HackerReposA FIELD GUIDE TO OPEN SOURCE
ProSponsor the shelf♧ 0
← Back to top all-time
barry-jay-personal
typed_tree_calculus
Rocq Prover2024–2026
barry-jay-personal / typed_tree_calculus

typed_tree_calculus

types for various combinatory systems, especialy tree calculi

6Distinct people
6Mentions
0Explicit recommenders
30GitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

types for various combinatory systems, especialy tree calculi

GitHub

Where it is used

No documented product use has been verified yet.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

No other repository is repeatedly linked in the same discussions.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:56:07 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by month6 dated mentions

Observed mentions: 2024-12-10 11:36:05 UTC to 2026-10-17 13:15:12 UTC.

0122024-12-01 00:00:00 UTC to 2025-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 commentsDec 20242025-01-01 00:00:00 UTC to 2025-02-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-02-01 00:00:00 UTC to 2025-03-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-03-01 00:00:00 UTC to 2025-04-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-04-01 00:00:00 UTC to 2025-05-01 00:00:00 UTC (exclusive): 1 mentions; 1 submissions, 0 comments2025-05-01 00:00:00 UTC to 2025-06-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-06-01 00:00:00 UTC to 2025-07-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-07-01 00:00:00 UTC to 2025-08-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-08-01 00:00:00 UTC to 2025-09-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-09-01 00:00:00 UTC to 2025-10-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-10-01 00:00:00 UTC to 2025-11-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2025-11-01 00:00:00 UTC to 2025-12-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 commentsNov 20252025-12-01 00:00:00 UTC to 2026-01-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2026-01-01 00:00:00 UTC to 2026-02-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2026-02-01 00:00:00 UTC to 2026-03-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2026-03-01 00:00:00 UTC to 2026-04-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2026-04-01 00:00:00 UTC to 2026-05-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2026-05-01 00:00:00 UTC to 2026-06-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2026-06-01 00:00:00 UTC to 2026-07-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2026-07-01 00:00:00 UTC to 2026-08-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2026-08-01 00:00:00 UTC to 2026-09-01 00:00:00 UTC (exclusive): 0 mentions; 0 submissions, 0 comments2026-09-01 00:00:00 UTC to 2026-10-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments2026-10-01 00:00:00 UTC to 2026-11-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 commentsOct 2026

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
Dec 20242024-12-01 00:00:00 UTC2025-01-01 00:00:00 UTC202
Jan 20252025-01-01 00:00:00 UTC2025-02-01 00:00:00 UTC000
Feb 20252025-02-01 00:00:00 UTC2025-03-01 00:00:00 UTC000
Mar 20252025-03-01 00:00:00 UTC2025-04-01 00:00:00 UTC000
Apr 20252025-04-01 00:00:00 UTC2025-05-01 00:00:00 UTC110
May 20252025-05-01 00:00:00 UTC2025-06-01 00:00:00 UTC000
Jun 20252025-06-01 00:00:00 UTC2025-07-01 00:00:00 UTC000
Jul 20252025-07-01 00:00:00 UTC2025-08-01 00:00:00 UTC000
Aug 20252025-08-01 00:00:00 UTC2025-09-01 00:00:00 UTC000
Sep 20252025-09-01 00:00:00 UTC2025-10-01 00:00:00 UTC000
Oct 20252025-10-01 00:00:00 UTC2025-11-01 00:00:00 UTC000
Nov 20252025-11-01 00:00:00 UTC2025-12-01 00:00:00 UTC000
Dec 20252025-12-01 00:00:00 UTC2026-01-01 00:00:00 UTC000
Jan 20262026-01-01 00:00:00 UTC2026-02-01 00:00:00 UTC000
Feb 20262026-02-01 00:00:00 UTC2026-03-01 00:00:00 UTC000
Mar 20262026-03-01 00:00:00 UTC2026-04-01 00:00:00 UTC000
Apr 20262026-04-01 00:00:00 UTC2026-05-01 00:00:00 UTC000
May 20262026-05-01 00:00:00 UTC2026-06-01 00:00:00 UTC000
Jun 20262026-06-01 00:00:00 UTC2026-07-01 00:00:00 UTC000
Jul 20262026-07-01 00:00:00 UTC2026-08-01 00:00:00 UTC000
Aug 20262026-08-01 00:00:00 UTC2026-09-01 00:00:00 UTC000
Sep 20262026-09-01 00:00:00 UTC2026-10-01 00:00:00 UTC202
Oct 20262026-10-01 00:00:00 UTC2026-11-01 00:00:00 UTC101

What Hacker News says

6 sources
I'd never heard of Cubical Type Theory, how interesting. Aside from that, and Mikan - why they forked, their development/contribution policy (which I happen to agree with more or less); and the notion of equality and equivalence (you didn't use this word but I read an article¹ with a glimpse into these concepts).. "Equalities are paths" - I'm going to be thinking about that for a while. Anyway the link to 1lab and the comments in this thread gave me various ideas to chew on, there's lot of substance there. On the 1lab site, I started with simply-typed lambda calculus, an all-time classic that I've always wanted to understand more fully. How the site is designed, I love the syntax-highlighted math/code and the interface where every single concept can be clicked and hovered over to show additional information with usually a link to its own
Read the rest
page. It led me to a kind of branching, graph-like manner of learning, where I open pages on categories, products, morphisms, uniqueness, equality - filling holes in my understanding as needed, then going back to more specific ideas built from those general foundational concepts. An interactive textbook as a computational medium I feel has a lot more potential for usefulness and expression, to support an autodidactic and exploratory style of learning. It relates to topics raised elsewhere in this thread, like a "proper IDE for math" (integrated development environment for mathematics) and a language-agnostic "standard library" of data structures, algorithms, definitions, theorems, etc., where programming languages can import from a shared corpus of mathematically rigorous primitives. > how to use dependent types to explore, teach, and formalize mathematics in a pro-human way I find it meaningful how you phrased this - at this point in history with the state of technology that can overwhelm and devalue human intelligence, it's more important than ever to focus on how we teach, learn, communicate and cultivate understanding. On a tangent, one of my interests is the book _Reflective Programs in Tree Calculus_² by Barry Jay, its proofs in Rocq, his more recent article "Typed Program Analysis without Encodings"³, and the work of his main collaborator⁴. I lack the relevant academic background to fully grasp it yet, so I've been chipping away at learning the necessary basics. So the link to 1lab is appreciated, it's a resource I'll be digging into over time. --- ¹ With Category Theory, Mathematics Escapes From Equality https://www.quantamagazine.org/with-category-theory-mathemat... ² https://github.com/barry-jay-personal/tree-calculus/blob/mas... (PDF) ³ https://github.com/barry-jay-personal/typed_tree_calculus/bl... (PDF) ⁴ https://github.com/lambada-llc/tree-calculus
In How to Formalize All of Mathematics
>Great notes! Thank you! >I think it’s also worth noting that Barry Jay has a particularly strong vantage point for unearthing this particular foundational candidate. First, his advisor was Joachim Lambek, who’s responsible for adding Category Theory in the Curry-Howard-Lambek correspondence. Curry-Howard-Lambek correspondence is a very important point, I'm glad you brought it up! >If one looks at Barry’s body of work over his lifetime, it’s no surprise it would culminate into an elegantly beautiful system capable of self-reflection. No, it's not surprising indeed! >I think his 2025 PEPM paper did a great job explaining the ideas to a regular programmer / wannabe academic like myself: https://github.com/barry-jay-personal/typed_tree_calculus/bl... Excellent link! Random thought: From the paper: "The operator [Triangle] (pronounced "node")
Read the rest
is a ternary operator)..." I wonder if Tree Calculus (and/or binary trees in general!) could be related to, and/or applied to the Ternary Tau and/or the Balanced Phinary number systems: https://neuraloutlet.wordpress.com/tag/ternary-tau-system/ https://en.wikipedia.org/wiki/Balanced_ternary
In Tree Calculus
Great notes! I think it’s also worth noting that Barry Jay has a particularly strong vantage point for unearthing this particular foundational candidate. First, his advisor was Joachim Lambek, who’s responsible for adding Category Theory in the Curry-Howard-Lambek correspondence. If one looks at Barry’s body of work over his lifetime, it’s no surprise it would culminate into an elegantly beautiful system capable of self-reflection. I think his 2025 PEPM paper did a great job explaining the ideas to a regular programmer / wannabe academic like myself: https://github.com/barry-jay-personal/typed_tree_calculus/bl...
In Tree Calculus
Hi all, author of the website here (I'm https://johannes-bader.com/). Wow, thanks for the reactions and many good suggestions! I thought I'd add a bit of context here. As has correctly been pointed out, Tree Calculus was developed by Barry Jay! The "Specification" page links to his book. And a preview of his PEPM 2025 paper (hi chewxy!) can now be found here: https://github.com/barry-jay-personal/typed_tree_calculus/bl... Compared to how long Barry has been professionally researching this, I entered the picture yesterday and joined the effort to help. Potential mistakes on the website are mine, not Barry's, but I do firmly believe in some of the "ambitious" wording there. Blog posts and more concrete demos or details to come! Just for the curious, here is my angle in all this: I happened to (hobbyist!) research tiny, yet practical, langua
Read the rest
ges for over a decade (see e.g. https://lambada.pages.dev/). In that work I started noticing that the Iota combinator (https://en.wikipedia.org/wiki/Iota_and_Jot) is not a combinator in the most traditional sense: It is usually defined as behaving like "\x x S K", but like, how can we just refer to a lambda in the definition of a logic? One could write reduction rules such as "Iota Iota x -> x", but now Iota appears on the left hand side, in argument position! Doesn't that allow reflecting on arguments? Horror! I just started realizing that, while SK is perfectly Turing complete and sane, forcing down the number of combinators from 2 to 1 magically forces some amount of intensionality! Curious, isn't it? And that's when I came across Barry's work and book! A calculus that embraces intensionality. So I reached out to see if I can help. How can I be most useful? Barry has been figuring out theory, professionally, before I could think. So I felt like helping spread the word, maybe to a less academic developer crowd, would be a more effective way to contribute. I spent my entire career building developer tools, so I have some ideas what could be useful and what might be necessary to convince various kinds of developers. That's how the website came to be, and it is very much a work in progress. We sync regularly, for instance Barry had excellent ideas for demos and I suggested slightly tweaked reduction rules at some point (not more powerful in theory, just more convenient in practice), see "triage calculus" in typed_program_analysis.pdf
In Tree Calculus

MAKE YOURSELF AT HOME

A few shortcuts

/
Search the collection
?
Open this guide
Esc
Close dialogs and navigation

Your saved repositories and interests stay in this browser.