Stream: wg-traits

Topic: weeky meeting 2019-03-11


nikomatsakis (Mar 11 2019 at 17:57, on Zulip):

Hi @WG-traits =) Sync meeting in a few minutes

scalexm (Mar 11 2019 at 18:00, on Zulip):

Was there an hour shift somewhere in the world?

scalexm (Mar 11 2019 at 18:00, on Zulip):

Usually it’s 8pm my time I think

Sunjay Varma (Mar 11 2019 at 18:01, on Zulip):

Yes

Sunjay Varma (Mar 11 2019 at 18:01, on Zulip):

DST began yesterday

Sunjay Varma (Mar 11 2019 at 18:02, on Zulip):

So we lost an hour

nikomatsakis (Mar 11 2019 at 18:03, on Zulip):

This will last for a few weeks

nikomatsakis (Mar 11 2019 at 18:03, on Zulip):

I'm trying to remember

nikomatsakis (Mar 11 2019 at 18:04, on Zulip):

Did we have a paper or anything like that where we are kind of tracking things?

tmandry (Mar 11 2019 at 18:04, on Zulip):

at one time we did

nikomatsakis (Mar 11 2019 at 18:04, on Zulip):

seems like we don't have the condensed version I am thinking of

tmandry (Mar 11 2019 at 18:04, on Zulip):

this doc

nikomatsakis (Mar 11 2019 at 18:04, on Zulip):

here are the minutes from our previous meeting though

nikomatsakis (Mar 11 2019 at 18:05, on Zulip):

yeah, maybe we can adapt that paper doc

nikomatsakis (Mar 11 2019 at 18:05, on Zulip):

I'd basically like to be evolving so that we track our 'active projects' and current goals within that context

nikomatsakis (Mar 11 2019 at 18:06, on Zulip):

well anyway, plans for the coming week were:

nikomatsakis (Mar 11 2019 at 18:06, on Zulip):
nikomatsakis (Mar 11 2019 at 18:07, on Zulip):

In terms of the first point: I did yet more investigation. I feel like I could walk through the current state of normalization but haven't had time to schedule an actual call.

nikomatsakis (Mar 11 2019 at 18:07, on Zulip):

I am however feeling kind of curious by now if lazy norm is truly a blocker for const generics as has been claimed

nikomatsakis (Mar 11 2019 at 18:08, on Zulip):

One thing that is a problem is that, the way the code presently works, there are some steps we are not taking precisely to avoid cycles

nikomatsakis (Mar 11 2019 at 18:08, on Zulip):

so it makes hard to observe the cycle

nikomatsakis (Mar 11 2019 at 18:08, on Zulip):

since it does't occur :)

nikomatsakis (Mar 11 2019 at 18:08, on Zulip):

so I was thinking about trying to port back some commits from a PR by @eddyb so I could observe the problem first hand

nikomatsakis (Mar 11 2019 at 18:08, on Zulip):

I am interested in potentially collaborating with someone on this instead

nikomatsakis (Mar 11 2019 at 18:09, on Zulip):

Maybe that would be someone here at this meeting, or maybe worth putting out a bit of a call -- basically looking for someone to work with me on this investiation, doing some coding, syncing up semi-regularly

nikomatsakis (Mar 11 2019 at 18:10, on Zulip):

(Specifically what would be involved at this point is modifying the generics_of and predicates_of implementations for anonymous constants; it will require a bit of experimentation)

nikomatsakis (Mar 11 2019 at 18:10, on Zulip):

Don't everybody volunteer at once :stuck_out_tongue_wink:

nikomatsakis (Mar 11 2019 at 18:11, on Zulip):

Anyway it might just be you + me @tmandry :)

nikomatsakis (Mar 11 2019 at 18:11, on Zulip):

OK, well, let's move on. I'll come back to that point.

nikomatsakis (Mar 11 2019 at 18:11, on Zulip):

Explore the use cases for GATs (aturon, centril)

tmandry (Mar 11 2019 at 18:11, on Zulip):

lol, I was thinking I might have bandwidth for it but not sure when yet

nikomatsakis (Mar 11 2019 at 18:11, on Zulip):

I believe this happened, right @centril / @Aaron Turon? Over in this topic, and I think there is some form of document that I've failed to read

nikomatsakis (Mar 11 2019 at 18:14, on Zulip):

Here is a link to the document, which is a dropbox paper

nikomatsakis (Mar 11 2019 at 18:14, on Zulip):

I'm not sure the next steps here

nikomatsakis (Mar 11 2019 at 18:15, on Zulip):

I think it's probably to do some kind of review of these use cases, I thikn @scalexm did a bit of that already which is great

nikomatsakis (Mar 11 2019 at 18:15, on Zulip):

I guess I'll make a "work item" for myself at least on that, to do the review

nikomatsakis (Mar 11 2019 at 18:15, on Zulip):

Discuss RLS 2.0 type checker and contemplate how to integrate chalk
into it (nikomatsakis, scalexm)

nikomatsakis (Mar 11 2019 at 18:16, on Zulip):

So we had this meeting, and there was a plan to do another talk this week to cover some of how the Lark type checker worked

nikomatsakis (Mar 11 2019 at 18:16, on Zulip):

it occurs to me that I never scheduled this call :)

nikomatsakis (Mar 11 2019 at 18:17, on Zulip):

There is video available of the previous one

nikomatsakis (Mar 11 2019 at 18:17, on Zulip):

So I guess scheduling another chat is good here, though I think that beyond Lark we should also start talking about (and probably doing some hacking!) around the chalk integration question.

nikomatsakis (Mar 11 2019 at 18:18, on Zulip):

@scalexm how much time / interest do you have in hacking here

nikomatsakis (Mar 11 2019 at 18:18, on Zulip):

I'm trying to think what would be a good first PR

nikomatsakis (Mar 11 2019 at 18:18, on Zulip):

maybe trying to replicate something like what the rustc integration currently does?

nikomatsakis (Mar 11 2019 at 18:18, on Zulip):

i.e., to start by not sharing definition of types etc

scalexm (Mar 11 2019 at 18:19, on Zulip):

I definitely have a lot of interest in this, don’t know yet about time for hacking

nikomatsakis (Mar 11 2019 at 18:19, on Zulip):

or would it be better to start by trying to port to some common foundation

nikomatsakis (Mar 11 2019 at 18:19, on Zulip):

I'm guessing it would be better to start integrating chalk-engine

nikomatsakis (Mar 11 2019 at 18:19, on Zulip):

but with liberal use of panic! where needed

scalexm (Mar 11 2019 at 18:19, on Zulip):

I’m not sure about trying to replicate the what rustc does

scalexm (Mar 11 2019 at 18:19, on Zulip):

It seems like a lot of complex code duplicated

nikomatsakis (Mar 11 2019 at 18:20, on Zulip):

yeah

nikomatsakis (Mar 11 2019 at 18:20, on Zulip):

hmm

nikomatsakis (Mar 11 2019 at 18:20, on Zulip):

well we know we want to share the lowering code right

scalexm (Mar 11 2019 at 18:20, on Zulip):

Yes

nikomatsakis (Mar 11 2019 at 18:20, on Zulip):

maybe the thing to do is to schedule some time to try and sketch out what that means

nikomatsakis (Mar 11 2019 at 18:20, on Zulip):

i.e., I would be game to try and put one or two hours into reviewing what it might look like

nikomatsakis (Mar 11 2019 at 18:20, on Zulip):

and formulate a kind of roadmap / plan

nikomatsakis (Mar 11 2019 at 18:21, on Zulip):

any better ideas? :)

nikomatsakis (Mar 11 2019 at 18:21, on Zulip):

why don't we do this -- I will do an open call and spend some time on it. Anyone who wants can join, if just to "chat along"

scalexm (Mar 11 2019 at 18:22, on Zulip):

That sounds good

nikomatsakis (Mar 11 2019 at 18:22, on Zulip):

/me wants to do some coding dang it

scalexm (Mar 11 2019 at 18:22, on Zulip):

If we settle on something regarding sharing code, I’d be game for trying to hack a bit on that part

nikomatsakis (Mar 11 2019 at 18:22, on Zulip):

ok, sounds good

nikomatsakis (Mar 11 2019 at 18:22, on Zulip):

@Florian Diebold may also be interested

nikomatsakis (Mar 11 2019 at 18:23, on Zulip):

maybe we'll do that in place of the Lark review, although I still want to do that. I wouldn't mind pushing that till next week since I didn't schedule anything yet and I sort of want some time to prep

nikomatsakis (Mar 11 2019 at 18:23, on Zulip):

The next two items:

Did not happen.

nikomatsakis (Mar 11 2019 at 18:23, on Zulip):

However, @Alexander Regueiro and I have been talking about the "associated type bounds", so maybe we should add that as a work item

nikomatsakis (Mar 11 2019 at 18:23, on Zulip):

@Alexander Regueiro do you happen to be around?

centril (Mar 11 2019 at 18:23, on Zulip):

@nikomatsakis I'm going to work on let_chains a bit this week; If I have time over I'll work incrementally towards generic closures and for<T: Debug>

centril (Mar 11 2019 at 18:24, on Zulip):

(as RFCs, several... like 4 of them maybe)

nikomatsakis (Mar 11 2019 at 18:24, on Zulip):

@centril maybe say a bit more about what you have planned when you say "work incrementally towards" -- an RFC?

nikomatsakis (Mar 11 2019 at 18:24, on Zulip):

@centril I have a question. If I were to create a repository for the traits WG, which I've been meaning to do forever

nikomatsakis (Mar 11 2019 at 18:24, on Zulip):

how would you feel about posting some of those draft RFCs to the repo?

nikomatsakis (Mar 11 2019 at 18:24, on Zulip):

I'd enjoy being able to skim over them at my liesure

nikomatsakis (Mar 11 2019 at 18:25, on Zulip):

and I'd like to have a place to consolidate some of this planning etc

centril (Mar 11 2019 at 18:25, on Zulip):

@nikomatsakis sure, why not... I elaborated in https://rust-lang.zulipchat.com/#narrow/stream/144729-t-compiler.2Fwg-traits/topic/Generic.20bounds.20.26.20closures

nikomatsakis (Mar 11 2019 at 18:25, on Zulip):

I'd like to move generally towards a model of rfcs as "collaborative docs" that a working group si working on

centril (Mar 11 2019 at 18:25, on Zulip):

:+1:

nikomatsakis (Mar 11 2019 at 18:25, on Zulip):

ok, cool, i'll take a look

nikomatsakis (Mar 11 2019 at 18:26, on Zulip):

ok, so that's another work item to list

nikomatsakis (Mar 11 2019 at 18:26, on Zulip):

As far as "associated type bounds", I'll just put down "further progress" for now and mention @Alexander Regueiro =)

nikomatsakis (Mar 11 2019 at 18:27, on Zulip):

(I think I mentioned this before, i've been using :point_up: to help myself find key comments when making minutes later =)

centril (Mar 11 2019 at 18:27, on Zulip):

I make no promises of actually having a ready RFC for for<'a: 'b> this week tho =P let_chains may or may not take a bunch of time

nikomatsakis (Mar 11 2019 at 18:27, on Zulip):

ok, sound good, anybody got anything else to bring up?

nikomatsakis (Mar 11 2019 at 18:27, on Zulip):

I make no promises of actually having a ready RFC for for<'a: 'b> this week tho =P let_chains may or may not take a bunch of time

no hurry, I think the actual work item woudl be to upload drafts to a working group repo :)

nikomatsakis (Mar 11 2019 at 18:27, on Zulip):

and for me to create said repo, perhaps

tmandry (Mar 11 2019 at 18:27, on Zulip):

minor point about creating a traits repo: I can watch the repo without getting notifications for everything in t-compiler repo

nikomatsakis (Mar 11 2019 at 18:27, on Zulip):

sounds like a "point in favor"?

tmandry (Mar 11 2019 at 18:28, on Zulip):

indeed

centril (Mar 11 2019 at 18:28, on Zulip):

@nikomatsakis I meant the draft -- I make no promises wrt. that ^,-

nikomatsakis (Mar 11 2019 at 18:28, on Zulip):

ok yep

nikomatsakis (Mar 11 2019 at 18:28, on Zulip):

I meant the draft -- I make no promises wrt. that ^,-

I know, my point was, no worries :) nobody is asking for a promise :)

centril (Mar 11 2019 at 18:28, on Zulip):

:P

nikomatsakis (Mar 11 2019 at 18:28, on Zulip):

you do a ton :)

nikomatsakis (Mar 11 2019 at 18:28, on Zulip):

OK, cool, meeting adjourned then. :)

centril (Mar 11 2019 at 18:29, on Zulip):

that was quick :rabbit:

nikomatsakis (Mar 11 2019 at 18:30, on Zulip):

/me shoots for 30 minute meetings

nikomatsakis (Mar 11 2019 at 19:49, on Zulip):

Just wrote up a quick write-up from the meeting. These are my collected "next steps" from our conversation:

tmandry (Mar 11 2019 at 19:54, on Zulip):

@nikomatsakis so does the generics_of thing take the place of the call you had mentioned about normalization today + lazy norm?

nikomatsakis (Mar 11 2019 at 19:54, on Zulip):

probably, yes. I could definitely stilld o that

nikomatsakis (Mar 11 2019 at 19:54, on Zulip):

but I still dont' quite have all the "dots together"

nikomatsakis (Mar 11 2019 at 19:55, on Zulip):

i.e., I can talk about how system works, but I can't yet explain what the problem is that @eddyb was encountering and if I see an easy fix

nikomatsakis (Mar 11 2019 at 19:55, on Zulip):

maybe I can get @eddyb to listen to the talk and they may have some insights :)

Alexander Regueiro (Mar 11 2019 at 20:42, on Zulip):

@nikomatsakis sorry, bad time for me again this Monday. But yes, ATB well along the way.

Alexander Regueiro (Mar 11 2019 at 20:42, on Zulip):

Have we decided yet if lazy normalisation is definitely a blocker for fixing type alias bounds btw?

Alexander Regueiro (Mar 11 2019 at 20:46, on Zulip):

Also, what’s the progress on Chalk integration and lifetimes?

Last update: Nov 12 2019 at 17:05UTC