
UX Engineer @Microsoft | creator of those easing functions | building next-gen Responsive Easing tools
Brooklyn, NY
Joined October 2008
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I'm building a motion curve editor beyond your wildest fantasies.
I've been head down solving new easing equations for the last 13 months.
I promise nothing less than a quantum leap in easing technology.
Robert Penner retweeted
I wanted to share something I built over the last few weeks: isometric.nyc is a massive isometric pixel art map of NYC, built with nano banana and coding agents.
I didn't write a single line of code.
For overstretch, you can ask your agent for soft clamping with elastic saturation.
Design Engineering Tip:
Try giving elastic drags a limit.
Most rubber-band effects are linear, so the further you pull, the further it stretches. iOS uses a curve instead: it resists more the further you go and never passes a maximum.
const rubberBand = (x, d, c = 0.55) =>
(1 - 1 / ((x * c) / d + 1)) * d
Robert Penner retweeted
I've read this 3 times and feel like I'm losing my mind.
Tao is comparing an AI math proof to an AI cancer cure, which is insane enough by itself.
But the point of the comparison is that just like you would obviously rather die from cancer than accept an AI cure a human doesn't understand, we should reject AI proofs that mathematicians don't understand.
The mathematicians have truly lost their minds.
Robert Penner retweeted
Terry Tao: "Problem-solving alone is now actively harmful to mathematics."
I would like to politely disagree, and encourage everyone to continue solving math problems.
teorth.github.io/tao-web/sli…
Robert Penner retweeted
Most of the recent math results were not reached by a swarm, the way Navier–Stokes was. I think that part got lost in the excitement around the release. OpenAI's unnamed internal model, which I'm going to call Aeon, reached most of them in one shot, from a single prompt, with no interruptions. This model did not even exist before the end of August, and it is still training. Notice how the returns are not dropping off? That chart is from a month ago. It is a log scale. What does Aeon look like now?
On average, each result used three hours of thinking. Aeon was given 4000 problems to work on by OpenAI. How many more have been solved in the last three days? That number is not zero.
It's like hearing notes in a song that is slowly rising. I don't think Pacing the Frontier was just about Hugging Face or hacking. They've seen how close we are to closing the loop, and as the hour draws near, their resolve begins to quaver. The last piece was model creativity, and I think that threshold was crossed internally by Anthropic and OpenAI in September. You see it in Opus 5.5, which gets it from Fable 5.5. You see it in the math results from Aeon.
All that was needed to start the event was the ability for models to think of novel ways to improve themselves. That was the last piece. This is directly analogous to the ability to think of strange, alien ways to solve math problems: solutions so inhuman that they are difficult to express in existing human terms, so the proof winds up incomprehensible. I think these same kinds of alien solutions are now being applied to model improvements internally. That's what all this recent consternation is really about. They see the invisible frontier. And they see what is about to happen.
Robert Penner retweeted
I suggest that the right attitude to take toward the OpenAI math release is to imagine we have discovered a notebook full of results from a deceased mathematician. Our job it to make sense of the notebook.
The Real Mathematicians are vexed, terribly vexed that OpenAI did proofs without their permission.
It's math pandemonium!
ahmath.org/statements
It's official! Speed up dev by 6%, for the low, low cost of throwing away your regression suite.
ok it's official... AI-written unit tests and integration tests are empirically proven to be unhelpful. you should tell your agents to stop writing tests by themselves
on the deepswe eval set, banning sonnet 5.5 high from writing any tests actually resulted in slightly higher success rate (non stat-sig), with less time and token spent (stat-sig). this is pretty hard empirical evidence
across the tests that were written by the "tests allowed" baseline arm, 65% of them were unit tests, 35% were integration tests, neither bucket resulted in any improvement compared to not writing any tests at all
i also picked a random sample of 44 tasks subset where i completely disabled executing even existing tests - it also did not affect success rate at all
i spot checked many tests written in the baseline arm, and my intuition is that most tests are simply a repetition of the implementation
agent-written tests do not add any value because both the implementation and the tests were simply the agent's interpretation of our intent. the tests aren't any more accurate than the implementation itself
i suspect we can still extract some value from unit tests and integration tests if we describe them ourselves when we believe we can articulate our intent better through test cases than through requirements. but i have not proven this yet
also worth noting, during deepswe eval the agent wrote almost no e2e tests (only 17, compared to 3000+ unit/integration tests written). so this analysis does not prove nor disprove the value of e2e tests - i will do another eval specifically for that
Robert Penner retweeted
One little trick to make your codebase more readable:
* Install cccc github.com/moznion/cccc
* Configure it with max-cognitize and max-cyclomatic 40
* In AGENTS.md, instruct to validate that cccc passes
* Have one agent in ultracode refactor everything until cccc passes
🤩
Robert Penner retweeted
Systematically deriving efficient programs from specifications with formally verified step-by-step transformations was a beautiful idea from the 80s from Richard Bird Lambert Meertens. With the advent of AI coding agents and AI theorem provers its time has finally come. I think this can form the basis of AI coding agents that generate correct by construction code accompanied by the working out that explains its derivation to a human (or another agent). The linked article reproduces one of Richard Bird’s classic examples in Lean 4, along with proofs and performance results.
satnam6502.github.io/bird-me…
Robert Penner retweeted
1000% this
If you're "one-shotting" animations with Opus 5.5, the default output is slop (impressive slop but still):
- Pacing & animations are way too fast
- Too many effects (less is more!)
- No cohesion (movement in all directions)
- No focal point (where to draw attention?)
- Generic easing applied everywhere
- No consistent choreography
- Motion without meaning
Good animation explains something. Default animation is just meaningless eye candy.
"A React hook census found 6,900 hooks re-rendering on every keystroke."
It's like watching Hoarders: how do people let it get that bad?
We made claude.ai 3x faster in two weeks.
Here’s how we use Claude to measure, debug and improve performance. Prompts and methods included.
claude.dev/blog/how-we-made-…
Robert Penner retweeted
“The life you seek is hidden inside the discipline you avoid.”
- Epictetus
Despite being born into slavery, Epictetus rose to become one of history’s most influential Stoic philosophers. He believed that genuine freedom does not come from having an easier life, but from developing the ability to master yourself.
His teachings emphasized a challenging yet powerful principle: while you cannot determine everything that happens around you, you can choose your reactions, guide your decisions, and remain persistent when confronted with adversity.
“The life you seek is hidden inside the discipline you avoid.”
Although this quotation has no verified connection to Epictetus, its message reflects a central theme of Stoic philosophy. The future you desire may depend on confronting the responsibilities you repeatedly put off, whether that means exercising when you lack motivation, completing difficult tasks, or finally making the uncomfortable choices you have been avoiding.
#Jev AI is a non-verbal savant.
No circuits wasted on social skills.
Just 100% focus: melt that Scantron.
@typesafeai


























