🇺🇦 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
Reposted by 🇺🇦 Ingvar Stepanyan
This blog post from the Android team is a great counterargument to the common trope "but shipping in Rust is much slower". security.googleblog.com/2025/11/rust...
November 13, 2025 at 10:56 PM
This blog post from the Android team is a great counterargument to the common trope "but shipping in Rust is much slower". security.googleblog.com/2025/11/rust...
Lol what is Visual Studio doing?
November 12, 2025 at 11:23 PM
Lol what is Visual Studio doing?
Haven't tried myself yet, but this VSCode extension for customisable debug visualisations looks absolutely amazing. marketplace.visualstudio.com/items?itemNa...
November 12, 2025 at 5:00 PM
Haven't tried myself yet, but this VSCode extension for customisable debug visualisations looks absolutely amazing. marketplace.visualstudio.com/items?itemNa...
That's actually an interesting idea.
Would be expensive as hell, and I bet Microsoft/Github thought of and played with it too,but what if each repo's history would be used as a training input to produce per-repo instructions automatically behind the scenes?
Would be expensive as hell, and I bet Microsoft/Github thought of and played with it too,but what if each repo's history would be used as a training input to produce per-repo instructions automatically behind the scenes?
Why add AGENTS.md when we already have CONTRIBUTING.md?
Why does it need so much context in prompts when the entire project history is in git/GitHub?
Why does it need so much context in prompts when the entire project history is in git/GitHub?
November 12, 2025 at 2:11 PM
That's actually an interesting idea.
Would be expensive as hell, and I bet Microsoft/Github thought of and played with it too,but what if each repo's history would be used as a training input to produce per-repo instructions automatically behind the scenes?
Would be expensive as hell, and I bet Microsoft/Github thought of and played with it too,but what if each repo's history would be used as a training input to produce per-repo instructions automatically behind the scenes?
Reposted by 🇺🇦 Ingvar Stepanyan
Here's VSCode with GitHub Copilot side-by-side with Claude Code, on the same git repository, with the same question that requires deep analysis of a large code base to produce a decent answer.
GitHub Copilot: 1 minute, excellent answer
Claude Code: 2 minutes later, still waiting
GitHub Copilot: 1 minute, excellent answer
Claude Code: 2 minutes later, still waiting
November 11, 2025 at 9:09 PM
Here's VSCode with GitHub Copilot side-by-side with Claude Code, on the same git repository, with the same question that requires deep analysis of a large code base to produce a decent answer.
GitHub Copilot: 1 minute, excellent answer
Claude Code: 2 minutes later, still waiting
GitHub Copilot: 1 minute, excellent answer
Claude Code: 2 minutes later, still waiting
Reposted by 🇺🇦 Ingvar Stepanyan
New post: "Async and finaliser deadlocks", based on an accidental poke from a recent episode of the excellent @oxide.computer podcast tratt.net/laurie/blog/...
November 12, 2025 at 11:28 AM
New post: "Async and finaliser deadlocks", based on an accidental poke from a recent episode of the excellent @oxide.computer podcast tratt.net/laurie/blog/...
@robertknight2.bsky.social oh no, I overflowed your repo
November 12, 2025 at 3:31 AM
@robertknight2.bsky.social oh no, I overflowed your repo
«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.