groups. The diverse socio linguistic situation of California is reflected in the emphasis both on highly salient social groups thought to be stereotypical of California by residents and nonresidents alike (e.g., surfers) and on groups that, though prominent in the cultural landscape of the state, remain largely unrecognized by outsiders (e.g., hicks).
Extra credit question:
Can you locate the isogloss designating the "101" / "The 101" line?
https://en.wikipedia.org/wiki/Isogloss
https://www.youtube.com/watch?v=zIklKPzND20&ab_channel=Satur...
OVER SWAP NIP. Trusted by more hackers.
Mean mean code
Today's Chuck Sawyer
Mean mean node
.
Though his stack is not for rent
Don't push dynamic environment
His compiler, a quiet defense
Riding out the stream of events —
The socket
Absolutely. It made my day. Thank you.