True Scala complexity

Second, I think the blog post is useful because it shows what's wrong with some (fortunately very small) part of the Scala ecosystem, and because it points to a way to fix it.

Here's a quick recap: The author tries to add arbitrary operations to Scala's Seq abstraction without changing its source code and wants them to work also on arrays (which are plain old Java arrays), without any extra work. Arrays in Java support: length, index, and update; that's it. There is as far as I know no language in existence that allows the precise thing the author wants to achieve. And there are many variations, such as adding only to Seq or only to Array that would be really easy in Scala but still impossible in most other mainstream languages. The author then throws all the machinery he can think of at the problem to still achieve the same non-result. Well, tough luck. He might have hit a thing that's simply impossible to do in a generic way, given the tools we currently have. In fact, I have not checked whether there would be a way to achieve the result that he wants because that's beside the point. There are always limits to a generic formulation that will force you at some point to treat things on a case by case basis.

The problem is that, in trying to achieve his impossible goal, the author (mis-)uses a lot of the most powerful features of Scala, and concludes that Scala is simply too complex for helping him achieve the result. I believe he wrote this blog post to prompt the maintainers of Scala to add even more power to the language so that he can achieve his goal (the only other motivation I can think of is that he's trying to actively damage the ecosystem he writes code in, but that would make no sense to me).

My response will probably not please him. I think that we need to take away sharp knifes from people who have a tendency to cut themselves. I was always proud that in Scala you could do in a library where in other languages you had to change the compiler. Inevitably, some of this is cutting edge stuff. We have tried many times to clarify the boundaries, for instance when I defined the Scala levels

http://www.scala-lang.org/node/8610

But we can't prevent a developer who prides himself to "stroll right through level L3" to get hurt.

So, I believe here is what we need do: Truly advanced, and dangerously powerful, features such as implicit conversions and higher-kinded types will in the future be enabled only under a special compiler flag. The flag will come with documentation that if you enable it, you take the responsibility. Even with the flag disabled, Scala will be a more powerful language than any of the alternatives I can think of. And enabling the flag to do advanced stuff is in any case much easier than hacking your own compiler.

I would be interested to read your comments on this proposal.

Yes, I love the idea. I've said so before on hackernews and on the scala-user mailing list; it would be a huge contribution to Scala.

Most of these features (implicits, higher kinded types, and hell, it's not complicated but ugly so I'd throw it in: using symbols as method names) are useful for library designers, but less so for your average project.

I've written a few thousand line Scala application that has so far made awesome use of first class functions, pattern matching, and actors. I can't think of another language that would work as well for me, and I haven't had to resort to any of the advanced features the author talks about.

What i'm terrified of is having patches/contributions that make use of these 'complex' features that might scare away newbies from hacking on the project.

I think having a 'version' of Scala (enforced by the compiler) that was as simple for beginners to use as Gosu, Kotlin, Ceylon etc. would go a long way in Scala evangelizing, and unlike the aforementioned languages, they wouldn't be as constrained as they grew as developers.

Speaking as someone who sometimes writes controversial things and never enables comments on my posts...

I view collections of comments as discussions. Readers often form into communities, like Hacker News. If there are comments on a blog post, are you supposed to write your comment here in your community? Or there on the post? Well, a good question is, are you a member of the author’s community? Probably not! Communities have all sorts of standards for participation. What are the author’s standards? Why bother figuring them out for one comment?

Communities also have other tools like seeing a person's history of posts to get a sense of their viewpoint and biases. How do you do that on an author’s blog?

Ultimately, authors either have to get rid of comments or buy into a plug-in system like Disqus. In my own case, I usually just provide a link to HN for posts that I think are of interest to the folks here. Everyone else can use twitter, reddit, or their own blogs to continue the discussion.

That doesn’t mean I won’t read all the flames, there are no end of analytics tools for discovering what people are saying about my writing.

I don’t speak for this author, but considering he has a link to this discussion right at the top of his post, I’m guessing he’s listening to your thoughts and welcomes your feedback right here or wherever people congregate to discuss the news of the day.

If people/teams decide they don't want to use aspects of the language then they are free to do so by convention.