[ mona / prog / sol ]



Have you read your SICM today? [study group]

1 2020-06-14 21:33

To quote http://textboard.org/prog/77

SICP - Stream Entry
SICM - Once-Returning
Functional Differential Geometry - Non-Returning
Software Design for Flexibility - Arhantship

What are your plans for this summer? Anyone wants to read SICM?

Let's make it self-paced, beginner-friendly and not a dick swinging contest. Who's in?

2 2020-06-15 06:41

I want to, but I will need some maths and physics first. Last time I attempted reading SICM, I couldn't even do the very first exercise.

3 2020-06-15 07:11

This, it takes pages of Lagrange'ian equations until the first Scheme is presented, and without a formal education in physics, I don't know how to get that. Even Wikipedia says (https://en.wikipedia.org/wiki/Structure_and_Interpretation_of_Classical_Mechanics):

The book is used at the Massachusetts Institute of Technology to teach a class in advanced classical mechanics, starting with Lagrange's equations and proceeding through canonical perturbation theory.

I'll be waiting for Software Design for Flexibility.

4 2020-06-16 04:27

Normally I would love to, but to my everlasting shame I'm still working through SICP. Shhhh.

"Advanced" here is a bit vague. Best to check out the actual course website:

This subject awards G-LEVEL Graduate Credit, however the subject is appropriate for undergraduates who have taken the prerequisites. Undergraduates are welcome.
Prerequisites: 8.01, 18.03, programming experience

8.01 is introductory classical mechanics, i.e. the Newtonian mechanics that everyone has to take, and 18.03 is differential equations. I don't know how it is in the CS world, but in my real engineering major it was a basic requirement. So it is a graduate course, but with some relatively fundamental prerequisites. That said, I just took a look at the first few pages and I agree that it's dense. In that respect it looks like the second edition is a bit more gentle than the first edition that OP linked to:

I can't vouch for it personally, but for an introduction to the subject it might be worth checking out The Variational Principles of Mechanics by Cornelius Lanczos, which Sussman recommends at http://aurellem.org/thoughts/html/sussman-reading-list.html and which seems to be highly regarded.

5 2020-06-16 07:55 *

There's really no hurry, threads are not pruned and we can start with introductory material.
8.01 is available with lectures videos at MIT OCW
and EDX (archived, you must log in)

For a calculus refresher:

And then 18.03

No deadline.

6 2020-10-23 04:16

Found this comment from a few months ago on The Website That Must Not Be Named. I'm not sure whether to call it bizarre or admirable:

I am working on something like this myself. I started by reading the Structure and Interpretation of Classical Mechanics, which uses Scheme to teach Hamiltonian and Lagrangian mechanics. And it's much more effective than an ordinary math/physics book. Normal math is a kind of code, except that the VM that executes it is your brain. You (or I, anyway) can only progress if you understand absolutely everything down to the last detail. Programming is much easier. If you don't understand something you can put together a little simulation to poke at the edge cases.
So I finished SICM and I thought, "wouldn't it be cool if I could keep learning physics like this?" And so now I've gotten in touch with some physics postdocs (who are paid shockingly little). I pay them to learn Scheme and encode quantum mechanics, general relativity, statistical mechanics as scheme programs. I work on this about 10 hours a week. In a year or two I'll have knowledge equivalent to an ABD physics grad student, plus information that can take other people from modest beginnings to the same level.
One thing this project has taught me is that students have shockingly little power in their relationships with teachers. I am a major source of income for my postdocs. Some of them may be prioritizing me over some of their other duties. And it really shows. I'm a good self-learner, but there is no substitute for having someone work really hard to anticipate all your questions.



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1 2020-10-16 07:50

hi all,

PicoLisp power user here, AMA.


10 2020-10-21 22:45 *

Here's a fun exercise. All LISPs named after divisional metric prefixes.

decilisp - Does not exist
centilisp - Does not exist
millilisp - Abandoned
microlisp - AVR/ARM only. No hardware access. http://www.ulisp.com
nanolisp - Abandoned
picolisp - https://picolisp.com
femtolisp - Abandoned
attolisp - Abandoned
zepto - Abandoned
yocto - Abandoned

11 2020-10-21 22:56 *

No lisp is ever abandoned in my heart.

12 2020-10-22 18:32

>>10 also, Kilo Lisp https://www.t3x.org/klisp/index.html

13 2020-10-23 00:39

Same guy just wrote lisp from nothing.

14 2020-10-23 10:18 *

Only God can create something out of nothing.



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Infinite compression

1 2020-10-22 04:09

The general idea of Infinite Compression is extremely simple:
1.All files are converted to integers, integer X in this case.
2.Arbitrary precision floating point numbers A and B that are
X and X+1 respectively(interval X.0 <->(x+1).0) are generated.
3.The numbers A&B(and effectively the interval between them) is multiplied by 2^n(n can be adjusted later to search more space).
4.The resulting (x*2^n)<->((x+1)*2^n) interval is set as target area for specific formulas.(e.g. a very short polynomial).
5.The variables of polynomial formula are tried to match a result inside the interval in #4, if its not found the number 'n' is changed and process repeats as in #3.
6.When the search find a set of variables which result in the some number that is within interval the variables,n(in 2^n) and file size are recorded into a 'hash-like' link.
7.If the search fails for all reasonable n' values the file is appended with "dummy values"(since real size is recorded) and search is run again on the 'file+dummyarea'.

There is also a way to pre-emptively search 'file+dummydata' as in interval arithmethic(think dummydata with any multiplier), discarding the 'dummydata' later:
any effective multiplier can be used instead of 2^n, granted its easily generated by formula.
Name: Email:

2 2020-10-22 04:16 *

Name: Email:

3 2020-10-22 04:21

It was copied from tinychan.

4 2020-10-22 04:21


5 2020-10-22 06:52

There are also ways to make files less entropic(Gray code):
applying repeatedly x^(x>>1) on the file integer representation, will produce a form with has least 1's vs 0's.
This form can be back-transformed to x, by recovering the pre-xor bits of each step(as it represents change of old bit to next bit).



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Everything Emacsen

1 2020-04-18 11:53

Let's talk about Emacsen: GNU Emacs, Guile Emacs, edwim, mg, etc. Do you use them? Do you like them? Do you extend them? Any tips to share? Any questions to ask?


27 2020-10-15 21:18

Is anyone aware of attempts to implement CL's reader macros (or a subset thereof) in elisp?

28 2020-10-19 16:12

There's this: https://emacssurvey.org/

It's open until 30.11.2020, consider participating, so that the VSCode and Vim users don't overshadow everything.

29 2020-10-20 13:01

Does anyone here use GCC-Emacs? I heard it was actually quite usable with no real issues, and it seems that it will be added to my distribution within the month.

30 2020-10-21 09:51

I tried it a week ago, and it's basically as stable as master, but probably not more stable.

31 2020-10-21 16:36

That's honestly not too bad, but it does temper my enthusiasm slightly. At least baring any obvious bugs in the beginning I'll try to keep it in the back of my head that any errors I'm debugging (inevitable bugs in personal functions and configuration) could be due to working on top of an unstable branch. Thanks for sharing.



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Fixed point math tutorial for PicoLisp

1 2020-10-18 18:35


2 2020-10-18 19:38

This is a very nice feature.



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Doffing his fez with an impish grin, The Sussman returns.

1 2020-02-06 03:53

You heard it here first, folks. The Sussman's next book, Software Design for Flexibility, will be out soon. Abelson talked about it at around 25:45 in this interview from last year: https://corecursive.com/039-hal-abelson-sicp/, and it's named in the documents linked at the page for the "Advanced Symbolic Systems" course that Sussman is currently teaching: https://groups.csail.mit.edu/mac/users/gjs/6.945/

It's a graduate level class, meaning the book will likely be a step up from SICP. To whet your appetites while you wait, you can find talks Sussman has given over the past several years on Youtube, where he talks about a lot of the same principles regarding flexibility.

Now that The Sussman has four mind-bending books out, we might consider replacing satori with the Theraveda Four Stages of Nirvana:

SICP - Stream Entry
SICM - Once-Returning
Functional Differential Geometry - Non-Returning
Software Design for Flexibility - Arhantship


31 2020-10-20 21:56 *

I came across Theravada separately from Scheme, having been interested in Buddhism for a long time and finding its plainspokenness appealing and more in line with the suttas compared to Mahayana, particularly the ten-thousand-Buddhas-dancing-on-the-head-of-a-pin quality of Pure Land. So Sussman putting out a new book seemed a good opportunity to riff off of the /prog/ joke about satori, as >>28 says. It's true that I'm certainly no sotāpanna, and thanks to a fraught living situation haven't even been able to maintain a regular meditation schedule lately. I'm curious about the other instance in which you saw Theravada mentioned with reference to Scheme, if you want to share.

Hardly. The predominant form of Buddhism known to the West is Zen, starting from the Beats on to the hippies, after which it was commercialized and New Aged into the vapid modern pseudo-Buddhism that has led to such absurd misconceptions as "Buddhism is nihilistic" and "meditation is thinking about nothing". There's also some minor awareness of Tibetan Buddhism purely because of the Dalai Lama (a shame because tantric imaginal practices are fascinating) but almost zero knowledge of Theravada, which I think is a little too rigid to be as easily commoditized beyond a few relatively small internet communities where people like to LARP about the sizes of their dharmic penises.

32 2020-10-20 22:43 *

Didn't Buddhist modernism start in the Theravada tradition, in Burma? There is also the whole insight movement thing right?

33 2020-10-21 04:48 *

You're right, of course. To be honest the whole insight thing slipped my mind because despite having its roots in Theravada it feels like any mainstream recognition it had has been very quickly co-opted into the generic mindfulness industry. It also seems to be have been driven heavily by the Goenka centers and I hesitate to describe them as Theravada because they've branded themselves just around "vipassana" and strike me as kind of cultish. But I suppose that does prove that Theravada can be commoditized just like anything else, though I still believe it is less memetic than Zen.

That's not to say there aren't plenty of serious practitioners that have come to Theravada in recent years, but I don't think that it has any real recognition, under its own name, among "hippies" or adherents of "California Ideology" (whatever the fuck that means), let alone the average person. But then again I'm not an expert, a hippie, nor a Californian and certainly no arbiter of who gets to call themselves what, especially since I myself am not devoted enough to identify as a Buddhist.

34 2020-10-21 12:56 *

Memes don't die learn the hard way, the really really hard way. I think using theravada here is more quality but my post was about satori and definitely not revisionism since I'm bored.

35 2020-10-21 13:05 *

Yah, that makes sense to me, I heard that there were lots of authentic Theravada all over the place due to immigrant communities, I imagine there are many authentic converts as you mention. In case you're curious The California Ideology is pretty much what exists today where there were once hippies: https://www.metamute.org/editorial/articles/californian-ideology (tldr: https://en.wikipedia.org/wiki/The_Californian_Ideology (LessWrong is an excellent example of this on the internet))



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Challenge^2: Floating Point without Errors

1 2020-10-16 10:11

Implement this RC challenge, without loading external libraries/programs in your favorite language(standard library parts are allowed).

1. All three tasks must be solved exactly - no errors.
2. No loading any external programs or libraries.
3. Solution should be as laconic as possible: you are allowed to implement anything but larger solutions will be treated as weaker than shorter ones.


54 2020-10-18 16:27

Also it gives impression that its based on pedagogical problems with
"current definition of a limit" and hints of relation to intuitionism
while Robinson proved non-standard analysis with rigor.
the narrative and selective quotes, give
the overall impression of flimsy,irrational system that can't compete with
standard analysis - something more suited to academic studies on 'social impact of math' and various philosophical works.

55 2020-10-18 16:44

I have not be as emotionally invested in "infinitesimals" "limit definition" and "Archimedean property" if these were not based on "Science is Settled" arguments that don't have logical basis.
(note: i don't deny that some areas of math are highly controversial like
ultrafinitism, which many view as Flat Earth is viewed by geologists)
The current mathematics structure is like a house of cards relying on
axioms that aren't acknowledged as axioms or proved by circular logic where proofs are relying on systems constructed using these axioms.
When a contradiction in a system is spotted, the usual reply that "its wrong due X"
ignores that X itself is a products of current system and alternatives to X don't exist or aren't developed(due lack of interest or paradigm dominance).

56 2020-10-18 16:57 *

I tried to watch a lecture on non-standard analysis, but they basically built this new large field R(x) composed of rational functions such that R ⊃ R(x). Such that R(x) does not satisfy the Archimedian Property, and is not Dedikind-Complete, but then threw it out because it wasn't sufficient for some reason. I'm a bit tired now, but I might watch the second part of the lecture series where they actually define R*. I couldn't find any definitions online which I could understand with my current mathematical abilities.

57 2020-10-18 17:14 *

I meant R ⊂ R(x), sorry.

58 2020-10-20 09:54 *

For those who might wonder where the error >>28 is but do not wish to engage, the step from "1*(1/10)*(1/10)*(1/10)*...=0" to "1=0/(1/10)/(1/10)/(1/10)/..." repeats the same fallacy >>27 because "1*(1/10)*(1/10)*(1/10)*..." is lim[n->inf](1/10)^n and there is no real number that you can multiply it with to ever get 1 back.

As for the archimedean trolling, you can dismiss it entirely. The proof is quite simple. If a field is ordered and is non-archimedean then it is incomplete, but R is both ordered and complete, thus R is archimedean. The other proof that was posted >>31 >>33 is also valid.



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Reader Macros - the Unique and Beautiful LISP feature

1 2020-10-14 18:10

What happens when you type a wrong 'LISP-based JSON' block inside LISP?
When reader macros reach this "inline JSON file segment", what kind of errors start appearing?
My guesses
1.They resort to some overarching ParseJson()??? function generating exception
2.They generate some local "reader macro" error


40 2020-10-18 09:11


C is a complete language, compiler, operating system, documentation system, development system, etc.

Are you out of your mind? There's no C operating system. What the fuck are you even talking about?

41 2020-10-18 09:33

A C Operating system includes a C Processing Unit(secretly a stolen LISP machine surplus part modified to interpret C opcodes) with a basket of live lambdas connected to give lifeforce to unholy void pointer table where functions are created and destroyed in a cycle of Garbage Collection(hidden by epithets such as Cache Eviction). The machine weights 30 tons and is requiring 200 Amp current cables to operate. Only authorized Intel mainframe programmers who have advanced to the rank of Cee Grandmaster can be eligible for about 3 hours of computing time per week. Distribution of C operating system is subject to USA DoD export restrictions, as it appear to be a powerful artifact able of containing Spirits of Computation(not included with the purchase).

42 2020-10-18 12:29 *

I'm saving this, the somewhat real C Processing Unit is called hobbit, only ever used in BeBox prototypes and theoretical hobbit based Apple newton. The widely accepted C standard describes some parts of an operating system and a development system, I'm not sure if that's what >>35 meant to push compared to a dialectic that has everything. The closest thing to a C operating system running on a C machine is Plan9 first edition using a hobbit BeBox prototype or Plan9 beta using a CRISP evaluation backplane from AT™T, if that even existed with support.

a powerful artifact able of containing Spirits

This is sometimes described as goetia but that extents to what everyone is using right now, not a specific artifact.

43 2020-10-18 15:14 *


I doubt C would be excellent on many non-von Neumann architectures

C dominates Harvard as well as von Neumann.

44 2020-10-22 19:34 *

>C dominates Harvard as well as von Neumann.

Most code written today is actually not C.



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what will stop me to spam on this textboard?

1 2020-05-28 15:43

what will stop me to spam on this textboard?


3 2020-05-28 16:14 *

My mom.

4 2020-05-28 20:28 *

Some Parts Are Mods

5 2020-10-14 18:44

If only that worked...

6 2020-10-16 04:55

The code of conduct

7 2020-10-16 07:35

Better idea: add something in the spirit of "We support the right of mentally ill to surgical self-mutilation" to every page, those deplorable spammers will surely leave and will never debate you.



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Muh Type Safety

1 2020-10-16 03:19

Imagine advertising complete type safety, dependent types and complete typechecking and ending up with this.

2 2020-10-16 03:31 *

This would never happen in Anaconda Scheme.

3 2020-10-16 04:07

Idris2 is bootstrapped in Scheme:
https://raw.githubusercontent.com/idris-lang/Idris2/master/bootstrap/idris2_app/idris2.ss <-- entire Idris program



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New Thread

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