Swift at Apple: Migrating the TrueType hinting interpreter

DDASD about 3 hours ago 35 commentsRead Article on swift.org

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Discussion (35 Comments)Read Original on HackerNews

AndriyKunitsyn•7 minutes ago

What's funny is from 2023 (I think), macOS just draws the UI unhinted. You have a 1080p display and you don't want to see the letters in the UI blurred to death? Tough luck, 1080p is incompatible with macOS, everybody needs "retina", and nobody cares that Windows and all Linux DEs look on 1080p just fine.

It looks like this hinter will be used only in rendering PDFs, because that's where they test the performance.

pjmlp•about 2 hours ago

During the State of Platform keynote, on the subject of Swift adoption across macOS, several examples were given, not only TrueType engine.

RIS is happening across all OS levels, if the keynote is to be believed.

DASD•about 2 hours ago

Curious the direction of Webkit as there was a nebulous mention of select portions being rewritten from C++ to Swift. And yet, the new ECMAScript module (ESM) loader for Safari 27 is implemented in C++ (https://webkit.org/blog/17967/news-from-wwdc26-webkit-in-saf...).

pjmlp•about 2 hours ago

No idea, maybe the private parts of the code, Safari isn't open source, or is coming later.

In any case I would have liked to have more info during the deep dive sessions.

As it is, Meet with Apple on security (a 5h long event) had much more information.

hirvi74•36 minutes ago

What does RIS stand for?

gyomu•35 minutes ago

Rewrite in Swift

willXare•14 minutes ago

So RIS is Apple’s version of RiiR, but with better fonts.

airstrike•about 1 hour ago

As much as I enjoyed Swift, one can only wonder what the world would look like if they had gone with Rust as their default language instead.

AceJohnny2•9 minutes ago

Rust doesn't have an ABI [1]. Swift needed one to be a useable application language:

https://faultlore.com/blah/swift-abi/ (written by a core Rust developer)

[1] apart from the basic/universal C one, which prevents exposing any useful Rust semantics over the interface

jadengeller•about 1 hour ago

Modern Swift borrows a lot from Rust! And it also has its own benefits, both ergonomic and also supporting eg generic in dynamic libraries

ecshafer•about 1 hour ago

Swift and Rust were developed at similar times. I think of them more as having similar influences than borrowing from each other.

est31•about 1 hour ago

Similar times and the Rust originator went on to work on Swift after it.

airstrike•about 1 hour ago

These days I mainly write Rust but I did write a semi complex iOS app and enjoyed Swift. I just didn't love how slow the type checker was and how it got lost. I recall having to break things into smaller bits to help the compiler, and there were some oddities about the language.

The gap between the two languages is quite small, it just makes me wish Apple was also all-in on Rust

DenisChetwynd•32 minutes ago

maybe so on the surface, but it remains quite massive underneath; these languages are fundamentally different and target entirely different use cases

vardump•about 1 hour ago

Does it borrow borrow checker?

saagarjha•about 2 hours ago

Interesting that this is published under the MIT, rather than Apple’s more favorite Apache 2, license

JumpCrisscross•about 2 hours ago

Why is it interesting?

drob518•about 2 hours ago

Presumably because MIT is even more permissive and it’s a change in Apple’s behavior.

favorited•17 minutes ago

Some corporations prefer Apache 2.0 for projects where they'll be accepting contributions, because it includes patent protection and retaliation clauses. In case like this, where source code is just being published for reference and contributions aren't accepted, those risks don't exist.

zdw•34 minutes ago

Given the age of TrueType, wouldn't nearly all patents be expired already?

Apache2's license I've heard described as mutually-assured-patent-destruction - if you use the code and make a patent claim, your rights to use the code go away.

So Apache2 offers little benefit here, and MIT may get it into more hands?

weinzierl•about 2 hours ago

Back in 2023 there was talks about Microsoft rewriting the font stuff in Rust for similar reasons Apple is now doing the Swift move.

I'm not sure what became of it and if it ever shipped. If anyone knows I'd be curious.

DASD•about 1 hour ago

Russinovitch (Azure's CTO/CISO) gave a speech at RustConf 2025 and mentions it(DirectWriteCore) took 2 engineers 6 months resulting in 154K LOC and 5-15 percent performance increase for font shaping. https://www.youtube.com/watch?v=uDtMuS7BExE&list=PL2b0df3jKK...

mrpippy•about 2 hours ago

The author discussed this a bit on Mastodon as well:

https://xoxo.zone/@numist/116716469017975106

numist•about 1 hour ago

I'm also here :)

raphlinus•about 1 hour ago

Welcome to the club of doing high performance text in a memory safe language!

LoganDark•about 2 hours ago

I'm surprised the code has visible LLM smells. Though, I shouldn't be surprised. I hope the important bits are still human-controlled (and the same for Apple's many operating systems that absolutely deserve to remain stable and understood).

airspeedswift•about 1 hour ago

I assure you, every inch of the interpreter code has been stared at by humans, a lot. TBH even the assembly generated by it has.

dgellow•about 2 hours ago

From what I got Apple is using claude code A LOT internally

Cassell•about 1 hour ago

It would be interesting to see their internal guidance on LLM use. It’s a massive amount of new power that has to be wielded carefully. That kind of guidance might mean the survival or downfall of some big corps in the next few years.

wahnfrieden•about 1 hour ago

Yes they are using Claude Code - not the Xcode agents.

It worries me. I hope Codex adoption picks up there.

troupo•about 2 hours ago

I think these are the types of things Apple should've focused on instead of half-heartedly barging ahead with SwiftUI and breaking the language in the process

saagarjha•about 2 hours ago

I mean they’re doing both

wg0•44 minutes ago

No mention of AI? Hand written code?

numist•9 minutes ago

There's mention at the end. The models (and Swift itself!) have evolved a lot since this project started, so the early code is largely hand-rolled and the later changes were mostly authored by centaurs (to steal a term from chess).

But I personally reviewed every line that shipped and was absolutely insufferable about testing.