In Defense of Programming Languages

This blog post is written in defense of programming language enthusiasts; whether they are compiler hackers, programming language hobbyists, industry professionals, or academics.

In this blog post, I want to examine the discourse around programming languages and especially how new programming languages are received. My hope is to improve communication between programming languages designers and software developers. I understand that we cannot all agree, but it would be fantastic if everyone could at least try to be friendly, to be intellectually curious, and to give constructive feedback!

A Few Quotes from the Internet

Let me set the stage with a few quotes from social media tech sites (e.g. Reddit, HackerNews, Twitter, etc.). I have lightly edited and anonymized the following quotes:

"Great! Yet-another-programming-language™. This is exactly what we need; the gazillion of existing programming languages is not enough!"

— Furious Panda via Reddit

"This is – by far – the worst syntax I have ever seen in a functional language!"

— Irate Penguin via Reddit

"The language is probably great from a technical point of view, but unless Apple, Google, Mozilla, or Microsoft is on-board it is pointless."

— Angry Beaver via HackerNews

"How can anyone understand such weird syntax? I hate all these symbols."

— Bitter Turtle via Reddit

"The examples all look horrible. The site looks horrible. This needs a lot of work before it gets close to anything I would even consider using."

— Enraged Koala via Twitter

While all of the above quotes are in response to news about the Flix programming language (on whose website you are currently reading this blog post), depressingly similar comments are frequently posted in response to news about other new programming languages.

Why do people post such comments? And what can be done about it?

Where do such comments come from?

I think there are two reasons which are grounded in legitimate concerns:

• Fatigue: I think there is a sense that there are new programming languages coming out all the time. Paradoxically, I think there is both a dread of having to keep up with ever-changing programming languages (and other technologies) and simultaneously a sense that these new programming languages are all the same.

• Speech: Programming languages are the material with which we craft programs: It is our way of "speaking" algorithmically. They are about what we say, how we say it, and even what can be said. Like prose, what is beautiful and elegant is in the eye of the beholder. It is not surprising then that when a new programming language comes along and suggests a different form of expression that some may have strong reactions to.

Of course there are also internet trolls; but let us ignore them.

A Point-by-Point Rebuttal

I want to give a point-by-point rebuttal to the most common refrains heard whenever a new programming language is proposed.

Do we really need new programming languages?

The Flix FAQ joking responds to this question with a rhetorical question: Do we really need safer airplanes? Do we really need electric cars? Do we really need more ergonomic chairs?

I think it is a valid argument. We want better programming languages because we want to offer software developers better tools to write their programs. You might say that existing programming languages already have all the feature we need, but I think that there are exciting developments; both brand new ideas and old research ideas that are making their way into new programming languages:

• Safety: region-based memory management, lifetimes, ownership types, linear types, 2nd class values, and capabilities.
• Expressiveness: union and intersection types, polymorphic effect systems, algebraic effects, type-driven development, increasingly powerful type inference.
• Development Experience: the Visual Studio Code ecosystem, the language server protocol, GitHub code-spaces.

I don't think we are anywhere near to the point where programming languages are as good as they are ever going to get. On the contrary, I think we are still in the infancy of programming language design.

All programming languages are the same

I strongly disagree. I think we are experiencing a period of programming language fragmentation after a long period of consolidation and stagnation. For the last 15-years or so, the industry has been dominated by C, C++, C# and Java. The market share of these programming languages was always increasing and they were the default safe choice for new software projects.

Today that is no longer the case. The ecosystem of programming languages is much more diverse (and stronger for it). We have Rust. We have Scala. We also have Go, Python, and JavaScript. There is also Crystal, Elixir, Elm, and Nim (Oh, and Flix of course!) We are in a period of fragmentation. After a decade of object-oriented ossification we are entering a new and exciting period!

If history repeats itself then at some point we will enter a new period of consolidation. It is too early to speculate on which programming languages will be the winners, but I feel confident that they will be much better than C, C++, C#, and Java! (Ok, maybe C++30 will be one of them – that language changes as much as Haskell!)

(Addendum: That said, it is true that many hobby programming languages look the same. But there is a reason for that: if you want to learn about compilers it makes sense to start by implementing a minimal functional or object-oriented programming language.)

New programming languages are too complicated!

That's the way of the world.

What do you think an airline pilot from the 1950's would say if he or she entered the flight deck of an Airbus A350? Sure, the principles of flying are the same, and indeed iteration and recursion are not going anywhere. But we cannot expect everything to stay the same. All those instruments are there for a reason and they make flying safer and more efficient.

As another example, once universities start teaching Rust (and we will!) then programming with ownership and lifetimes will become commonplace. As yet another example, today every programmer can reasonably be expected to know about filter and map, but that was certainly not the case 15 years ago!

A programming language cannot be successful unless a major tech company is behind it

Historically that has not been true. Neither PHP, Python, Ruby, Rust, or Scala had major tech companies behind them. If industry support came, it came at a later time.

Ideas for Better Communication

With these points in mind, I want to suggest some ways to improve communication between aspiring programming language designers and software developers:

When presenting a new programming language (or ideas related to a new language):

• Scope: State the intended scope of the project. Is it a hobby project made for fun? Is it an open source project hoping to gain traction? Is it a research prototype? Is it a commercially backed project? What is the intended use case? Is there a "killer-app"?

• Implementation: What has been implemented? A compiler? An interpreter? Do you have a standard library? How big is it? How many lines is the project?

• Novelty: What is new in the programming language? Are there some new takes on old ideas? Is there something novel? How is the language an improvement compared to existing languages? Does the language make you think in a new way about programming?

• Resources: What resources are behind the programming language? Is it a hobby project? An open source project? An academic project? Are you open to collaboration? Do you have backing (from industry or otherwise)?

• Feedback: What kind of feedback are you looking for? What other people think? Suggestions for improvements and related work? Constructive criticism about the design? What it would take for someone to consider using it?

• Reality Check: Try to avoid grandiose or unsubstantiated claims: Do your compiler really outperform modern state-of-the-art C compilers? Is your type system really more expressive than Haskell or Idris? Is your language really safer than Ada?

What about Flix?

The time has come to nail our colors to the flag:

• Scope: We are building a real programming language intended for real-world use. It is an open-source project lead by academic programming language researchers.

• Implementation: The Flix compiler project is ~137,000 lines of code. We have a realistic compiler, a standard library (extensive, but still under development), a Visual Studio Code extension (with auto-complete!), an online playground, online documentation, and several published papers on the novel aspects of the language.

• Novelty: We have a whole page (Innovations) that covers this, but briefly: a unique combination of features, combined with first-class Datalog constraints and a polymorphic effect system.

• Resources: We are a group of programming language researchers from Aarhus University and the University of Waterloo together with a small community of open source contributors. Through our research we have funding for working on Flix.

• Feedback: We want to know what people think about Flix, how we can make Flix better, and what it would take for someone to consider using it.

• Reality Check: We aim to under-promise and over-deliver. We do not promote features before they exist. Our typical pipeline is: (Research) Idea → Implementation → Documentation → Presentation to the World. Development is not secret; everything is on GitHub. We just don't promote anything before it is ready. We have exciting things in the pipeline, but you will have to wait a bit before learning about them (or spoil yourself by diving into the GitHub issues!)

Until next time, happy hacking.