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OpenCiv3: Open-source, cross-platform reimagining of Civilization III

https://openciv3.org/
623•klaussilveira•12h ago•182 comments

The Waymo World Model

https://waymo.com/blog/2026/02/the-waymo-world-model-a-new-frontier-for-autonomous-driving-simula...
924•xnx•18h ago•548 comments

What Is Ruliology?

https://writings.stephenwolfram.com/2026/01/what-is-ruliology/
32•helloplanets•4d ago•24 comments

How we made geo joins 400× faster with H3 indexes

https://floedb.ai/blog/how-we-made-geo-joins-400-faster-with-h3-indexes
109•matheusalmeida•1d ago•27 comments

Jeffrey Snover: "Welcome to the Room"

https://www.jsnover.com/blog/2026/02/01/welcome-to-the-room/
9•kaonwarb•3d ago•7 comments

Unseen Footage of Atari Battlezone Arcade Cabinet Production

https://arcadeblogger.com/2026/02/02/unseen-footage-of-atari-battlezone-cabinet-production/
40•videotopia•4d ago•1 comments

Show HN: Look Ma, No Linux: Shell, App Installer, Vi, Cc on ESP32-S3 / BreezyBox

https://github.com/valdanylchuk/breezydemo
219•isitcontent•12h ago•25 comments

Monty: A minimal, secure Python interpreter written in Rust for use by AI

https://github.com/pydantic/monty
209•dmpetrov•13h ago•103 comments

Show HN: I spent 4 years building a UI design tool with only the features I use

https://vecti.com
320•vecti•15h ago•142 comments

Sheldon Brown's Bicycle Technical Info

https://www.sheldonbrown.com/
369•ostacke•18h ago•94 comments

Microsoft open-sources LiteBox, a security-focused library OS

https://github.com/microsoft/litebox
357•aktau•19h ago•181 comments

Hackers (1995) Animated Experience

https://hackers-1995.vercel.app/
477•todsacerdoti•20h ago•232 comments

Show HN: If you lose your memory, how to regain access to your computer?

https://eljojo.github.io/rememory/
272•eljojo•15h ago•160 comments

An Update on Heroku

https://www.heroku.com/blog/an-update-on-heroku/
402•lstoll•19h ago•271 comments

Dark Alley Mathematics

https://blog.szczepan.org/blog/three-points/
85•quibono•4d ago•20 comments

Vocal Guide – belt sing without killing yourself

https://jesperordrup.github.io/vocal-guide/
14•jesperordrup•2h ago•6 comments

Delimited Continuations vs. Lwt for Threads

https://mirageos.org/blog/delimcc-vs-lwt
25•romes•4d ago•3 comments

PC Floppy Copy Protection: Vault Prolok

https://martypc.blogspot.com/2024/09/pc-floppy-copy-protection-vault-prolok.html
56•kmm•5d ago•3 comments

Was Benoit Mandelbrot a hedgehog or a fox?

https://arxiv.org/abs/2602.01122
12•bikenaga•3d ago•2 comments

How to effectively write quality code with AI

https://heidenstedt.org/posts/2026/how-to-effectively-write-quality-code-with-ai/
243•i5heu•15h ago•187 comments

Introducing the Developer Knowledge API and MCP Server

https://developers.googleblog.com/introducing-the-developer-knowledge-api-and-mcp-server/
52•gfortaine•10h ago•21 comments

I spent 5 years in DevOps – Solutions engineering gave me what I was missing

https://infisical.com/blog/devops-to-solutions-engineering
139•vmatsiiako•17h ago•62 comments

Understanding Neural Network, Visually

https://visualrambling.space/neural-network/
280•surprisetalk•3d ago•37 comments

I now assume that all ads on Apple news are scams

https://kirkville.com/i-now-assume-that-all-ads-on-apple-news-are-scams/
1058•cdrnsf•22h ago•433 comments

Why I Joined OpenAI

https://www.brendangregg.com/blog/2026-02-07/why-i-joined-openai.html
131•SerCe•8h ago•117 comments

Show HN: R3forth, a ColorForth-inspired language with a tiny VM

https://github.com/phreda4/r3
70•phreda4•12h ago•14 comments

Female Asian Elephant Calf Born at the Smithsonian National Zoo

https://www.si.edu/newsdesk/releases/female-asian-elephant-calf-born-smithsonians-national-zoo-an...
28•gmays•7h ago•10 comments

Learning from context is harder than we thought

https://hy.tencent.com/research/100025?langVersion=en
176•limoce•3d ago•96 comments

FORTH? Really!?

https://rescrv.net/w/2026/02/06/associative
63•rescrv•20h ago•22 comments

WebView performance significantly slower than PWA

https://issues.chromium.org/issues/40817676
31•denysonique•9h ago•6 comments
Open in hackernews

Unification (2018)

https://eli.thegreenplace.net/2018/unification/
78•asplake•5mo ago

Comments

primitivesuave•5mo ago
Brought back memories to over a decade ago with Mathematica. It's quite easy to pattern match simple expressions like:

``` expr = foo[bar[k], baz[V]]; expr /. foo[x_, baz[y_]] :> {x, y} ```

But in real-world use cases, this paradigm quickly exposes some unhandled edge cases, or cases where the evaluation becomes prohibitively expensive. Nowadays I use TypeScript, and this has ignited some curiosity into finding out if TS does anything to optimize for this in type inference.

asplake•5mo ago
That’s kinda what brought unification to my attention. For my own education I’m writing a compiler for a simple ML-style language. Enjoying Pierce’s Types and Programming Languages meanwhile.
cubefox•5mo ago
Where do you need full type unification rather only type pattern matching?
guerrilla•5mo ago
I think in dependently typed programming languages and theorem proves. As I understand it, even System F (like Haskell) benefits, no?
cubefox•5mo ago
I guess in System F, if a function f accepts a complex type A, and another function g returns a complex type B, both types could involve type variables. Then for the compiler to check whether the expression f(g) is valid, it (the compiler) needs to determine whether a unification of A and B is possible. Not sure though.
dunham•5mo ago
As I understand it, dependent type theory requires higher order unification, which is undecidable. So they typically use bidirectional type checking instead of Hindley Milner.

With bidirection type checking, I think it only needs the unification when solving inserted implicits. So a plain dependent type theory wouldn't need it, but once you add implicit parameters, you do need it. They usually use pattern unification, which solves a subset of higher order unification problems, for those unification problems.

housecarpenter•5mo ago
Consider the identity function f, which just takes an argument and returns it unchanged, and has the polymorphic type a -> a, where a is a type variable. What's the type of f(f)?

Obviously, since f(f) = f it should be a -> a as well. But to infer it without actually evaluating it, using the standard Hindley-Milner algorithm, we reason as follows: the two f's can have different specific types, so we introduce a new type variable b. The type of the first f will be a substitution instance of a -> a, the type of the second f will be a substitution instance of b -> b. We introduce a new type variable c for the return type, and solve the equation (a -> a) = ((b -> b) -> c), using unification. This gives us the substitution {a = (b -> b), c = (b -> b)}, and so we see that the return type c is b -> b.

But if we use pattern matching rather than unification, the variables in one of the two sides of the equation (a -> a) = ((b -> b) -> c) are effectively treated as constants referring to atomic types, not variables. Now if we treat the variables on the left side as constants, i.e. we treat a as a constant, we have to match b -> b to the constant a, which is impossible; the type a is atomic, the type b -> b isn't. If we treat the variables on the right side as constants, i.e. we treat b and c as constants, then we have to match a to both b -> b and c, and this means our substitution will have to make b -> b and c equal, which is impossible given that c is an atomic type and b -> b isn't.

moi2388•5mo ago
“ lowercase letter represents a constant (could be any kind of constant, like an integer or a string) An uppercase letter represents a variable”

I already disagree with this syntax.

brodo•5mo ago
That's the default way it has been done in Prolog since forever. If you have static typeing, like in Soufflé, you can get around it.
maweki•5mo ago
Datalog does not need/do unification for rule evaluation, as it is just matching variables to values in a single direction. Body literals are matched against the database and the substitutions are applied to the rest of the rule and the head.

Prolog does unification of the proof goal with the rule head. It's necessary there but not with datalog.

kevindamm•5mo ago
While bottom-up evaluation is the norm in datalog, it is not a requirement and there are datalog engines that evaluate top-down or all-at-once.

But I still agree with you about the capitalization. Some formats, like KIF, use a '?' prefix instead, and I've seen some HRF notations that mix the '?' prefix with non-KIF formatting (':-' operator and '.' terminator).

cubefox•5mo ago
It's also used in the theory of formal grammars, where terminal symbols (constants) are lower case, and non-terminal symbols (variables) are upper case: https://en.wikipedia.org/wiki/Formal_grammar#Introductory_ex...
moi2388•5mo ago
I did not know this, thanks
ux266478•5mo ago
Wait until you see Marseilles Prolog
piinbinary•5mo ago
Unification is the core of Algorithm W, aka Hindley–Milner type inference. It's at the core of the type inference algorithms for languages like Haskell, OCaml, and standard ML.
rurban•5mo ago
Why on earth would someone describe unification in python, when it's so much easier in lisp?
dragonwriter•5mo ago
Because they are trying to explain it to an audience that is more likely to be comfortable with Python?