@_Felipe

@ApacheArrow / Databases / Compilers. (past @SDFLabs, VoDa, @Spotify). Rust/C++/TLA⁺🇧🇷 → 🇸🇪 → 🌎

felipe.rs
Joined June 2008
  • Tweets29.2K
  • Following2.5K
  • Followers5.5K
896Media
If you wanted fast but broken assembly, there’s a tool for that already! It’s the -O3 optimization level.
3
5
177
4,929
Let’s go Mario!
Mario Zechner
@badlogicgames
20h
see, i have come to a different conclusion. i have now entered my "gramps is annoyed at your thoughtless slop for clicks and will point it all out" phase.
3
674
Programming Languages aren’t fast nor slow. Programs implemented in them can be fast or slow. You can say some PLs impose overhead on certain constructs. Rewriting from Python to Rust makes it likely, but not certain, that performance will improve.
2
1
38
1,505
My SF trip is over! Returning to Brazil tomorrow morning.
4
18
858
Felipe O. Carvalho retweeted
Thomas Wuerthinger
@thomaswue
Sep 25
Replying to @filpizlo
Do you really think that writing a program in assembly makes it 17x faster than writing it in Rust? I wish compilers had that much potential 🤣
2
1
46
1,901
One day, tpot is talking about formal specs to make sure programs are correct. The other day the talk is about generating asm directly. Formal guarantees be damned.
3
20
710
dhh be like “look at how ugly Rust is!” then proceeds to show a beautiful snippet of polymorphic Rust code that can be compiled to code that doesn’t need virtual calls.
5
12
2
321
9,813
Impressive how a PR can have multiple pages describing the code with no mention of the motivation for the change because motivations don’t come into the LLM context.
1
30
686
When you realize type systems can be way better than Java’s type system in 2006 and you can remain consistent with your aesthetics by claiming you never actually look at Rust code because agents do all the work.
5
1
68
8,024
If you don’t try to break the TLA+ specs, you might not catch implementation mistakes. It’s very easy to assume atomicity where there isn’t one. At the same time, you can’t have a model with super fine-grained steps lest you end up with combinatorial blowup.
I ran it - and it passed cleanly (2941 states, no violation). That's a real (negative) finding, not a wasted run: this simplified model can't reproduce the bug, and it's worth understanding why before going further. Why it doesn't fail: in this flat model, WorkerClaimKey bundles "claim the key" and "send it" into one atomic step - a worker never sits in a state of "has claimed key i but hasn't sent it yet." DriverExitMainLoop (Main → DrainConnecting)

ALT I ran it - and it passed cleanly (2941 states, no violation). That's a real (negative) finding, not a wasted run: this simplified model can't reproduce the bug, and it's worth understanding why before going further. Why it doesn't fail: in this flat model, WorkerClaimKey bundles "claim the key" and "send it" into one atomic step - a worker never sits in a state of "has claimed key i but hasn't sent it yet." DriverExitMainLoop (Main → DrainConnecting)

1
23
2,423
You have to read the formal spec to not have to read the code.
2
1
33
1,052
This is good news because reading the specs is much easier than writing them or the refined implementation.
6
143
Felipe O. Carvalho retweeted
Preston Thorpe
@PThorpe92
Sep 23
With @georgecurtiss and @_Felipe at @WeAreDevs
4
2
67
2,133
TLA+ mentioned!
Boris Cherny
@bcherny
Sep 22
I used Opus 5.5 to formally verify the Claude Agent SDK using Lean. A couple short prompts = 16 PRs fixing various bugs and race conditions. Video attached. TLA+ also works well. I sometimes combine Lean and TLA+ to look for issues around data flow, concurrency, and state mgmt. I don't know either language well, but Claude is excellent at both. This approach is super useful for formally modeling your code and finding bugs that a human probably wouldn't have spotted. Is formal verification the future of coding (or at least, bug finding)?
1
30
4,044
My face doesn’t hide that I’m a bit star-struck. I have been watching @andy_pavlo’s lectures for so many years! 🤩
Andy Pavlo and me

ALT Andy Pavlo and me

2
109
2,480
I’m at the Rows & Columns @ClickHouseDB event. @andy_pavlo is teaching us about the history OLAP/OLTP/HTAP and how it relates to Larry Ellison’s marriages across the decades.
Broken Dreams. Broken Promises. Broken Marriages. 60 years of mixing transactions and analytics.

ALT Broken Dreams. Broken Promises. Broken Marriages. 60 years of mixing transactions and analytics.

2
2
69
1,789
The hard thing about monetizing the automation of shopping is that most people love shopping. They are addicted to the process. They are not going to delegate their hobby to AI.
3
13
703
“One must imagine Dijkstra happy.” — Albert Camus
1
1
25
902
I learned this a long time ago, but the most important lesson was shutting up about it. It does help when naming stuff in a compiler project though.
Dmitrii Kovanikov
@ChShersh
Sep 22
After programming for 16 years, I finally learned the difference between “function arguments” and “function parameters”. I’ve been using them interchangeably assuming they’re synonyms.
3
1
58
5,263
Installed MacTeX. It’s ~7GB download these days 😬
4
8
1,175
Load more