@ApacheArrow / Databases / Compilers. (past @SDFLabs, VoDa, @Spotify). Rust/C /TLA⁺🇧🇷 → 🇸🇪 → 🌎 bento.me/felipe
Joined June 2008
- Tweets 28,216
- Following 2,427
- Followers 5,124
- Likes 36,756
844 Photos and videos
ALT I WISH THERE WAS A WAY TO KNOW YOU’RE IN THE GOOD OLD DAYS BEFORE YOU LEAVE THEM
17h
imagine if we went back to pushing tab full time
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Time to stop polishing the hot-reload implementation of a Rust egui app and start actually implementing the app.
Watch script rebuilds shared library on source saves and trigger rebuilds. App is watching .dylib file and errors file.
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Jun 12
Among the many advantages of Rust not supporting inheritance (you're forced to compose and delegate), a big one is not having to deal with the awkwardness of virtual destructors.
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Jun 12
This point is even stronger if you don't understand this tweet because you have no idea about the pitfalls of virtual destructors in C .
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Jun 12
Amethyst: Adaptive Compaction for LSM Trees via Segment-Level Policy Selection
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Jun 11
I have one tmux session per worktree (from 2 to 5 depending on project) containing at least 3 shells each: nvim, git, claude (or codex) CLI.
The tmux session switcher shows the currently checked-branch on the worktree.
Starting these sessions is automated with smug. It works!
The people that act like git worktrees aren’t confusing are the same people that act like they can taste the difference b/w a $10 and $100 bottle of wine
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Jun 10
Spent the weekly token limit on my personal Codex subscription to port LevelDB from C to unsafe Rust (Bun-style). Basic fillseq benchmark shows it achieves only half of the throughput of the original.
ALT C original fillseq : 2.324 micros/op; 47.6 MB/s Rust port fillseq : 4.302 micros/op; 25.7 MB/s
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Separate tmux tab running Codex that is only about hacking on Pyhton scripts that generate HTML pages with all kinds of useful commit/codebase visualization aids.
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Learning programming from scratch in 2026 requires a superhuman level of intellectual honesty and work ethic. Metacognition bankruptcy. You don't know what you know and what you don't know anymore as a student.
ALT Yeah, I think people are going to need a lot of motivation to learn programming from scratch when you can get any basic program written by Al.
Jun 5
What is happening to universities is troubling.
Students just have AI do their programming assignments. They seem to no longer do any work. It is just pure AI.
I am not joking. Students complete an entire course, and then end up not being unable to write a 3-line function.
So we fail them.
Again and again.
Some fight me : « Look at the code I can do !!! »
« Yeah, but when asked to code without AI, you can't do anything. »
Whiteboard interviews are going to be either retired or it is going to be a bloodshed.
How can you pass someone in a programming course when they can't write a single function without AI?
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Coding agents makes software engineering work even harder to objectively measure. It's harder than ever to hire a team of developers, deploy some easy-to-manage automatable process and get quality output. Engineering good will is required more than ever.
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Interesting C /Rust std lib difference to be aware of:
C : std::vector::reserve(total_capacity)
Rust: std::Vec::reserve(additional_capacity)
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OS kernel vs compute kernels
I wonder how much confusion has resulted over the years from "kernel" meaning "code that runs with the S bit set"(1) to one set of engineers, and "numerically intensive applied math code"(2) to another.
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$MSFT finally adding UNIX commands to Windows because of AI agents is an interesting turn of events. Microsoft could have made Windows more usable BEFORE but they had to wait until computers trained to use computers couldn’t use Windows.
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Felipe O. Carvalho retweeted
Jun 3
"It is a myth that a DBMS operates on data on disk". (A mentor told me this years ago, but I'm sure there are many Stonebraker/Gray/Pavlo quotes to the same effect.)
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"Baudrillard claims that current society has replaced all reality and meaning with symbols and signs, and that human experience is a simulation of reality."
VICTORIA SCRET SHARES ARE UP 50% TODAY
AFTER THE COMPANY CHANGED IT’S STOCK SYMBOL TO VERY SEXY $VSXY FROM $VSCO BEFORE
THE COMPANY ALSO REPORTED EARNINGS EARLIER TODAY
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The solution to employees using too many tokens will be similar to what most companies do regarding food. They don't like giving you food for free even though you need to eat to keep working. The employees will have to pay for the tokens from their salary stipend.
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The stipend will be the baseline you're expected to spend, but for more tokens you will have to take from your salary.
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You put a database on S3, so now every transaction commit is as durable as S3 guarantees it to be? Not necessarily.
You put a database on a server, now it allows clients to use in parallel? Not necessarily.
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I love this. Rust also has it as std::hint::unreachable_unchecked. If you have another way to prove the branch in indeed unreachable, it allows the compiler to optimize the chain of branches that lead to it.
Jun 2
C devs love Undefined Behaviour so much,
They even made a function to introduce UB on purpose.
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It's a way to telling the compiler about pre-conditions in reverse. The direct way being std::hint::assert_unchecked.
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Rust keeps the checks in debug builds. So every time you run the debug build, you are testing against UB ever being exercised.
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