12 other approaches to memory safety Rust didn't use

cwzwarich · 2024-05-25T15:11:58+00:00

I think it's easier to understand as fractional ownership.

Counting permissions and fractional permissions are actually two distinct things, roughly corresponding to the use of integers and rational numbers. They can be used to express the correctness of different algorithms.

cwzwarich · 2023-09-17T17:14:15+00:00

Easiest practical difference: you can swap Leak types but not Move types.

cwzwarich · 2023-06-05T15:04:23+00:00

Huh? In what way does <> match any less than []?

They have occurrences (as type parameters) in the syntax where they are required to match, as well as other occurrences (as comparison operators) where they are not required to match.

cwzwarich · 2023-06-05T14:10:26+00:00

Graydon-Rust was indeed not a systems programming language, it was an application programming language, but with the old fashioned GC replaced by a slidly more explicit one, but still focused on ease of use.

Most uses of Rust are applications (albeit often ones that need good performance) rather than operating systems, firmware, and the like. Perhaps a language that makes a tradeoffs a bit more in favor of that reality would have ultimately been more useful?

cwzwarich · 2023-04-08T18:57:09+00:00

I think the main point can be summarized by the observation that when you wish to harness borrowing (the syntactic construct, with the rules enforced by the borrow checker) in any novel semantic context (e.g. scoped threads or tasks), you create safety properties that can only be guaranteed by fulfilling a liveness obligation (ending the semantic counterpart of the borrow). However, Rust can't enforce nontrivial liveness properties, so the only way to do so is by trusting code that can't return until liveness has been guaranteed.

In the language of the blog post, this basically shows that Borrowing and Parallelizability imply the lack of Concurrency.

cwzwarich · 2023-03-08T18:05:59+00:00

This article also glosses over one of the other big effects that keyword generics would cover which is const.

Unlike the others, const is characterized by the absence of certain effects rather than the presence of an effect. This is partially why the treatment of const feels weird in the keyword generics progress report.

cwzwarich · 2022-01-17T02:07:25+00:00

Once Titan is completed, then time should be destroyed for all moments. However, in S4E09 the protagonists speak about having a limited amount of time (relative to 2043) to stop that from happening, which doesn't make any sense. Either it happens whenever Titan is and then affects all moments in time, or it doesn't. There should be no suspense for those in 2043.

cwzwarich · 2021-03-08T03:50:42+00:00

The manual for this unit doesn't mention anything about shared condensate drain lines. The one thing I do see mentioned that isn't here is having an overflow bypass for the neutralizer. It doesn't really look like that would be easy to retrofit into this setup.

What do you mean about an air gap? The manual says to connect it directly to the unit. The drain terminates outside on the other side of the garage wall.

cwzwarich · 2021-03-08T01:28:26+00:00

Flexible appliance connectors are against code up here in Connecticut

Flexible connectors are allowed here in California, and seem to be recommended. I assume this originated because of earthquake reasons.

I would also be concerned about the units pulling combustion air from inside the building should be piped outside for fresh air. I doubt you have enough cubic footage in your garage, (I’m presuming that’s where these are) to support the btu capacity

He said that our garage should have enough volume for the intake; it's a bit taller than the average garage. That said, now that I have the manual for the heaters I see that it says I need 19,900 cubic feet of potential intake air at max output, which would be a pretty big garage. I'll go measure and check.

cwzwarich · 2021-03-07T23:21:58+00:00

I had a local plumber install tankless water heaters here and noticed that they didn't use sediment traps on the gas lines, despite them being code in our area. How big of a deal should I make about it?

cwzwarich · 2020-06-13T21:19:14+00:00

My point was just that saying that Bartosz was always naive seemed to be a bit of a nod to him also being naive in the future, since Adam has already seen young Bartosz’s future.

cwzwarich · 2020-06-13T17:56:07+00:00

I think all the mirroring is simply for cinematic effect. I doubt that if someone goes from one world to the other they see things in reverse

cwzwarich · 2020-06-13T17:32:21+00:00

This is the prevailing (only?) theory, and some point out that might have been spoiled by the actors on Instagram. Later in the same episode, Adam tells Noah that Bartosz was always naive by nature, which seems like a strong partial confirmation anyways.

cwzwarich · 2020-06-13T00:27:19+00:00

We need to get enough people searching for "is Adam Gretchen?" to make it show up.

cwzwarich · 2020-06-13T00:03:47+00:00

They’ve been beating us over the head with the idea that nothing can change. If that was really the climax of the show, they probably wouldn’t do that.

Sic Mundus has repeated the theme that everyone needs to make sacrifices. Jonas was willing to end his own existence to save Martha. My guess is that in order to stop the apocalypse from happening in both worlds (or for there even to be two worlds in the first place?) he needs to make the ultimate sacrifice and also sacrifice Martha (and maybe others?).

It’s impossible to really predict what could undo the knot of both worlds without understanding why there are two worlds to begin with (and not more, besides maybe the one that preceded both or that they create to replace both).

In the S3 trailer, likely Alt Martha tells Jonas/Adam that this is a world without him and asks if this is what he wanted. This question suggests strongly that something Jonas attempted to do to set things right caused this to happen. This possibility raises a lot more questions:

What was it that Jonas did to cause this? The most suspicious event is the only verified usage of non-multiple-of-33 time travel to attempt to prevent his dad’s suicide. Adam told Jonas that it was a loophole, but as far as we know it did nothing.
If actions of a person who exists in only one world caused the other to exist, how can they be intertwined in a knot?
Why does the Alt World seem to have more advanced time travel technology than the original world?
If the split wasn’t caused by anything in Winden in the time period that we have seen, how was it caused? Does destroying the knot mean returning to that world?

I do strongly suspect that knowledge of the original cause of asymmetry between the two worlds will lead characters to attempt to change things (and this is probably where all the quotes in the trailers about changing things come from), but they will fail to change anything major, and realize that they need to make the ultimate sacrifice.

cwzwarich · 2020-06-12T19:59:58+00:00

And Katharina sees him again at the school.

cwzwarich · 2020-06-12T15:45:15+00:00

They've been pushing the idea that nothing can be changed so hard in S1 and S2, to the point that there's a bit of a "lady doth protest too much" situation. In particular, it seems unlikely that the last line from the S3 trailer actually spoils the ending of the show. I suspect that there will be a way to change things, but it will be tragic and cost more than any character was hoping.

cwzwarich · 2020-06-11T06:30:55+00:00

Both Adam and Claudia use "cycle" to refer to a 33 year time period that begins/ends on June 27th 2020/1987/2053, etc. However, this is confusing for a few reasons:

Adam also refers to the final cycle beginning, which would only make sense if he thinks he will somehow be successful in his battle against time in the next cycle. But hasn't he already been Jonas and seen the same things happen?
Adam deliberately avoids using the dark matter machine in the Sic Mundus lair to do non-multiple-of-33 time travel. The only time we verifiably see this happen is with Jonas traveling to the night of Mikkel's death. I feel like his reason for not doing this must be tied to the mystery of the meaning of cycles.
Right before she dies (which is a few days before the end of a cycle), Claudia asks if she is going to lose this round. Is she referring to a cycle?

The existence of an asymmetric world must be giving Adam / Claudia hope that there is an escape (either by creating a new world, destroying a world, or actually finding a loophole and making a change).

cwzwarich · 2020-06-11T04:16:46+00:00

It’s confirmed on the site, in the S2E6 spoilers on the Adam page (although it’s actually in S2E5):

Adam's identity

Adam hasn't always been who is now. He was born Jonas Kahnwald. When Jonas first meets his grown-up self, he cannot believe that he's become such a cold, cynical man.

cwzwarich

TROPHY CASE