The Chronicle

of a ColdFusion Expatriate

What Is Good Software?

August 06, 2016

I’m an opinionated software engineer. I have strongly held beliefs about what makes a program good or bad (as I imagine most programmers do) but as a Vim user for 15 years who changed camps to Emacs, I’m on the front lines of a turf war that shows no signs of calming.

I believe strongly that “good software” is that which is fit for its intended purpose, and that has both benevolent maintainership and a strong community. Because there is nuance of interpretation in these words, I decided to write more.

Fair warning: this post is long.

When I say that Emacs is “better software” than Vim, I am not only remarking on the well-known instances of total insanity in Vim’s codebase, but more importantly on the Vim project’s reluctance to implement modern features even in the face of broad and vehement user support and its uncertain future as a project owing to its sole maintainer’s neglect of organizational foresight.

Let’s examine the strongest concrete example in recent events.

The Quest for Background Processing

As a proxy for the concept of “fitness for a particular purpose,” I want to talk about the ability of text editors to run background or asynchronous processes.

Perhaps the most coveted feature that the Vim project refused to add is support for some manner of asynchronous process handling, or an event loop, or job management, or something like that. For many years I suffered as Vim’s single process froze up completely while the Syntastic plug-in was running a syntax checker on the large file I was editing.

Vim users begged for the ability to run a process in the background and receive its output in a VimL callback function. A Yahoo engineer named Jonathan Palardy wrote slime.vim to send commands or text from Vim to another console or pane within GNU Screen (and someone else adapted it for Tmux). Ironically, Jonathan’s slime.vim is named for the Emacs package called SLIME, which provides an in-editor REPL for Common Lisp languages.

Intrepid Vim contributors even submitted patches to solve the problem. All attempts to make this dream a reality were turned away by Vim’s creator and sole maintainer, Bram Moolenaar.

Such was the state of affairs in the Vim world until January 31, 2014 when a young man by the name of Thiago de Arruda (tarruda on Github) boldly forked Vim and set out on a project he named NeoVim. In the world of open source software, a fork is either a compliment or an insult. I love it when people fork my projects because they are small and mostly unimportant, and usually it means that someone wants to contribute or cares enough that they want to play with customizing it themselves.

For Vim to be forked, though, in such an earnest manner, and with the intent not to submit patches but to diverge into a separate project, was one of the first real markers of bad project health.

The NeoVim project has had several releases beginning in late 2014 and is now considered to be quite stable, though it is still far from version 1.0. In the short time that the project has existed, it not only removed legacy preprocessor definitions and modernized the make system, but it added support for asynchronous job control, Lua scripting, and all sorts of other features that Vim users worldwide had only dreamed of.

It was just as NeoVim was reaching usable stability and gaining traction as a very real competitor to Vim that I began experimenting with Emacs and eventually gave the talk that made me (briefly) Internet famous. As a result, I never actually tried NeoVim myself (and quite honestly I have no interest in using it, though I’m still interested in its success as a project).

When I picked up Emacs, I discovered that it had all of the features that Vim lacked. Though my first couple of attempts in years past had been fraught with challenges that deterred me, I finally got Evil Mode working properly and swiftly discovered an equilibrium between Vim’s modal editing and Emacs’ peculiar modifier key karate.

Finally, in July of this year, one and a half years after NeoVim’s inception, Bram Moolenaar announced Vim 8.0. It now includes jobs, timers, partials (what I interpret to be a type of closure, sort of), lambdas, and actual package support. I can no longer say that Bram did not listen, but I can still criticize his early unwillingness and his “father knows best” attitude about code contributions.

Project Health

Emacs is great because it is at least as stable and mature as Vim, which it owes to its age and equally massive worldwide deployment, but it is also responsive to users’ requests and welcoming of their patches (sort of), and is even entering a bit of a renaissance as younger technologists discover that it is not simply Richard Stallman’s altar to the principled but often stifling philosophy of the GNU project, but a very capable and modern program indeed.

As a software project, Vim sucks because its creator and sole maintainer, Bram Moolenaar, keeps a deadly strangle-hold on the project and reserves the right of first refusal to incorporate enhancements or changes from the community. As I’ve cited many times in the past, Bram went as far as to say, in not as many words, that the best way to keep the Vim project alive is to keep him alive, which implies that he has no interest in sharing that responsibility with the vibrant community that grew around his project.

In contrast, the Emacs project has changed maintainers no fewer than two times since Richard Stallman wrote the program originally. Not only is this a testament to the breadth of the Emacs community, that we could find not one, and not even two, but three qualified and motivated individuals to steer the project toward its community’s common goals, but indeed a sign of the project’s health. We can sleep easily knowing that the Emacs project possesses the ability to pass the baton quite effectively should it become necessary.

When Bram Moolenaar is no longer maintaining Vim, for whatever reason, who will step up to the plate? Who will vet them? How will the community organize itself? Bram has not taken any steps to build a community ecosystem around his project and when the day comes that he is no longer in control, we can only guess at what may happen.

My prediction is that Vim development will slow to a crawl, ultimately doing nothing more than keeping up with security and stability patches, and that NeoVim will become the de facto standard for the general public.

Extensibility Wins the Day

The final point I will make in my now extremely long-winded treatise on the shape of great software, which has since devolved into yet another diatribe pitting Vim against Emacs on a playing field of personal opinion, is that extensibility is the single most important mechanism for solving most, if not all, of the disparities between these projects.

Vim is extensible through modification of its C code and through scripting in its built-in programming language called, officially or unofficially, VimL. Emacs is extensible through modification of its C code and through scripting in its built-in programming language called Emacs Lisp, a slimmer variant of Common Lisp.

Comparing VimL to Emacs Lisp is hardly fair; one is essentially an eccentric and fairly limited DSL with demonstrable performance concerns, and the other is a complete programming language in which approximately ¾ of the stock program’s functionality is implemented. You can do a lot in both of them, but VimL is limited in its usefulness because the majority of the way the program itself functions is below the VimL level, in the C code. Emacs, on the other hand, implements most of its editor behavior in Emacs Lisp and has a rich array of event hooks and a sort of “mix-in” system for hooking user-defined functions onto or around existing ones. The net effect is that nearly anything in Emacs can be changed, easily.

Of course this rings true to anyone familiar with the pejorative expression claiming that “Emacs is a great operating system, lacking only a decent editor.” It’s fair to say that it is possible to change Emacs in such dramatic ways that its flexibility can be almost comical when wielded without reason, but you only need to struggle with the desire to change some simple key mapping behavior or margin drawing functionality in Vim for a few hours before you start to appreciate the judicious application of hooks into lower-level functions.

The net effect of this is that the core maintainers of Emacs can refuse to implement certain features and, for the most part, the community can step in and do it themselves. Because VimL’s capabilities are much more limited, features like job management have taken years to make it into the hands of users.

What Michael says above is true, but the difference is that Evil Mode is implemented in pure Emacs Lisp and did not need the blessing of the project’s maintainers to get into the hands of its users. The timeline is coincidental; Evil Mode could have been created at any time. Vim 8’s new features had to wait until Bram could see far enough beyond his crippling hubris to descent from Mount Olympus with a patch in his hands.

In conclusion, great software is defined by more than its objective code quality; I would even go so far as to say that code quality is one of the least important characteristics of software. Especially in open source, the greatness of software lies in its ability to meet the needs of its users, and in its leadership and community to adapt to the changing landscape around it.