This article is part of the “Meta Advent 2019” series. I’ve committed to writing a new blog post here every day until Christmas.

A while ago I wrote an article, where I made the case Ruby seems to have lost its way. I thought I had exhausted the topic, but a few of the recent developments around the Ruby 2.7’s development lead me to revisit it.

Ruby 2.7 has become infamous at this point for several highly controversial changes that were either quickly revised or removed. A classic tell-tale of good project management and a clear vision for the future, right?

Let’s examine a few of those ill-fated changes in no particular order…

Flip-flops Forever

Remember how the flip-flop operator (..) was finally deprecated in Ruby 2.6 after years of discussions? Well, it just got (quietly) reinstated.

I find it really amusing how this went down - 3 (!!!) people complained about the deprecation and Matz quickly responded with:

I hear the negative feedback from the community. OK, I give up. The warning should be removed.

– Matz

There are numerous other instances where he ignored the complaints of way more people. Go figure. As usual, there was no real discussion on the ticket - just a decision. Not to mention that no one even thought to try to solicit more community feedback on the subject. I learned about the removal of the deprecation when someone posted this on Twitter…

None of this is new, in Ruby-land it’s business as usual. It’s just becoming progressively more frustrating for me.

Numbered Parameters Revisited

Remember the highly controversial numbered block parameter syntax?

# now
[1, 2, 3].each { |i| puts i }
(1..10).map { |i| i * 3 }
(1..9).each_slice(3).map { |x, y, z| x + y + z }

# Ruby 2.7
[1, 2, 3].each { puts @1 }
(1..10).map { @1 * 3 }
(1..9).each_slice(3).map { @1 + @2 + @3 }

After quite the backlash this syntax was revised to something more reasonable:

[1, 2, 3].each { puts _1 }
(1..10).map { _1 * 3 }
(1..9).each_slice(3).map { _1 + _2 + _3 }

A great success, right? Matz made a couple of interesting comments on this mega-thread. My favourite one was:

Yes, I admit { @1[@2] = “Go Fish: #{@2}” } is cryptic. But {@1 * @2} is not. So use numbered parameters with care (just like other features in Ruby). The possibility to make code cryptic itself should not be the reason to withdraw a feature.

The problem is introducing it or this could break existing code. That is the problem. Numbered parameters are a compromise to simplify block expression without breaking compatibility.

FYI, I am not fully satisfied with the beauty of the code with numbered parameters, so I call it a compromise.

– Matz

So, he accepted something that he wasn’t perfectly happy about. OK, I can understand the need for compromises from time to time. But I totally hate this line of reasoning “The possibility to make code cryptic itself should not be the reason to withdraw a feature.”. I think that adding features for the sake of adding them is not a reason to add something either.

I also think that we should be careful with the impact of features on tools and with all the accidental complexity they bring (e.g. now Ruby parsers are more complex). Not to mention the fact that no one could make a strong case for introducing this feature in the first place. I’m still not sure what’s the grand problem it solves…

The Totally Useless Pipeline Operator

This was probably the most ridiculous part of Ruby 2.7’s development cycle. At some point the pipeline operator landed in master:

# now
  .bar(1, 2)

# Ruby 2.7
  |> bar 1, 2
  |> display

Everyone who has actually used the pipeline operator in Elixir (the source of inspiration for this change), however, knows that it behaves nothing like this. Here Ruby’s team basically came up with different syntax for . (method invocation) with a lower precedence that allowed you to do questionable things like:

(a..b).each {}

a..b |> each {}

I won’t go into much details about this misguided operator. After all, a lot of great articles exist about it already.1 For me the important things here are:

  • This feature was not well thought-out
  • It generated a massive backlash
  • It was quickly reverted

Sounds familiar, doesn’t it?

The Rise and Fall of the Method Reference Operator

Ruby 2.7 was supposed to introduce a method reference operator:

[2, 4, 8, 16, 32].map { |n| Math.log2(n) }

[2, 4, 8, 16, 32].map(&Math.:log2)

Well, not anymore. This feature was recently reverted. There were some good reasons for it to be reverted, which serves to underline my point that a lot of changes to Ruby recently were made without thinking much about their implications. Matz, made one particularly interesting comment on this ticket:

In recent years, we have added/discussed a lot of features inspired by functional programming. But those features are not designed with a grand design. Those are rather ad hoc additions. We felt the future, more functional Ruby should be designed with the big picture of functional Ruby programming, which we lack currently.

Besides that, I don’t like the specific operator (.:) which looks like braille.

So you don’t have to consider this revert as a rejection of this whole idea, but an invitation to the next try.

– Matz

I was really glad to see this, as it seems that Matz also understands that without a solid vision in the end we’ll just get one big mess. I’m a bit sad about the .: operator being reverted, as this was a feature I could see myself using, but that’s a small price to pay for a better future of Ruby.

Parameter Forwarding Weirdness

Just when I had some hope about the future I came across another “brilliant” addition to Ruby 2.7 - parameter forwarding. It’s best explained with an example:

def foo(...)

This defines a method foo, that can have any parameters whatsoever and simply forwards all of them to bar. I don’t know about you, but I always wanted something like this!2

There are some plans to make it a bit more generic and support forwarding a subset of all parameters:

def foo(a, b, ...)
  if a.even?
    bar(b, ...)

Still, I think this is another random addition that doesn’t solve real problems and just adds mental and technical complexity.

A RuboCop Perspective

You might be wondering I am so grumpy about a bit of chaos during the development cycle of Ruby? After all it seems that most problematic features tend to get improved/removed.

I’m the author of RuboCop, a popular static code analyzer and formatter for Ruby, that’s why my perspective on all of this is probably different from that of many other people. Together with RuboCop and Parser’s team we actually have to support all of those language changes. Imagine how fun it is to add support for something, change this a couple of times, while tracking upstream changes, and then just delete it at the end. Or to have to do complex changes to support some new syntax that probably is going to be used by a handful of people… Trust me, that’s get frustrating after a while, and we’d definitely appreciate less turbulence in the design of the language.

You might say now - why don’t you just wait for the stable release of Ruby before implementing support for it? Have you ever seen users who don’t want support for the latest and greatest feature at day one? Yeah, I haven’t seen many of those either. :-) Not to mention that when you’re in the business of parsing code unknown syntax doesn’t result in a very pleasant end user experience.


So, we made it to the end of this somewhat bitter and rantish article. So, what’s the takeaway from all of this, if any?

It’s good that Ruby’s team listens to user feedback, but it might also be nice for them to actually start asking about feedback in some more open/structured manner prior to making language changes. Especially given their recent track record with the Ruby community… You can’t really expect everyone to be monitoring all tickets in Ruby’s issue tracker, right?3 I’ve often dreamt of a state where Ruby’s team actually announces in advance the focus for the next release (a.k.a. a roadmap), so interested parties can actually go and help with the tasks at hand. That should not require that much extra work - just a bit of good old planning. Some voting system on tickets and annual surveys might be a good idea as well - other programming communities are making good use of those.

Many people are excited about Ruby 3.0, but I’m not. It’s a major release in theory, but in practice it will add relatively little to what we have today. It’s not even clear if the new concurrent programming model will make it there or not at this point.

Ruby 2.7 has showed better than ever the chaos in Ruby’s development and the lack of a clear direction/destination. There are some signs that Matz understands this as well, so I’m still optimistic about the future.

I think Matz should take a page from Rich Hickey’s4 book and take a bit of hammock-time to figure out where he wants to take Ruby next. So, Ruby, where do we go now?

P.S. The article generated an interesting discussion on reddit. I encourage you to check it out.

  1. That’s my favourite one

  2. You can’t here my voice, but that’s sarcasm here. 

  3. Especially given the fact that the vast majority of ideas for language changes are just ignored and stay dormant for ages. 

  4. The author of Clojure.