Tikhon Jelvis
@jelv.is
I like programming languages. A lot. Especially Haskell.
Tools, types and functions.
Tools, types and functions.
hot take: "most technical problems are people problems" is not some fundamental truth, but rather a reflection of our dominant organizations and organizational culture
December 5, 2025 at 9:33 PM
hot take: "most technical problems are people problems" is not some fundamental truth, but rather a reflection of our dominant organizations and organizational culture
Reposted by Tikhon Jelvis
I will die on the hill that if "the median score of people who use a particular accommodation" is that much higher than "the median score of people who don't use a particular accommodation" it is a sign that the instrument you are using is measuring the wrong thing
December 4, 2025 at 5:00 PM
I will die on the hill that if "the median score of people who use a particular accommodation" is that much higher than "the median score of people who don't use a particular accommodation" it is a sign that the instrument you are using is measuring the wrong thing
Reposted by Tikhon Jelvis
(In fact if you see a major bump in score outcomes via accommodations what you are very likely seeing is a gatekeeping event, not a knowledge test.)
December 4, 2025 at 5:22 PM
(In fact if you see a major bump in score outcomes via accommodations what you are very likely seeing is a gatekeeping event, not a knowledge test.)
We cross our bridges when we come to them and burn them behind us, with nothing to show for our progress except a memory of the smell of smoke, and a presumption that once our eyes watered.
December 2, 2025 at 4:10 AM
We cross our bridges when we come to them and burn them behind us, with nothing to show for our progress except a memory of the smell of smoke, and a presumption that once our eyes watered.
Being good at something and being good at building tools—libraries, DSLs, etc—for something are surprisingly different skills.
A lot of teams need the latter but hire and incentivize the former.
A lot of teams need the latter but hire and incentivize the former.
November 30, 2025 at 8:26 PM
Being good at something and being good at building tools—libraries, DSLs, etc—for something are surprisingly different skills.
A lot of teams need the latter but hire and incentivize the former.
A lot of teams need the latter but hire and incentivize the former.
Reposted by Tikhon Jelvis
Yknow, I never see anyone talk about this side effect of “personalization”—people are weird, and it turns out that it’s hard* to make massive amounts of advertising money catering to specific interests. So platforms have re-created a boring middle, shoved us all into it, and claim it’s “targeted.”
I wrote a bit about this many years ago on Twitter-that-was: the algorithm has gradually eroded "here's what you want to see" by replacing it with "here's what we'd like you to want to see."
It continues to trade on its former reputation solely due to inertia. Underneath, it's all ads.
It continues to trade on its former reputation solely due to inertia. Underneath, it's all ads.
love to live in a world where all my personal data is relentlessly harvested so that megacorps can feed it into their all-knowing algorithms and yet somehow the end result is that algorithm going “we think you’d like Clarkson’s Farm”
November 28, 2025 at 12:07 PM
Yknow, I never see anyone talk about this side effect of “personalization”—people are weird, and it turns out that it’s hard* to make massive amounts of advertising money catering to specific interests. So platforms have re-created a boring middle, shoved us all into it, and claim it’s “targeted.”
Reposted by Tikhon Jelvis
🎉 Unison 1.0 has landed!
After years of engineering, design, and community collaboration, we’re excited to announce this milestone!
Spread the word!
After years of engineering, design, and community collaboration, we’re excited to announce this milestone!
Spread the word!
Announcing Unison 1.0
After years of engineering, design, and community collaboration, we're excited to release Unison 1.0. This version delivers a refined programming workflow and a mature toolchain. Join us as we celebrate this milestone and look ahead to the future of Unison.
www.unison-lang.org
November 25, 2025 at 7:01 PM
🎉 Unison 1.0 has landed!
After years of engineering, design, and community collaboration, we’re excited to announce this milestone!
Spread the word!
After years of engineering, design, and community collaboration, we’re excited to announce this milestone!
Spread the word!
Reposted by Tikhon Jelvis
Assessing the quality of a random number generator is luckily quite simple. Every time it gives you a value, ask yourself: did I expect this to happen?
November 18, 2025 at 9:13 PM
Assessing the quality of a random number generator is luckily quite simple. Every time it gives you a value, ask yourself: did I expect this to happen?
Gödel's incompleteness theorems prove that everything is made up and the points don't matter.
November 18, 2025 at 4:08 AM
Gödel's incompleteness theorems prove that everything is made up and the points don't matter.
Reposted by Tikhon Jelvis
a joyful discovery today: prefix sum `sum[l,r]=sum[r]-sum[l]` can be generalized to arbitrary group, some of which are good-enough hashes which can be used in subsequence searching. this is exactly the rabin-karp algorithm, but online materials about it seldom mention group theory at all
November 17, 2025 at 3:25 PM
a joyful discovery today: prefix sum `sum[l,r]=sum[r]-sum[l]` can be generalized to arbitrary group, some of which are good-enough hashes which can be used in subsequence searching. this is exactly the rabin-karp algorithm, but online materials about it seldom mention group theory at all
A realization I've had: programming languages are as much tools managing complexity (ie design + abstraction) as they are for telling computers what to do—and mixing both together is critical for being good at the former.
(And PLs are amazing at handling complexity!)
(And PLs are amazing at handling complexity!)
November 6, 2025 at 8:44 PM
A realization I've had: programming languages are as much tools managing complexity (ie design + abstraction) as they are for telling computers what to do—and mixing both together is critical for being good at the former.
(And PLs are amazing at handling complexity!)
(And PLs are amazing at handling complexity!)
Reposted by Tikhon Jelvis
📣THREAD: It’s surprising to me that so many people were surprised to learn that Signal runs partly on AWS (something we can do because we use encryption to make sure no one but you–not AWS, not Signal, not anyone–can access your comms).
It’s also concerning. 1/
It’s also concerning. 1/
PSA: we're aware that Signal is down for some people. This appears to be related to a major AWS outage. Stand by.
October 27, 2025 at 10:38 AM
📣THREAD: It’s surprising to me that so many people were surprised to learn that Signal runs partly on AWS (something we can do because we use encryption to make sure no one but you–not AWS, not Signal, not anyone–can access your comms).
It’s also concerning. 1/
It’s also concerning. 1/
Reposted by Tikhon Jelvis
On certainty of outputs: the Fordist instinct to demand "when will thing be Done" serves no purpose beyond dashboard/report curation, which has replaced actual management work in most orgs. It displaces all other value of the thing except for Done-ness. My Button talk on Thursday is about this.
October 21, 2025 at 3:43 PM
On certainty of outputs: the Fordist instinct to demand "when will thing be Done" serves no purpose beyond dashboard/report curation, which has replaced actual management work in most orgs. It displaces all other value of the thing except for Done-ness. My Button talk on Thursday is about this.
Reposted by Tikhon Jelvis
I designed a cover for Samuel Delany's DHALGREN because the cover of the edition I'm reading is boring.
October 15, 2025 at 7:24 PM
I designed a cover for Samuel Delany's DHALGREN because the cover of the edition I'm reading is boring.
random bit of nostalgia: libraries here used to have TUIs for searching the catalog, and it definitely gave them some real gravitas
it definitely impressed me as a middle schooler :P
it definitely impressed me as a middle schooler :P
October 15, 2025 at 3:59 PM
random bit of nostalgia: libraries here used to have TUIs for searching the catalog, and it definitely gave them some real gravitas
it definitely impressed me as a middle schooler :P
it definitely impressed me as a middle schooler :P
Reposted by Tikhon Jelvis
New blog post: The illegible nature of software development talent
surfingcomplexity.blog/2025/10/08/t...
surfingcomplexity.blog/2025/10/08/t...
The illegible nature of software development talent
Here’s another blog post on gathering some common threads from reading recent posts. Today’s topic is about the unassuming nature of talented software engineers. The first thread was a …
surfingcomplexity.blog
October 9, 2025 at 5:17 AM
New blog post: The illegible nature of software development talent
surfingcomplexity.blog/2025/10/08/t...
surfingcomplexity.blog/2025/10/08/t...
this is one of those things where I can't tell whether it's so obvious nobody even bothers talking about it, or it's not obvious at all to most people :/
I'm sure I said this (lack of formal data/code distinction) should have been obvious several months ago and we're only just seeing papers and articles coming out saying "huh, turns out"
Large language models have a pretty fundamental flaw: they don't distinguish between data and code. On its own, that might be embarrassing (think helpbots writing dirty limericks) but get the wrong set of capabilities in the mix and a fancy new AI tool can become a dangerous security vulnerability.
September 23, 2025 at 12:18 PM
this is one of those things where I can't tell whether it's so obvious nobody even bothers talking about it, or it's not obvious at all to most people :/
Reposted by Tikhon Jelvis
I was doing some software history research and stumbled on this absolutely FASCINATING letter from 1964: dl.acm.org/doi/10.1145/...
Some random defense contractor writes in to say "You should deliver a minimal prototype as fast as possible to get feedback and involve users at every stage of labor"
Some random defense contractor writes in to say "You should deliver a minimal prototype as fast as possible to get feedback and involve users at every stage of labor"
Some observations concerning large programming efforts | Proceedings of the April 21-23, 1964, spring joint computer conference
dl.acm.org
September 22, 2025 at 8:40 PM
I was doing some software history research and stumbled on this absolutely FASCINATING letter from 1964: dl.acm.org/doi/10.1145/...
Some random defense contractor writes in to say "You should deliver a minimal prototype as fast as possible to get feedback and involve users at every stage of labor"
Some random defense contractor writes in to say "You should deliver a minimal prototype as fast as possible to get feedback and involve users at every stage of labor"
Do I know anyone around Gdansk?
I'll be hanging around the area for the next week or two, would be great to meet up for lunch/tea/etc
I'll be hanging around the area for the next week or two, would be great to meet up for lunch/tea/etc
September 20, 2025 at 9:57 PM
Do I know anyone around Gdansk?
I'll be hanging around the area for the next week or two, would be great to meet up for lunch/tea/etc
I'll be hanging around the area for the next week or two, would be great to meet up for lunch/tea/etc
Empirically studying the effectiveness of static typing is incredibly difficult—and I actually find that reassuring.
(The thread before the quoted post is also worth reading!)
(The thread before the quoted post is also worth reading!)
In some ways, I find it reassuring.
It underscores how programming is fundamentally creative, high-leverage—and therefore illegible—work.
If only more industry leaders would recognize this too...
It underscores how programming is fundamentally creative, high-leverage—and therefore illegible—work.
If only more industry leaders would recognize this too...
September 20, 2025 at 3:45 PM
Empirically studying the effectiveness of static typing is incredibly difficult—and I actually find that reassuring.
(The thread before the quoted post is also worth reading!)
(The thread before the quoted post is also worth reading!)
Reposted by Tikhon Jelvis
#AmeriHac – The hackathon by the #Haskell Foundation in New York City has been announced for the 7th and 8th of February 2026!
discourse.haskell.org/t/the-inaugu...
discourse.haskell.org/t/the-inaugu...
The Inaugural North America Haskell Hackathon
North American Hackathon The Haskell Foundation is proud to announce the inaugural AmeriHac, a two day haskell hackathon, with this iteration being in New York City! Jane Street has kindly offered to ...
discourse.haskell.org
September 13, 2025 at 4:39 PM
#AmeriHac – The hackathon by the #Haskell Foundation in New York City has been announced for the 7th and 8th of February 2026!
discourse.haskell.org/t/the-inaugu...
discourse.haskell.org/t/the-inaugu...
one of the things that finally got me to consider I have ADHD was catching myself painfully procrastinating on... starting a video game I was legitimately excited about >.<
Some of the biggest ADHD struggles are often getting ourselves to do the things we desperately want to do
September 6, 2025 at 5:43 PM
one of the things that finally got me to consider I have ADHD was catching myself painfully procrastinating on... starting a video game I was legitimately excited about >.<
performative hours ≠ excitement
if folks were actually excited and motivated, you wouldn't need forced hours, you'd just trust people to work in the best way for them
if folks were actually excited and motivated, you wouldn't need forced hours, you'd just trust people to work in the best way for them
September 6, 2025 at 5:23 PM
performative hours ≠ excitement
if folks were actually excited and motivated, you wouldn't need forced hours, you'd just trust people to work in the best way for them
if folks were actually excited and motivated, you wouldn't need forced hours, you'd just trust people to work in the best way for them
programming languages aren't just tools for making computers do stuff but also remarkably good as tools for conceptual design
fluidly mixing design and execution is part of what makes them so good at managing complexity because that lets us build hierarchies of concepts
fluidly mixing design and execution is part of what makes them so good at managing complexity because that lets us build hierarchies of concepts
September 4, 2025 at 4:43 PM
programming languages aren't just tools for making computers do stuff but also remarkably good as tools for conceptual design
fluidly mixing design and execution is part of what makes them so good at managing complexity because that lets us build hierarchies of concepts
fluidly mixing design and execution is part of what makes them so good at managing complexity because that lets us build hierarchies of concepts
my optimistic case for LLMs:
the world today is held together with Excel because Excel, for all its faults, lets its user adapt the tool to their needs rather than adapting their needs to their tools
LLMs aren't there today, but they might be the foundation for the next Excel
the world today is held together with Excel because Excel, for all its faults, lets its user adapt the tool to their needs rather than adapting their needs to their tools
LLMs aren't there today, but they might be the foundation for the next Excel
August 28, 2025 at 6:00 AM
my optimistic case for LLMs:
the world today is held together with Excel because Excel, for all its faults, lets its user adapt the tool to their needs rather than adapting their needs to their tools
LLMs aren't there today, but they might be the foundation for the next Excel
the world today is held together with Excel because Excel, for all its faults, lets its user adapt the tool to their needs rather than adapting their needs to their tools
LLMs aren't there today, but they might be the foundation for the next Excel