Technical Blog

Chorex: Guaranteeing Deadlock Freedom in Elixir

3 Jun 2024
Programming-Languages, Choreography, Computer-Science

Chorex is a brand-new Elixir library for choreographic programming [3]: Chorex provides a macro-based DSL that lets you describe how processes communicate to perform a computation. This top-down description of interacting processes is called a choreography. From this choreography, Chorex creates modules for each process that handle all the message-passing in the system. The interactions performed by the generated code will never deadlock by construction because the choreographic DSL ensures that no processes will be waiting on each other at the same time. ...

My Top Emacs Packages

30 May 2024

If you ask anyone what the best Emacs packages are, you’ll almost definitely hear Magit (the only Git porcelain worth using) and Org Mode (a way to organize anything and everything in plain text) listed as #1 and #2. And they’re right! I use those packages extensively every day. Besides those two powerhouses, there are a handful of packages that make using Emacs a delight. If I had to ever use something else, I would miss these packages most: ...

Boilerplate Busting in Functional Languages

6 May 2024
Programming-Languages, Macros, Programming

This is the story of how I solved a problem (ugly, cumbersome boilerplate code) that I ran into while writing a program in a functional language (Elixir). Functional programming languages often pride themselves on expressiveness and elegance; but occasionally they are not amenable to the most obvious solutions to the problems we wish to solve. In this case, the simplest solution to my problem would have been to have a global mutable variable. ...

Functional Languages Need Not Be Slow

20 Dec 2023

Somewhere in my adolescence I got stuck with the notion that functional languages were slow while languages like C were fast. Now, a good C programmer can eke more performance out of their code than probably anyone else, but the cost you pay to keep your code correct goes exponential as you get closer and closer to the machine. Functional languages abstract a lot away from the machine. Higher languages in general abstract away the machine and make code easier to maintain. ...

Towards Fearless Macros

13 Nov 2023
Programming-Languages, Macros

Macros are tricky beasts. Most languages—if they have macros at all—usually include a huge “here there be dragons” warning to warn curious would-be macro programmers of the dangers that lurk ahead. What is it about macros that makes them so dangerous and unwieldy? That’s difficult to answer in general: there are many different macro systems with varying degrees of ease-of-use. Moreover, making macros easy to use safely is an open area of research—most languages that have macros don’t have features necessary to implement macros safely. ...

Why Don't More Languages Have a call/cc Operator?

30 Oct 2023
Programming-Languages, Computer-Science

Something I’ve wondered about for a little while: why don’t more languages have a call/cc operator? Having first-class continuations in your programming language gives your programmers a powerful construct. So why do only a handful of languages have it? The short answer is: it’s tricky to implement efficiently. One way to get call/cc is to convert your code into continuation-passing style. Then, call/cc simply takes the continuation in that representation and binds it to a variable. ...

Deriving Recursion from First Principles

2 Oct 2023
Computer-Science, Programming-Languages, Racket

Or: Approaching the Y Combinator These are some of my class notes. Learning to derive the Y Combinator from first principles is something I’ve always wanted to do. This isn’t quite the Y Combinator, but it’s very close and it still gets you recursion without relying on recursive structures to begin with. In the beginning, we write a recursive function to compute the length of a list: (let* ([len (λ (lst) (if (null? ...

My Commitment to Intellectual Integrity

23 Sep 2023
Meta, Academics

I got a strange email the other day. Here it is, with parts redacted: Hi there, My name is G—, I am the main editor at —————. While browsing your site, I noticed you have an amazing article from this page: Link to an extremely old post of mine My team actually just published a comprehensive article on “Semi-related title” which I think your visitors would truly appreciate and add value to your awesome article. ...

Implementing Type Systems as Macros

14 Aug 2023
Computer-Science, Programming-Languages, Macros, Type-Checking

There’s a neat paper Type Systems as Macros by Chang, Knauth, and Greenman [1] that describes how to implement a typed language using an untyped host language and macro expansion. The paper is neat, but I found the code hard to follow—the paper uses a compact notation that’s convenient for print, but not so much for reproducing on one’s own. This post is my attempt to implement and explain in more accessible terms what’s presented in the paper. ...

Reflections one year into a PhD program

5 Aug 2023
Computer-Science, Education, Career, School, Personal

I started my PhD program about a year ago. In my first year I have: Taken 4 “normal” 3-credit-hour classes Participated in 3 seminars Switched advisors Attended 2 conferences (PLDI @ FCRC, JuliaCon) Presented my work at JuliaCon It’s been a lot of work, and there’s been a lot of stress. I’m in a much better place now than when I started, and over all I’m happy where I’m at and where I’m headed. ...