tromp 12 days ago

Interesting how the obfuscated code is explained by slowly unobfuscating it step by step. This is the reverse of how obfuscated code is normally created: by starting with understandable code, and then slowly obfuscating it bit by bit (as I explained for this IOCCC submission [1]).

I say normally because one could also have a superoptimizer search for a minimal program that achieves some desired behaviour, and then one has to understand it by slowly unraveling the generated code.

[1] https://tromp.github.io/maze.html

trescenzi 12 days ago

I’ve used reverse Polish notation as an interview question many times. It works well because if someone’s never seen it you can learn a lot about their basic understanding of algorithms. But if they are aware of how easy it is you can extend it forever by adding symbols, improving the algo they build, or doing something like this.

  • eleumik 12 days ago

    You are a crazy sadic bastard

    • AdieuToLogic 11 days ago

      Such is the result of delving into languages such as Forth[0].

      Can you make programs with it smaller than assembly language? Sure.

      Will you come out the other side a mad hatter speaking of things such as words, dictionaries, and washing machine firmware? Well, I can only speak for myself...

      :-D

      0 - https://forth-standard.org/

martijnarts 12 days ago

> if you take the time to understand what this code does, you’ll learn a surprising amount about WebAssembly!

It's a shame the article mostly teaches about codegolf tricks, and the actual wasm info is left to a single commented code block.

Nonetheless an interesting article about JavaScript quirks though!

  • hinkley 12 days ago

    “Fits in a tweet” can be safely assumed to mean lots and lots of code golf.

Lerc 12 days ago

Really interesting. I considered having a go at a RPN to WASM converter when I was making https://c50.fingswotidun.com/

I ended up converting the RPN style notation into a JavaScript string and creating a new function, which lets the JIT sort it out.

https://c50.fingswotidun.com/show/?code=xy!2*!2y!*6%2Bo2%2Fv...

which has the code

    xy!2*!2y!*6+o2/vy#!*:Cy#*+z#d!;*:ze!xy*4s*43/*e+*+
becomes

    ((round(z) * ((v * (1 - round(y))) + (clamp((( ((x*(2**((2 * (1 - y)) + 6))) ^ ((1 - ((1 - y) * 2))*(2**((2 * (1 - y)) + 6)))) /(2**((2 * (1 - y)) + 6))) / 2)) * round(y)))) + ((1 - round(z)) * ((1 - smoothStep(z)) + smoothStep((((x * y) * sin(4)) * (4 / 3))))))

It would be interesting to see the performance difference from a wasm version, but in the end I found the human(ish) readable expression to be quite useful too.

Originally I created an interpreter for a code as a texture maker for code golfed javascripted games. https://github.com/Lerc/stackie

There's potential for a WASM implementation to be both smaller than the small version and Faster than the fast version.

marianoguerra 12 days ago

post co-author here, let me know if you have any questions :)

deivid 11 days ago

WASM is cool; I've started implemented a CPU that runs unmodified WASM in Verilog, but I'm finding the feature creep on the instruction set (SIMD, GC) to take away from the initial values behind WASM (simple, small)

  • sitkack 11 days ago

    You can ignore SIMD and GC (for now). SIMD explodes the complexity level of Wasm, esp when there is WebGPU. I am curious how you are handling layout and how you are handling all the irregular sizes.

  • enos_feedler 11 days ago

    I don't think WASM's value was ever in a hardware instantiation of the actual instruction set.

    • deivid 11 days ago

      Oh, I don't think so either, but if you think back to the asm.js times, there was a clear goal of "simple and higher perf", but now it's going in a direction for maximum compatibility with existing stacks (GC, WASI, etc) at "any" cost

kragen 12 days ago

This is really impressive. It is over 140 characters, but I guess "a tweet" can be any length now.

  • pdubroy 12 days ago

    Co-author of the post here — we had 280 characters in mind. :-)

  • lcnPylGDnU4H9OF 12 days ago

    I have never used Twitter so I might be mistaken but I believe the limit has been 280 for a while now, which is why the first one at 269 bytes would also have fit.

    • GrumpyNl 12 days ago

      Twitter was based on sms, the standard SMS character limit is 160. They used 140 so they could use the remained 20 chars for other purposes.

      • acuozzo 12 days ago

        140 and 160 are related when it comes to SMS.

        The GSM-7 alphabet is the most common one in use with SMS (or, at least, it was as UCS-2 is more common now with emojis and such).

        160 is the number of GSM-7 characters.

        160*7/8 = 140 which is the number of bytes in the userdata portion of the TPDU.

        • pests 12 days ago

          I don't think the Twitter choice of 140 was anything to do with this though and is just a coincidence. Back during dumbphones the only way to receive tweets while mobile was via the texting interface, and it would want to prepend the username. I don't think reserving 20 for the username has anything to do with how many bits are used to represent the alphabet.

        • kragen 12 days ago

          That's coincidence, though. I used Twitter to keep in touch with friends via SMS in 02008, and the messages had space for a prelude to say who they were from. In the opposite direction, you could use that space to tell Twitter to send the message privately to someone.

      • benatkin 12 days ago

        The username length restriction might come partly from that. They could surely relax it by now, though. I saw it at play this week when @SecondGentleman (15 characters) changed to @SecondGent46.

    • jsheard 12 days ago

      Yeah it was changed to 280 for all users in 2017. That's still the default limit, but paying users can exceed it now.

parlortricks 12 days ago

Is this a Tweet or a Xit (zit)? ha.

This is cool though, i love these programs that exist in these constraints, like Dwitter does with the demoscene.

actionfromafar 12 days ago

[flagged]

  • userbinator 12 days ago

    I prefer calling it an x-cretion.

    • exe34 12 days ago

      Xitter, with the X pronounced as a soft Sh