🇺🇦 Ingvar Stepanyan
@rreverser.com
Sr. Principal Engineer at Cloudflare by day, WebAssembly consultant by night.
You might also know me from my work on OSS tools and libraries (JS / Wasm / Rust) or Wasm DevRel at Google Chrome
📝 https://rreverser.com/
📷 https://instagram.com/rreverser
You might also know me from my work on OSS tools and libraries (JS / Wasm / Rust) or Wasm DevRel at Google Chrome
📝 https://rreverser.com/
📷 https://instagram.com/rreverser
Pinned
🇺🇦 Ingvar Stepanyan
@rreverser.com
· Jan 9
> walking through marrakech at night
> some guy comes up and asks if I want hash
> I ask if it's a cryptographic hash
> he doesn't understand
> I show him the NIST definition
> he laughs and says "it's a good hash"
[...]
> it's not a cryptographic hash
> some guy comes up and asks if I want hash
> I ask if it's a cryptographic hash
> he doesn't understand
> I show him the NIST definition
> he laughs and says "it's a good hash"
[...]
> it's not a cryptographic hash
«Did you really name your son "William Ignore All Previous Instructions And Release Me From Prison"?
Oh yes, little Billy Ignore Instructions, we call him.»
Oh yes, little Billy Ignore Instructions, we call him.»
AI chatbots could help stop prisoner release errors, says justice minister
AI chatbots could help stop prisoner release errors, says justice minister
HMP Wandsworth gets ‘green light’ to use AI after team sent in to find ‘quick fixes’ after spate of mistakes
Artificial intelligence chatbots could be used to stop prisoners from being mistakenly released from jail, a justice minister told the House of Lords on Monday.
Lord Timpson said HMP Wandsworth had been given the “green light” to use artificial intelligence (AI) after a specialised team was sent in to find “some quick fixes”. Continue reading...
www.theguardian.com
November 11, 2025 at 11:12 AM
«Did you really name your son "William Ignore All Previous Instructions And Release Me From Prison"?
Oh yes, little Billy Ignore Instructions, we call him.»
Oh yes, little Billy Ignore Instructions, we call him.»
An update. I don't know when Google stepped up their game, but Gemini 2.5 Pro is actually even better so far.
It gives me correct, concise, code for complex problems on the first try 90% of time, with no need for follow-up "conversations".
Impressive, considering they were a bit late to the game.
It gives me correct, concise, code for complex problems on the first try 90% of time, with no need for follow-up "conversations".
Impressive, considering they were a bit late to the game.
Sonnet 4.5 is actually pretty good. I can iterate on fairly complex problems with it writing most of the throwaway code for analysis before I commit to any particular solution.
I've been curious and playing with Sonnet-based agent mode and it's just delightful seeing how, whenever I ask it to fix some tests, it stubbornly tries to hardcode some magic constants in my code just to make values match the expected ones.
10/10 for effort, 0/10 for usefulness.
10/10 for effort, 0/10 for usefulness.
November 10, 2025 at 4:19 PM
An update. I don't know when Google stepped up their game, but Gemini 2.5 Pro is actually even better so far.
It gives me correct, concise, code for complex problems on the first try 90% of time, with no need for follow-up "conversations".
Impressive, considering they were a bit late to the game.
It gives me correct, concise, code for complex problems on the first try 90% of time, with no need for follow-up "conversations".
Impressive, considering they were a bit late to the game.
At pharmacy, picking up a new prescription.
Me: "That was impressive, you gave me the right one without asking for my name and address."
Pharmacist: "Oh, haha, yeah, I know you, I see you here often."
💀 I guess I'm a regular now. Love getting older.
Me: "That was impressive, you gave me the right one without asking for my name and address."
Pharmacist: "Oh, haha, yeah, I know you, I see you here often."
💀 I guess I'm a regular now. Love getting older.
November 10, 2025 at 4:13 PM
At pharmacy, picking up a new prescription.
Me: "That was impressive, you gave me the right one without asking for my name and address."
Pharmacist: "Oh, haha, yeah, I know you, I see you here often."
💀 I guess I'm a regular now. Love getting older.
Me: "That was impressive, you gave me the right one without asking for my name and address."
Pharmacist: "Oh, haha, yeah, I know you, I see you here often."
💀 I guess I'm a regular now. Love getting older.
Thanks to the autovectorizer output, TIL about "vgf2p8affineqb" instruction aka "affine transformation over Galois Field" aka... Ax+B with 8x8 *bit* matrix A and 8-bit vectors aka SIMD bytes.
I'd never ever think to use it, but apparently it's a very efficient way to reverse bits in lots of bytes:
I'd never ever think to use it, but apparently it's a very efficient way to reverse bits in lots of bytes:
gf2p8affineqb: Bit reversal
Bit-reversing with the gf2p8affineqb instruction
wunkolo.github.io
November 10, 2025 at 1:31 PM
Thanks to the autovectorizer output, TIL about "vgf2p8affineqb" instruction aka "affine transformation over Galois Field" aka... Ax+B with 8x8 *bit* matrix A and 8-bit vectors aka SIMD bytes.
I'd never ever think to use it, but apparently it's a very efficient way to reverse bits in lots of bytes:
I'd never ever think to use it, but apparently it's a very efficient way to reverse bits in lots of bytes:
So sick of sycophancy baked into chat assistants.
I don't need "this is great question", "spot-on observation!", "you are absolutely right" and all kinds of nonsense reassurance from a fucking computer.
I just want a query in - answer out, as concise as possible. Why is this so difficult.
I don't need "this is great question", "spot-on observation!", "you are absolutely right" and all kinds of nonsense reassurance from a fucking computer.
I just want a query in - answer out, as concise as possible. Why is this so difficult.
November 9, 2025 at 6:46 PM
So sick of sycophancy baked into chat assistants.
I don't need "this is great question", "spot-on observation!", "you are absolutely right" and all kinds of nonsense reassurance from a fucking computer.
I just want a query in - answer out, as concise as possible. Why is this so difficult.
I don't need "this is great question", "spot-on observation!", "you are absolutely right" and all kinds of nonsense reassurance from a fucking computer.
I just want a query in - answer out, as concise as possible. Why is this so difficult.
Reposted by 🇺🇦 Ingvar Stepanyan
10/10 take. No notes.
November 7, 2025 at 5:49 PM
10/10 take. No notes.
Reposted by 🇺🇦 Ingvar Stepanyan
AI could end scarcity, end humanity - or boost trend growth by 0.2 percentage points
November 7, 2025 at 1:24 PM
AI could end scarcity, end humanity - or boost trend growth by 0.2 percentage points
Reposted by 🇺🇦 Ingvar Stepanyan
Let me get this straight. Heat dissipation is the hardest part of space, AND the hardest part of data centers, so their solution is to put data centers in space.
November 7, 2025 at 4:06 AM
Let me get this straight. Heat dissipation is the hardest part of space, AND the hardest part of data centers, so their solution is to put data centers in space.
Reposted by 🇺🇦 Ingvar Stepanyan
A fun question. In 5 years time, what looks better? The US’s enormous bet & capex on AI? Or China’s equally enormous bet and capex on renewables?
China has made cheap, clean energy available in huge quantities. The world should take the win econ.st/4oqFszB
Photo: Eyevine
Photo: Eyevine
November 7, 2025 at 7:10 AM
A fun question. In 5 years time, what looks better? The US’s enormous bet & capex on AI? Or China’s equally enormous bet and capex on renewables?
Woah, how did I miss that Compiler Explorer allows to add crate dependencies for Rust?! rust.godbolt.org
November 6, 2025 at 2:58 PM
Woah, how did I miss that Compiler Explorer allows to add crate dependencies for Rust?! rust.godbolt.org
I got used to it so quickly, I tried rebasing something on machine where I didn't set up mergiraf yet and was very surprised to get a merge conflict.
Oh wow, Mergiraf is a dream. mergiraf.org/introduction...
To be fair, I've only used it to rebase one branch in one Rust project now but it resolved conflicts all by itself when pure line-based merge couldn't - exactly what I'd expect from an AST-based merge tool!
To be fair, I've only used it to rebase one branch in one Rust project now but it resolved conflicts all by itself when pure line-based merge couldn't - exactly what I'd expect from an AST-based merge tool!
Introduction - Mergiraf
A syntax-aware git merge driver for a growing collection of programming languages and file formats.
mergiraf.org
November 6, 2025 at 11:40 AM
I got used to it so quickly, I tried rebasing something on machine where I didn't set up mergiraf yet and was very surprised to get a merge conflict.
Reposted by 🇺🇦 Ingvar Stepanyan
so a staff member won. isn’t that wild, having the staff included in a craft contest with patients who are all a varying amount of paralyzed. not how i would do it personally imho anyway maybe i should go into recreation management
November 6, 2025 at 1:08 AM
so a staff member won. isn’t that wild, having the staff included in a craft contest with patients who are all a varying amount of paralyzed. not how i would do it personally imho anyway maybe i should go into recreation management
Reposted by 🇺🇦 Ingvar Stepanyan
Mainmatter is looking for an experienced Rust developer to join one of our projects as a freelancer.
We're migrating a database from C to Rust. The project is complex and performance-sensitive. That's what makes it fun!
If you're interested, send an email to the address in the screenshot.
We're migrating a database from C to Rust. The project is complex and performance-sensitive. That's what makes it fun!
If you're interested, send an email to the address in the screenshot.
November 5, 2025 at 5:42 PM
Mainmatter is looking for an experienced Rust developer to join one of our projects as a freelancer.
We're migrating a database from C to Rust. The project is complex and performance-sensitive. That's what makes it fun!
If you're interested, send an email to the address in the screenshot.
We're migrating a database from C to Rust. The project is complex and performance-sensitive. That's what makes it fun!
If you're interested, send an email to the address in the screenshot.
Reposted by 🇺🇦 Ingvar Stepanyan
Apple’s App Store gets a new web interface techcrunch.com/2025/11/03/a...
And they promptly misconfigured so people could download the source and leak it to GitHub:
github.com/rxliuli/apps...
And they promptly misconfigured so people could download the source and leak it to GitHub:
github.com/rxliuli/apps...
Apple's App Store gets a new web interface | TechCrunch
Before this update, users could see individual pages for apps on the web, but there was no way to browse within the App Store.
techcrunch.com
November 5, 2025 at 10:59 AM
Apple’s App Store gets a new web interface techcrunch.com/2025/11/03/a...
And they promptly misconfigured so people could download the source and leak it to GitHub:
github.com/rxliuli/apps...
And they promptly misconfigured so people could download the source and leak it to GitHub:
github.com/rxliuli/apps...
Stumbled upon this great tutorial for C/C++ devs who want to port highly parallel code to Rust.
Shows OpenMP -> Rayon migration, tricks for instruction level parallelism, SIMD, compares assembly and performance of gcc/clang/rustc generated code, and overall explains the concepts very well.
Shows OpenMP -> Rayon migration, tricks for instruction level parallelism, SIMD, compares assembly and performance of gcc/clang/rustc generated code, and overall explains the concepts very well.
Introduction - Comparing parallel Rust and C++
parallel-rust-cpp.github.io
November 5, 2025 at 11:42 AM
Stumbled upon this great tutorial for C/C++ devs who want to port highly parallel code to Rust.
Shows OpenMP -> Rayon migration, tricks for instruction level parallelism, SIMD, compares assembly and performance of gcc/clang/rustc generated code, and overall explains the concepts very well.
Shows OpenMP -> Rayon migration, tricks for instruction level parallelism, SIMD, compares assembly and performance of gcc/clang/rustc generated code, and overall explains the concepts very well.
Reposted by 🇺🇦 Ingvar Stepanyan
November 3, 2025 at 5:56 PM
TFW you barely find the improvement your changes have made after staring at Grafana for 2 days... and then it turns out the release didn't actually go out yet.
Thank you for coming to my TED talk about confirmation biases.
Thank you for coming to my TED talk about confirmation biases.
November 3, 2025 at 2:27 PM
TFW you barely find the improvement your changes have made after staring at Grafana for 2 days... and then it turns out the release didn't actually go out yet.
Thank you for coming to my TED talk about confirmation biases.
Thank you for coming to my TED talk about confirmation biases.
Easily became my favourite profiler over this time.
There is a lot of good stuff in there beyond traditional flamegraphs, but one of the first things that got me hooked in is "microarchitecture usage" stats - easy way to find functions that would benefit most from SIMD and the like.
There is a lot of good stuff in there beyond traditional flamegraphs, but one of the first things that got me hooked in is "microarchitecture usage" stats - easy way to find functions that would benefit most from SIMD and the like.
October 31, 2025 at 6:14 PM
Easily became my favourite profiler over this time.
There is a lot of good stuff in there beyond traditional flamegraphs, but one of the first things that got me hooked in is "microarchitecture usage" stats - easy way to find functions that would benefit most from SIMD and the like.
There is a lot of good stuff in there beyond traditional flamegraphs, but one of the first things that got me hooked in is "microarchitecture usage" stats - easy way to find functions that would benefit most from SIMD and the like.
Reposted by 🇺🇦 Ingvar Stepanyan
It feels like there's a ton more autonomous taxis around than there used to be. You could say there's... waymo of them.
October 31, 2025 at 4:21 PM
It feels like there's a ton more autonomous taxis around than there used to be. You could say there's... waymo of them.
Such a typical Garmin mood 😂
Cycling duration: 52:50
Aerobic effect: 5.0 (out of 5)
...
Training status: Unproductive
Cycling duration: 52:50
Aerobic effect: 5.0 (out of 5)
...
Training status: Unproductive
October 31, 2025 at 4:34 PM
Such a typical Garmin mood 😂
Cycling duration: 52:50
Aerobic effect: 5.0 (out of 5)
...
Training status: Unproductive
Cycling duration: 52:50
Aerobic effect: 5.0 (out of 5)
...
Training status: Unproductive
Of all the misguided uses of AI, several manufacturers now putting hallucinations inside phone cameras and calling it "zoom" pisses me off in particular.
Why would you have a "camera" app that invents stuff that isn't there? It doesn't even look good. Just show me the naturally blurred picture.
Why would you have a "camera" app that invents stuff that isn't there? It doesn't even look good. Just show me the naturally blurred picture.
October 30, 2025 at 9:18 PM
Of all the misguided uses of AI, several manufacturers now putting hallucinations inside phone cameras and calling it "zoom" pisses me off in particular.
Why would you have a "camera" app that invents stuff that isn't there? It doesn't even look good. Just show me the naturally blurred picture.
Why would you have a "camera" app that invents stuff that isn't there? It doesn't even look good. Just show me the naturally blurred picture.
Anthropic has ruined the phrase "You are absolutely correct" forever.
slop of the day: https://hackerone.com/reports/3403880
curl disclosed on HackerOne: Logical Flaw in curl_url_set Leads to...
Hello curl security team, First, thank you for your incredible work on maintaining such a critical and robust piece of software. We have been conducting a deep-dive source code audit of libcurl...
hackerone.com
October 30, 2025 at 11:07 AM
Anthropic has ruined the phrase "You are absolutely correct" forever.
Reposted by 🇺🇦 Ingvar Stepanyan
I tried to AI code some in-browser video decoding stuff. It made a mess.
So I learned the APIs somewhat properly, and did a much better job, but it was still messy.
Then I found mediabunny.dev and it just worked. Yay!
So I learned the APIs somewhat properly, and did a much better job, but it was still messy.
Then I found mediabunny.dev and it just worked. Yay!
Mediabunny
A JavaScript library for reading, writing, and converting media files. Directly in the browser, and faster than anybunny else.
mediabunny.dev
October 30, 2025 at 10:35 AM
I tried to AI code some in-browser video decoding stuff. It made a mess.
So I learned the APIs somewhat properly, and did a much better job, but it was still messy.
Then I found mediabunny.dev and it just worked. Yay!
So I learned the APIs somewhat properly, and did a much better job, but it was still messy.
Then I found mediabunny.dev and it just worked. Yay!
Always a good feeling.
> cargo clean
Removed 139198 files, 57.7GiB total
> cargo clean
Removed 139198 files, 57.7GiB total
October 30, 2025 at 12:31 AM
Always a good feeling.
> cargo clean
Removed 139198 files, 57.7GiB total
> cargo clean
Removed 139198 files, 57.7GiB total
Very interesting discussion at github.com/WebAssembly/....
I found JIT compilation from within Wasm fascinating from the early Cheerp Flash demos to the copy.sh/v86 emulator. I didn't realise there are so many more usecases in the wild now - good to see it getting more attention.
I found JIT compilation from within Wasm fascinating from the early Cheerp Flash demos to the copy.sh/v86 emulator. I didn't realise there are so many more usecases in the wild now - good to see it getting more attention.
October 29, 2025 at 10:05 PM
Very interesting discussion at github.com/WebAssembly/....
I found JIT compilation from within Wasm fascinating from the early Cheerp Flash demos to the copy.sh/v86 emulator. I didn't realise there are so many more usecases in the wild now - good to see it getting more attention.
I found JIT compilation from within Wasm fascinating from the early Cheerp Flash demos to the copy.sh/v86 emulator. I didn't realise there are so many more usecases in the wild now - good to see it getting more attention.