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Thoughts from Alan

My Compiler

The first commit I made for my compiler was in 2016, it read “Here’s hoping I get this done in time”. I’m not sure if I met the deadline that message was referring to, but the compiler is certainly “done” now.

Of course, no one in the right mind would use the compiler for anything serious, but the compiler compiles code, and I’ve made a simple graphical app launcher using it.

I mostly want to talk about the human aspects of this project. I find a lot of technical stuff in the project interesting too, but as somebody who is very much a novice at building compilers, I don’t think I bring much to the table talking about compiler construction.

How it started

I started the project in the summer of 2016. As a co-op student, I was supposed to intern at a company. Everyone seemed to have found jobs for the summer, but I didn’t. I felt really bitter that people who I considered less competent than me were able to find jobs while I was left jobless. I felt the need to get better, I felt resentment.

Thinking back, the reason I didn’t find a job was probably that I started searching too late. Most companies have filled their internship quota by the time I started looking. It turned out that resentment wasn’t a very effective fuel for me. I would put in an hour of work every day, even though I basically had nothing else to do. I wanted to build the compiler from scratch as much as possible, and there were a lot of problems I had to focus and think about for extended periods of time. Watching YouTube videos and playing games is much easier to do than thinking hard.

As much as I wanted to force myself to work on a project so I can impress potential employers, not much work was done on the compiler during the summer of 2016.

Reboot and critical mass

I stopped working on the compiler when the summer ended and didn’t work on it at all for most of 2017. In December of 2017, I got the idea to work on the compiler again. I wanted to prove to myself that I can build a compiler, I also wanted a sort of souvenir for my time at the university. Jonathan Blow’s compiler development livestreams were also a source of inspiration.

I got loops and procedures working in December. These two features, along with the support for conditionals I implemented in 2016, made the compiler feel tangible and actually sort of usable. Working on the compiler didn’t feel like a drag anymore, every commit felt like real progress.

How it got finished

I graduated from school in April of 2018. I had the privilege to take a 4-month break before starting work, so I used a lot of that time on the compiler. The compiler presented more and more interesting problems as it matured. Even though I reached my original goal of making an app launcher using my language, I kept working on the compiler because it proved to be an interesting sandbox for me to try out different ideas. The world was my oyster and I had the freedom and time to implement whatever I wanted. I had fun working on the compiler.

Was it worth it?

I am proud of my compiler. The code is nothing I would consider exemplary. Many would probably call it “unmaintainable”, and they would be right. However, I’m still proud of the project. I learned a lot working on this project and part of what I learned was why some of the decisions I made in the compiler were terrible. If I were to work on this compiler again, the first thing I would do is rewrite many parts of it.

I feel that I have overcome many obstacles and came out of the other side with two pieces of real, usable software. souvenir, the application launcher I made using the compiler, is installed on my machine at home and I use it every day.

I think I will always look back at the time I worked on the compiler fondly. Not many people get to write software just for the sake of it and I doubt I will get to do something like this again anytime soon. I am thankful for everything that contributed to this unique experience.