proposal-ptc-syntax
WebKit
proposal-ptc-syntax | WebKit | |
---|---|---|
8 | 151 | |
165 | 7,456 | |
0.6% | 1.7% | |
0.0 | 10.0 | |
almost 8 years ago | 5 days ago | |
HTML | ||
- | - |
Stars - the number of stars that a project has on GitHub. Growth - month over month growth in stars.
Activity is a relative number indicating how actively a project is being developed. Recent commits have higher weight than older ones.
For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
proposal-ptc-syntax
-
Time, Space and Complexity
The proposal of "syntactic tail calls" to provide an explicit syntax for tail calls, co-championed by committee members from Mozilla (responsible for SpiderMonkey, the engine of Firefox) and Microsoft, was a response to these concerns. However, this proposal is now listed among the TC39's inactive proposals, possibly due to diminished interest, which may stem from the infrequent use of tail recursive functions in JavaScript.
-
Bun, JavaScript, and TCO
This is not actually about Tail Call Optimisation, which is more flexible and optional matter of optimisation, but about Proper Tail Calls, which are actually part of the ECMAScript 6 specification (over implementer objections)—in strict mode, calls in tail position must not create additional stack frames. This is the last piece of ECMAScript 6 that most engines haven’t implemented, because it’s rather controversial: it actually causes some performance problems, and makes debugging harder, and may have security issues (in 2016, Mozilla declared it impossible to implement across realm boundaries due to their security model).
https://github.com/tc39/proposal-ptc-syntax has a lot of useful information about it all, and a proposal to make it explicit in syntax, such as with `return continue …`.
(Fun terminology problems here. The term TCO is commonly used for PTC, and PTC is very close to being a subset of TCO, but the mandatory stack frame elision which ruins debugging feels to me like it falls outside of TCO. In various situations, debuggers will mark things like “stack frame omitted” when they’ve optimised one out of existence, but you can generally compile things differently, or something like that, to prevent this. But with PTC, it feels like the engine is kinda not even allowed to know that a stack frames may be absent. So I say PTC and TCO are a little distinct, though PTC is mostly just a subset of TCO. Reminds me of the terminology of tree-shaking versus dead code removal—where the former is essentially a subset of the latter, but that the effects are just slightly different, though I’d say it’s more slight in that case than this.)
-
Show HN: We are trying to (finally) get tail-calls into the WebAssembly standard
4. Proposed something else [ https://github.com/tc39/proposal-ptc-syntax ]
While apple is against Syntactic tail calls, they’re mainly just opposed to versions of it that would remove/unrequire the tail-call optimisation they already do: https://github.com/tc39/ecma262/issues/535
For the version of it that is backwards compatible, they wouldn’t need to do anything other than recognise it as valid syntax. Their main concern is that it "could add confusion with very little benefit."
-
What happened to proper tail calls in JavaScript? (2021)
The spec for STC has a critique of PTC:
- performance
- developer tools
- Error.stack
- cross-realm tail calls
- developer intent
See: https://github.com/tc39/proposal-ptc-syntax#issues-with-ptc
Apple's 2016 response as to why they won't implement STC is here: https://github.com/tc39/ecma262/issues/535
- STC is part of the spec and will take too long to change.
- Now that they've implemented support for PTC, they don't want to regress web pages that rely on it.
- They don't want to discourage vendors from implementing PTC by agreeing to STC.
- They don't want to introduce confusion.
Some of these arguments about confusion and delays seem wrong hindsight, since on every point things would have been better if they'd just agreed to the compromise of STC.
- It would have been part of the spec years ago
- STC would have had a clear way for web pages to know when tail calls could be relied on (and PTC would have been optional)
- Other vendors didn't implement PTC in any case, despite no agreement on STC
- There's even more confusion as things are now
-
@lrvick bought the expired domain name for the 'foreach' NPM package maintainer. He now controls the package which 2.2m packages depend on.
You can see a direct example of this with Proper Tail Calls (PTC). It was added to the ECMAScript spec in 2015 as part of es6, but as of today - 7 years later - only Safari has shipped it*. As a result it is effectively not a thing in JavaScript, and the followup proposal meant to address issues with PTC ("Syntactic Tail Calls") has been basically ignored because PTC is already in the spec.
-
Node.js 14 is over 20x faster than Python3.8 for fib(n)
V8 implemented tail call optimization in the past, and the V8 team backed the TC39 proposal for syntactic tail calls (where you'd write return continue func() to make the use of TCO explicit). In Node 6 and 7 we could use them with the flag --harmony-tailcalls. The feature was removed from Node 8 after that proposal didn't go anywhere, but it's interesting, and shows some interest.
WebKit
-
GPU Compute in the Browser at the Speed of Native: WebGPU Marching Cubes
Multiple engineers are working on adding it back: https://github.com/WebKit/WebKit/pulls?q=is%3Apr+is%3Aclosed...
-
HTML Streaming and DOM Diffing Algorithm
Since 2023 Chrome announced the View Transition API, and it looks like Safari is also going to support it soon.
-
Towards memory safety with ownership checks for C
One heap per type.
Here’s an allocator optimized for that use case.
https://github.com/WebKit/WebKit/blob/main/Source/bmalloc/li...
-
Bun, JavaScript, and TCO
To use this in Bun, you’d have to start Bun with the environment variable “BUN_JSC_useDollarVM=1” and then $vm.createBuiltin(mySourceCodeString)
When using this intrinsic, if any of the arguments are incorrect or it cannot otherwise enable it, the entire process will probably crash. In debug builds of JSC it will have a nicer assertion failure but that is not enabled in release builds
Example code: https://github.com/WebKit/WebKit/blob/17351231b4dedb62d81721...
also happy to answer any questions about Bun
-
Show HN: Rem: Remember Everything (open source)
Ah, good, let me introduce you to the wonderful world of the Chrome Devtools Protocol! (fka Chrome Remote Debugging Protocol)
I love this API for almost everything browser related. I built my RBI product atop this (BrowserBox: https://dosyago.com), and I think it's a drastically underrated API.
Also, it works out of the box in Edge, Brave, Chromium, and many parts of CRDP are supported by Firefox and Safari^1
1: See for example: https://github.com/WebKit/webkit/tree/main/Source/JavaScript...
- WebGPU now available for testing in Safari Technology Preview
-
Disabling iOS Personalized Ads tells kernel to kill daemon every 3 seconds
No, it's unrelated.
https://github.com/WebKit/WebKit/commit/064df1a9f395f8c6e32c...
- Apple's Safari browser is still vulnerable to Spectre attacks
-
Replacing WebRTC: real-time latency with WebTransport and WebCodecs
It's being worked on now: https://github.com/WebKit/WebKit/pull/17320
-
iLeakage: Browser-Based Timerless Speculative Execution Attacks on Apple Devices
It is different. The cross-site navigation flag is a couple of years old. It was enabled by default for iOS in November 2018 for example https://github.com/WebKit/WebKit/commit/e191fc8c412850cb9fd0...
What are some alternatives?
ecma262 - Status, process, and documents for ECMA-262
chromium - The official GitHub mirror of the Chromium source
uwm-masters-thesis - My thesis for my Master's in Computer Science degree from the University of Wisconsin - Milwaukee.
otter-browser - Otter Browser aims to recreate the best aspects of the classic Opera (12.x) UI using Qt5
Elixir - Elixir is a dynamic, functional language for building scalable and maintainable applications
cname-trackers - This repository contains a list of popular CNAME trackers
constant-time - Constant-time WebAssembly
fingerprintjs - Browser fingerprinting library. Accuracy of this version is 40-60%, accuracy of the commercial Fingerprint Identification is 99.5%. V4 of this library is BSL licensed.
foreach - Foreach component + npm package
gecko-dev - Read-only Git mirror of the Mercurial gecko repositories at https://hg.mozilla.org. How to contribute: https://firefox-source-docs.mozilla.org/contributing/contribution_quickref.html
rr - Record and Replay Framework
uBlock-Safari - uBlock Origin - An efficient blocker for Chromium, Firefox, and Safari. Fast and lean.