Arnaud Spiwack
@aspiwack.bsky.social
Multi-classed Software Engineer/Constructive Mathematician. Sometimes plays video games sort of fast. Puts topoi in your computer.
Pinned
Arnaud Spiwack
@aspiwack.bsky.social
· Nov 17
👋 Welcome (numerous) newcomers.
I'm a Tokyo-based, French, polyglot software engineer, computer scientist, mathematician, and hobbyist speedrunner.
I generally speak of programming languages and their theory, linguistics, science, video games, movies, books. And how the world is very funny indeed.
I'm a Tokyo-based, French, polyglot software engineer, computer scientist, mathematician, and hobbyist speedrunner.
I generally speak of programming languages and their theory, linguistics, science, video games, movies, books. And how the world is very funny indeed.
It would seem that Netflix just added some seasons of Bones to their roster. I suppose it's a good time as any to share how much I hate this series. I picked up the series (I don't remember when) because David Boreanaz is a ton and a half of fun. 1/9
February 9, 2026 at 12:02 PM
It would seem that Netflix just added some seasons of Bones to their roster. I suppose it's a good time as any to share how much I hate this series. I picked up the series (I don't remember when) because David Boreanaz is a ton and a half of fun. 1/9
Somewhere at the back of my mind, always, are lurking questions about presheaf models of linear λ-calculus. Ready to pounce when I least expect it. 1/6
February 9, 2026 at 6:16 AM
Somewhere at the back of my mind, always, are lurking questions about presheaf models of linear λ-calculus. Ready to pounce when I least expect it. 1/6
Seeing stuff lie Orbitals, it occurs to me that the evolution of 3D animation is to look more and more like 2D animation. And it now reached the point where it only looks slightly worse www.youtube.com/watch?v=qGGR...
Orbitals – Nintendo Direct: Partner Showcase 2.5.2026
Orbitals is coming exclusively to Nintendo Switch 2 in summer 2026!
Team up in this 2-player co-op adventure as Maki and Omura and use your wits to overcome the odds in a retro anime-inspired…
www.youtube.com
February 7, 2026 at 12:48 PM
Seeing stuff lie Orbitals, it occurs to me that the evolution of 3D animation is to look more and more like 2D animation. And it now reached the point where it only looks slightly worse www.youtube.com/watch?v=qGGR...
Reposted by Arnaud Spiwack
Sir Ian McKellen performing a monologue from Shakespeare’s Sir Thomas More on the Stephen Colbert show. Never have I heard this monologue performed with such a keen sense of prescience. Nor have I ever been in this exact historical moment.TY Sir Ian, for reaching us once again.
#Pinks #ProudBlue
#Pinks #ProudBlue
February 5, 2026 at 11:50 AM
Sir Ian McKellen performing a monologue from Shakespeare’s Sir Thomas More on the Stephen Colbert show. Never have I heard this monologue performed with such a keen sense of prescience. Nor have I ever been in this exact historical moment.TY Sir Ian, for reaching us once again.
#Pinks #ProudBlue
#Pinks #ProudBlue
Reposted by Arnaud Spiwack
It seems we missed the release of the #ICFP videos.
Here is our own @aspiwack.bsky.social presenting his joint work with Thomas Bagrel on the Destination Calculus www.youtube.com/watch?v=zjAE...
Here is our own @aspiwack.bsky.social presenting his joint work with Thomas Bagrel on the Destination Calculus www.youtube.com/watch?v=zjAE...
[OOPSLA'25] Destination calculus: A linear λ-calculus for purely functional memory writes
Destination Calculus: A Linear 𝜆-Calculus for Purely Functional Memory Writes (Video, OOPSLA1 2025)
Thomas Bagrel and Arnaud Spiwack
(Tweag, France / LORIA, France / Inria, France; Tweag,…
www.youtube.com
February 4, 2026 at 9:45 AM
It seems we missed the release of the #ICFP videos.
Here is our own @aspiwack.bsky.social presenting his joint work with Thomas Bagrel on the Destination Calculus www.youtube.com/watch?v=zjAE...
Here is our own @aspiwack.bsky.social presenting his joint work with Thomas Bagrel on the Destination Calculus www.youtube.com/watch?v=zjAE...
Reposted by Arnaud Spiwack
This watermark graffiti by street artist Mathieu Tremblin is, like, the best thing ever.
January 29, 2026 at 8:47 PM
This watermark graffiti by street artist Mathieu Tremblin is, like, the best thing ever.
Did I already recount this story? A very well-respected English professor once told me “you don't have a French accent at all”. And as I was struggling through my embarrassment to reply they continued “…but it's not a real English accent”.
L’exigence du parfait accent anglais c’est un truc très français, les anglophones sont beaucoup plus cools avec ça.
February 1, 2026 at 2:00 AM
Did I already recount this story? A very well-respected English professor once told me “you don't have a French accent at all”. And as I was struggling through my embarrassment to reply they continued “…but it's not a real English accent”.
Reposted by Arnaud Spiwack
MSN Messenger Emoticons in 2003
January 31, 2026 at 5:24 PM
MSN Messenger Emoticons in 2003
Something that I've just realised. In the category of presheaves over a monoidal category, 𝒚(a) ⊸ F is the shift-by-a modality: λx. F(x⊗a).
Where 𝒚 is the Yoneda embedding and ⊸ is the exponential for the Day convolution. 1/3
Where 𝒚 is the Yoneda embedding and ⊸ is the exponential for the Day convolution. 1/3
January 29, 2026 at 12:29 AM
Something that I've just realised. In the category of presheaves over a monoidal category, 𝒚(a) ⊸ F is the shift-by-a modality: λx. F(x⊗a).
Where 𝒚 is the Yoneda embedding and ⊸ is the exponential for the Day convolution. 1/3
Where 𝒚 is the Yoneda embedding and ⊸ is the exponential for the Day convolution. 1/3
One thing that modern language models show is that there can be a useful notion of lossy compression for text.
In a sense, these language models are the jpeg of text.
In a sense, these language models are the jpeg of text.
January 28, 2026 at 7:15 AM
One thing that modern language models show is that there can be a useful notion of lossy compression for text.
In a sense, these language models are the jpeg of text.
In a sense, these language models are the jpeg of text.
It makes me shudder every time. Maybe it's a French thing to dislike this pronunciation, I don't know. But I truly hate it.
✱ PSA: If you pronounce “bona fide” pretty much like “bonified”, you are a bunch of ignorami. 😜
No, seriously, “fide” has two syllables in Latin. Say it like “fee-day” in English. I can tolerate “feye-dee” on a good day, but if you think it rhymes with “mystified”, please don't say this around me.
No, seriously, “fide” has two syllables in Latin. Say it like “fee-day” in English. I can tolerate “feye-dee” on a good day, but if you think it rhymes with “mystified”, please don't say this around me.
Ah oui, j'ai beau ne pas être prescriptiviste en général, les anglophones qui prononcent «bona fide» en faisant une seule syllabe (😱) du second mot, ça me donne des pulsions de violence. J'ai longtemps cru qu'ils disaient «bonified» (participe passé de «bonify»).
January 28, 2026 at 12:03 AM
It makes me shudder every time. Maybe it's a French thing to dislike this pronunciation, I don't know. But I truly hate it.
I'm furious at myself.
I've discovered just this instant that Emacs's Reftex has a command to insert Cleveref's \cref commands. For *years* I've been inserting \ref and manually fixing. I discovered it by mistakenly typing cref in my completion engine.
Don't mind me, I'll be weeping in a corner.
I've discovered just this instant that Emacs's Reftex has a command to insert Cleveref's \cref commands. For *years* I've been inserting \ref and manually fixing. I discovered it by mistakenly typing cref in my completion engine.
Don't mind me, I'll be weeping in a corner.
January 27, 2026 at 7:14 AM
I'm furious at myself.
I've discovered just this instant that Emacs's Reftex has a command to insert Cleveref's \cref commands. For *years* I've been inserting \ref and manually fixing. I discovered it by mistakenly typing cref in my completion engine.
Don't mind me, I'll be weeping in a corner.
I've discovered just this instant that Emacs's Reftex has a command to insert Cleveref's \cref commands. For *years* I've been inserting \ref and manually fixing. I discovered it by mistakenly typing cref in my completion engine.
Don't mind me, I'll be weeping in a corner.
J'avoue, ça donne envie.
On est bien chez les matheux y'a des tableaux dans le jardin
January 25, 2026 at 11:05 PM
J'avoue, ça donne envie.
What a time we live in. On Twitter, what appears to be an official account of French diplomacy seems to be mostly shittposting. x.com/FrenchResponse
I'm torn between “this is no way for a government to behave” and “this is the right way to deal with international trolls in this and that place”.
I'm torn between “this is no way for a government to behave” and “this is the right way to deal with international trolls in this and that place”.
French Response (@FrenchResponse) / X
French Response (@FrenchResponse) / X
x.com
January 20, 2026 at 12:35 AM
What a time we live in. On Twitter, what appears to be an official account of French diplomacy seems to be mostly shittposting. x.com/FrenchResponse
I'm torn between “this is no way for a government to behave” and “this is the right way to deal with international trolls in this and that place”.
I'm torn between “this is no way for a government to behave” and “this is the right way to deal with international trolls in this and that place”.
I'm reminded of the French 2012 presidential election. I felt that even those who voted for him were relieved that Nicolas Sarkozy lost. His constant presence and occupation of the media landscape was positively exhausting.
I'm perfectly aware this is by far not the worst thing he's done, but Trump's constant presence - day after day after day - in the lives and headspaces of hundreds of millions of people (billions?), in the US and outside, is so taxing. Every morning, we wake up and have to think about this asshole.
January 20, 2026 at 12:00 AM
I'm reminded of the French 2012 presidential election. I felt that even those who voted for him were relieved that Nicolas Sarkozy lost. His constant presence and occupation of the media landscape was positively exhausting.
Reposted by Arnaud Spiwack
Followed by The Final Countdown played on assorted junk.
youtu.be/B4PSvN3VSyI?...
youtu.be/B4PSvN3VSyI?...
The Final Countdown (Europe) - Les Fo'Plafonds
YouTube video by Les Fo'Plafonds
youtu.be
January 16, 2026 at 10:19 PM
Followed by The Final Countdown played on assorted junk.
youtu.be/B4PSvN3VSyI?...
youtu.be/B4PSvN3VSyI?...
Reposted by Arnaud Spiwack
What your TL needs right now is the Star Wars Imperial March played on rubber chickens: www.youtube.com/shorts/PQhVt...
Imperial March on Rubber Chicken
YouTube video by Vinheteiro
www.youtube.com
January 16, 2026 at 9:49 PM
What your TL needs right now is the Star Wars Imperial March played on rubber chickens: www.youtube.com/shorts/PQhVt...
Reposted by Arnaud Spiwack
Reposted by Arnaud Spiwack
Reposted by Arnaud Spiwack
🧪 Here's a science mystery to start the year.
Why are species names for fish and plants appearing in the scientific literature in papers about firefighter injuries, hearing loss and heart attack?
Is it AI? Translation tools? Something else?
nobreakthroughs.substack.com/p/is-this-fi...
Why are species names for fish and plants appearing in the scientific literature in papers about firefighter injuries, hearing loss and heart attack?
Is it AI? Translation tools? Something else?
nobreakthroughs.substack.com/p/is-this-fi...
January 11, 2026 at 11:34 PM
🧪 Here's a science mystery to start the year.
Why are species names for fish and plants appearing in the scientific literature in papers about firefighter injuries, hearing loss and heart attack?
Is it AI? Translation tools? Something else?
nobreakthroughs.substack.com/p/is-this-fi...
Why are species names for fish and plants appearing in the scientific literature in papers about firefighter injuries, hearing loss and heart attack?
Is it AI? Translation tools? Something else?
nobreakthroughs.substack.com/p/is-this-fi...
Diminish a band
Rage Against the Machinima
Rage Against the Machinima
Diminish a band
Police (Municipale)
Police (Municipale)
Diminish a band
The Placo Maiden
The Placo Maiden
January 12, 2026 at 2:20 AM
Diminish a band
Rage Against the Machinima
Rage Against the Machinima
I'm quite happy about how this library turned out. I have good hope that it's going to be useful to you. Yes. You.
New year, new blog post. Arnaud Spiwack announces the Pup library. A Haskell library for combinators that do both parsing and pretty printing in a single grammar description. Read and discover the big ideas behind the library's design. www.tweag.io/blog/2026-01...
The quest for grammar combinators: introducing the Pup library
Announcing the Pup library.
www.tweag.io
January 9, 2026 at 7:39 AM
I'm quite happy about how this library turned out. I have good hope that it's going to be useful to you. Yes. You.
I'd like to contrast this to Dept Q, which I recently watched too. It has a very similar premise: the main character is typically described as “an arrogant prick”. But this series is fantastic, not in small part because the characters feel like characters.
The result is that the season consists mostly of Wednesday being angry and claiming herself perfect, and the rest of the cast lecturing her about it. Over, and over. And it doesn't even amount to anything. If other characters are allowed a modicum of growth, not Wednesday. 2/15
January 8, 2026 at 6:50 AM
I'd like to contrast this to Dept Q, which I recently watched too. It has a very similar premise: the main character is typically described as “an arrogant prick”. But this series is fantastic, not in small part because the characters feel like characters.
Reposted by Arnaud Spiwack
This etymology is wild!
#TIL The English word “average”, originally “custom duty” or “loss in transported goods”, comes from the French “avarie” (meaning “damage to a ship or cargo”) from the Italian “avaria” (same meaning), …
#TIL The English word “average”, originally “custom duty” or “loss in transported goods”, comes from the French “avarie” (meaning “damage to a ship or cargo”) from the Italian “avaria” (same meaning), …
January 7, 2026 at 12:34 AM
This etymology is wild!
#TIL The English word “average”, originally “custom duty” or “loss in transported goods”, comes from the French “avarie” (meaning “damage to a ship or cargo”) from the Italian “avaria” (same meaning), …
#TIL The English word “average”, originally “custom duty” or “loss in transported goods”, comes from the French “avarie” (meaning “damage to a ship or cargo”) from the Italian “avaria” (same meaning), …
There are more nuances to this story that I still don't get either.
If you look at the definition of realisers of A->B, it's not the function space of A to B: it's only those function which are represented by a term. 1/3
If you look at the definition of realisers of A->B, it's not the function space of A to B: it's only those function which are represented by a term. 1/3
I keep thinking about realisability for linear types, and how it seems important that it takes semantics in every presheaf category. Or maybe not all, but all those where the base category admits is a product with a certain category. 1/2
January 7, 2026 at 1:52 PM
There are more nuances to this story that I still don't get either.
If you look at the definition of realisers of A->B, it's not the function space of A to B: it's only those function which are represented by a term. 1/3
If you look at the definition of realisers of A->B, it's not the function space of A to B: it's only those function which are represented by a term. 1/3