Aaron Turon

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aturon.log: listening and trust, part 3

In this third post in the listening and trust series, I’m going to talk through one of the most intense discussions the Rust community has had: the module system changes that were part of last year’s ergonomics initiative.

The saga, summarized

The modules saga demonstrates both payoffs and pathologies of the RFC process, playing out over a dozen different threads reaching 1,400+ comments in total.

It was, in the end, a success – at least as gauged by the collective enthusiasm for the final result, compared to the starting point. Yet it left wounds that have not entirely healed, which is part of why I want to talk about it here.

The 2017 roadmap focused on productivity and learnability, and the Lang Team took a look across the language for areas of improvement. Modules were a well-known stumbling block for many users, though many others (including most of the Lang Team) found it simple and easy to grasp. So the first order of business was working to understand what people found confusing or difficult about modules, which led to a couple of initial threads:

These early threads produced some important insights into how different people experienced the module system. They also highlighted the level of controversy to expect around any discussion involving such a fundamental change, even one that was far from a complete proposal.

A few months later, a subset of the Lang Team and some others spent a few hundred person-hours delving into both the problem and solution space. We worked through about a dozen different designs before finally reaching a mix of ideas that seemed plausible enough to present to the community. I did so in an initial blog post, which also took a stab at a “comprehensive” analysis of the problems. The post generated an enormous amount of discussion, and a week later I closed its thread in favor of a new one with a revised proposal, which @withoutboats revised further. There were also a handful of other threads with additional proposals, or that drilled into specific aspects in greater detail.

One of the problems the original proposal called out was “path confusion”. The revised proposal summarized some of the feedback as saying:

Many on the thread cited this as the core problematic issue with the module system; I’ve collected some data about confusion around Rust modules which also supports that to a degree.

and suggested an approach that gave more weight to solving those problems.

After reaching what seemed to be a rough consensus on the internals thread around the third design, @withoutboats wrote up a complete proposal as an initial RFC. A similar story played out, with that initial RFC garnering quite a bit of feedback in multiple directions, and ultimately being closed in favor a second, and then a third (and final) RFC.

The RFC that was ultimately accepted bears almost no resemblance to any of the initial design sketches. It ultimately took the “path confusion” issue as the problem to address, and oriented the design more completely around that issue than any of the earlier proposals did. (Discussion of some aspects of the design is ongoing; there will soon be a 2018 Edition Preview where we’ll be looking for further feedback.)

With that basic background in place, I want to examine some of the social dynamics that played out along the way, from the context of listening and trust.

Momentum, urgency, and fatigue

I think that, collectively, we all remember the modules discussion as intense. But it’s interesting to dig into the ways it was intense.

In my memory, the discussion was heated. But it turns out that memory was faulty: when I went back and re-read all of these threads, I was shocked by the relative lack of heat! Granted, there were a few outlier comments, but I came away convinced that the sense of intensity was not primarily about the discussion being charged.

What I noticed, instead, is a recurring mention of the length and velocity of the comment threads involved. Threads were accruing hundreds of comments per week, and there was a sense of high stakes (the Lang Team is considering changing the module system!), so many people felt compelled to get involved, at least at the beginning. And the only way to do so was to participate in those threads, thus compounding the effect.

While the modules discussion was an extreme case, the issue of comment thread velocity is a familiar one in Rust. A high velocity thread often seems heated and “controversial”, even if the discussion is respectful and chock full of insights. I think this is part of why feelings about the modules discussion are so complex, and why it seems an exemplar of both the best and the worst of the RFC process.

I personally don’t see high comment velocity as a root problem, but an issue that relates to deeper dynamics:

  • Momentum. A comment thread has a kind of “momentum” of sentiment that can be hard to shift, and also hard to gauge as the thread gets long. If an RFC has an initial batch of negative (or positive) comments, it can be difficult to recover, in part because these are the first sentiments everyone sees.

  • Urgency. Because comment threads are a major input into the decision-making process, there’s a sense of urgency to participate and keep the discussion “on course” from your personal perspective. This urgency is compounded when a thread is fast-moving or lengthy, or when a proposal originates from a team member (and thus is reasonably seen as having a higher chance of landing).

  • Fatigue. Many people participate early on in an RFC thread, only to ultimately step away because the thread has too much traffic to keep up with or influence. There’s also sometimes a feeling of a topic getting discussed “to death”; many felt that way toward the end of the modules saga.

Some of these social dynamics are inevitable with a project as large and open as Rust. But the net effect is a bit like the one I talked about in the first post in the series: the sense that you need to be “in the room when it happens”, and that it takes a lot of time and stamina to do so. In this case it’s not about the moment of decision per se, but rather the struggle to set the direction of the comment thread. I often hear from people who are intimidated by the RFC process precisely because of the huge comment threads. Not to mention, of course, the enormous amount of work needed to fully participate in those threads.

These issues are particularly pronounced for early-stage discussions. “Brainstorming” can get overwhelmed either by a deluge of ideas, or (much worse) strong attempts to kill an idea before it has any chance to take root.

But I don’t think comments themselves are the problem; the whole process is, after all, a request for comments! I think the problematic dynamics stem instead from two core process problems:

  • A lack of clarity about the “stage” of any given discussion. A thread brainstorming on a new way to approach Ok-wrapping should not need to recapitulate fundamental disagreements on whether Ok-wrapping is desirable.

  • Too much emphasis on “the thread”, rather than on standalone artifacts. We don’t have a good process or culture around reflecting the discussion into the RFC itself, and while we do sometimes make “summary comments” to help manage discussion, they tend to get lost in the noise. The RFC thread takes on a primary, high stakes role instead.

I believe that if we adjust our process to address these two issues head-on, it will go far in further eliminating the requirement to be “in the room” at the right time, and the negative effects that come with it.

Wielding power; changing minds

In my last post, I mentioned a sentiment I’ve often seen, one sometimes made in reference to the modules discussion:

Luckily enough of us yelled to stop the terrifying original proposal from happening; the moment we stop speaking up, Those People will start pushing in that direction again.

I understand where this sentiment comes from; the RFC that landed indeed bore little resemblance to the starting point, due in part to pushback. But there are two distinct ways to understand why RFCs change, and what it means:

  • Wielding power. There were some particular aspects of the early modules proposals, like removing the need for mod statements, that garnered a strong negative reaction from a number of people. It took a lot of iterations, but ultimately that part of the proposal was dropped. It would be reasonable to see this as part of the community asserting itself, being loud enough about strong preferences to make it clear that certain changes would be intolerable. The result could be a capitulation, or compromise, in which the original proposers relent and “take what they can get”.

  • Changing minds. On the other hand, a number of folks who were positive about the original proposal were even more positive about the final one. For them, the final proposal wasn’t a compromise at all, but rather the best option.

I’m personally in the latter camp: I’m much happier with the RFC that landed than with the original proposal, and I wrote both of them! But I think both of the above elements were at play. Let me explain.

It was not until very late in the process that we stopped proposing to drop mod statements, and there’s no question that, had it not been for the persistence of a few people, it wouldn’t’ve happened. Power was, indeed, wielded. But the reason for changing the proposal wasn’t simply “well, we can’t get this through, so let’s scale back”. Rather, those lengthy comment threads and disagreements forced us all to dig deeper into the problem space. And we eventually learned that our original analysis of the core problem was just wrong, that the “path confusion” issue that I initially treated as secondary was actually the problem.

This is part of why I don’t want to put blame on comments themselves. Our willingness to dig deep and long to find new insights and more nuanced designs is a big part of what’s made Rust the language it is, and why I love working on it so much. Sometimes talking something “to death” is exactly what’s needed to uncover the right set of ideas.

I don’t think it’s the job of the Rust Teams to seek a compromise solution, which is a recipe for design by committee; we need a strong, coherent final design. I think we should be convinced that the solution is within striking distance of the best for our plural community. And thus the role of the RFC process is precisely to facilitate deep digging, to explore ideas, tradeoffs and constraints and look for the option that genuinely seems best.

Lived experience; active listening

A final dynamic that showed up throughout the modules discussion: reports of “lived experience”.

Going back to mod statements, several people talked about the role they play in their personal workflow, whether due to their IDE, their lack of IDE, their habits with respect to temporary files, or even the latency of their file system.

No one can be wrong about their own lived experience. And lived experience can bring issues to life in a way that pure empathy and speculation can’t. Thus, a big benefit of the RFC process is the crowdsourcing of lived experiences that it provides.

Unsurprisingly, one’s own lived experience always looms large. But our job in building a language is to account for the experience it provides for a large and diverse set of current and future users, many of whom are not well-represented on RFC threads. Thus accounts of lived experiences are data points, at best proxies for the experiences of similar users, but ultimately information that needs to be weighed in a global design space.

The work of an RFC thread is in part to employ active listening to turn lived experience into design constraints. In cartoon form this might look as follows:

  • A: “I am against this RFC.”
  • B: Why?
  • A: “I don’t want to get rid of mod statements, I think they’re very important.”
  • B: Can you say more about what role they play for you?
  • A: “They make it easy to temporarily remove modules while refactoring.”
  • B: OK, so you have as a design constraint that workflows for refactoring should remain ergonomic?
  • A: “Yes.”

The last post talked about the feelings that inevitably come into play in any discussion you care about. They’re strongest when they touch on lived experience. They should not be hidden away, but part of the emotional labor of the RFC process is to recognizing such feelings as emerging from our personal experience, and working introspectively to dig out the actual constraints that represents – and then to weigh those against the constraints of other present and future Rust users. We can help each other to do so, as in the cartoonish dialogue above. But even better if we can each do some of that work privately first, and come to the thread not with a flat “I am against this RFC” but rather “I’m concerned about refactoring workflows; here’s what my personal one looks like…”


Last week a few folks from the Rust Core Team got to spend a few hours talking about the RFC process in person – something we’ve done many times before, but that led in a more conclusive direction this time around. Niko is writing up some of the ideas, which are partly aimed at the problems raised in this post.

Ultimately, though, we can’t solely rely on process improvements; we need to do the work of reflecting on, writing down, and improving our design culture as well. I plan at least one more post in the Listening and Trust series, and then on to other, broader topics.