Category Archives: Types

“What is PL Research?” The Talk

I was invited to give a talk at the Programming Languages Mentoring Workshop (PLMW) colocated with POPL’19 in January. The talk topic was What is programming languages research? I was excited to give this talk. It’s a topic I’ve thought a lot about over the years; in 2015 I wrote a blog post about it. Shortly thereafter I was elected SIGPLAN Chair, and over the ensuing three years came to know the exciting depth and breadth of the field even more deeply.

Like the blog post, the talk presents what I view as the goals, ethos, and benefits of PL research. Because the PLMW audience is senior undergraduates and early graduate students, the talk also presents an overview of PL as a field. In particular, it presents a tutorial of sorts of the areas and methods that PL researchers often develop and employ. To capture what these are, I skimmed a sampling of the conference proceedings of PLDI and POPL from the last 30 years. Doing so, I abstracted the “shape” of a PL research paper, and identified the broad areas PL researchers tend to focus on. The talk presents a flavor of these areas. Because the talk took place just before POPL, I focused most on topics that appear in POPL-published research; the talk highlights particular POPL’19 papers as examples.

Several people afterward told me that they enjoyed the talk and asked about whether a video of the talk might be available. Unfortunately, the talks were not recorded. SIGPLAN main conference talks are regularly video-recorded, but workshops and co-located events are hit and miss. I certainly understand the financial reasons for this situation. Nevertheless, it’s really too bad that PLMW talks are not recorded. In my experience, PLMW speakers put an exceptional amount of time and care into their talks, so they are often very well done. The talks also target a general audience, so they are potentially valuable to many more people than just those attending the actual event.

In the hopes that others might find it useful, I decided to video-record myself giving the PLMW talk. The recording is not great, but I hope that fact doesn’t get in the way of the conveying the content. If it does, maybe just the slide deck will prove useful. If you have comments or thoughts, I’m glad to hear them!

Many thanks to the organizers of PLMW@POPL’19 for a great event, and the opportunity to speak!

The video. The slides.


Filed under Abstract interpretation, Process, Program Analysis, Research, Semantics, Types

Software Security is a Programming Languages Issue

This is the the last of three posts on the course I regularly teach, CS 330, Organization of Programming Languages. The first two posts covered programming language styles and mathematical concepts. This post covers the last 1/4 of the course, which focuses on software security, and related to that, the programming language Rust.

This course topic might strike you as odd: Why teach security in a programming languages course? Doesn’t it belong in, well, a security course? I believe that if we are to solve our security problems, then we must build software with security in mind right from the start. To do that, all programmers need to know something about security, not just a handful of specialists. Security vulnerabilities are both enabled and prevented by various language (mis)features, and programming (anti)patterns. As such, it makes sense to introduce these concepts in a programming (languages) course, especially one that all students must take.

This post is broken into three parts: the need for security-minded programming, how we cover this topic in 330, and our presentation of Rust. The post came to be a bit longer than I’d anticipated; apologies!

Software source code

Security is a programming (languages) concern

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Filed under Education, Software Security, Types

POPL’17 in Paris: Some highlights

Last week I attended the 44th ACM SIGPLAN Symposium on Principles of Programming Languages (POPL 2017). The event was hosted at Paris 6 which is part of the Sorbonne, University of Paris. It was one of the best POPLs I can remember. The papers are both interesting and informative (you can read them all, for free, from the Open TOC), and the talks I attended were generally of very high quality. (Videos of the talks will be available soon—I will add links to this post.) Also, the attendance hit an all-time high: more than 720 people registered for POPL and/or one of its co-located events.

In this blog post I will highlight a few of my favorite papers at this POPL, as well as the co-located N40AI event, which celebrated 40 years of abstract interpretation. Disclaimer: I do not have time to describe all of the great stuff I saw, and I could only see a fraction of the whole event. So just because I don’t mention something here doesn’t mean it isn’t equally great. 1

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  1. I also attended PLMW just before POPL, and gave a talk. I may discuss that in another blog post.


Filed under Program Analysis, Research, Scientists, Semantics, Software Security, Types

Interview with Matt Might, Part 2

Matt Might at the White House, Jan 2015

Matt at the White House, Jan 2015

This post is the second part of my March 10th interview of Matt Might, a PL researcher and Associate Professor in the Department of Computer Science at the University of Utah.

In Part I, we talked about Matt’s academic background, his PL research (including his favorite among the papers he’s written), and his work on understanding and treating rare disease, which began with the quest to diagnose his son Bertrand, and has led to a role in the President’s Initiative on Precision Medicine.

In this post, our conversation continues, covering the topics of blogging, privacy, managing a crazy schedule, and looking ahead to promising PL research directions. Continue reading

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Filed under Bioinformatics, Interviews, Language adoption, Probabilistic programming, Program Analysis, Scientists, Software Security, Types

Interview with Mozilla’s Aaron Turon

On the heels of Rust’s 1.0 release, we are pleased to be able to interview Mozilla’s Aaron Turon, a member of Rust’s core team (which is the leadership for the project that sets the overall direction). This is our third interview with a PL PhD working in industry.

Aaron Turon photo

Aaron Turon

What is your academic background?

I received my undergraduate degree at the University of Chicago, at a time where a lot of PL was happening (a lot of the folks who built or studied Standard ML were there); I did some research under John Reppy. After that, I went on to do a PhD at Northeastern University, which continues to have a thriving PL group; I was supervised by Mitchell Wand. Finally, I was a post-doc under Derek Dreyer at the Max Planck Institute for Software Systems (MPI-SWS).

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Filed under Interviews, PL in practice, Types

What is noninterference, and how do we enforce it?

In this post I discuss a program security property called noninterference. I motivate why you might like it if your program satisfied noninterference, and show that the property is fundamental to many areas beyond just security. I also explore some programming languages and tools that might help you enforce noninterference, noting that while tainting analysis won’t get you the whole way there, research tools that attempt to do better have their own problems. I conclude with some suggestions for future research, in particular with the idea that testing noninterference may be a practical approach.

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Filed under Program Analysis, Software Security, Types

Interview with Avik Chaudhuri

This is the first in a series of interviews we plan to do with programming languages researchers working in industry.


In this post, I interview Facebook’s Avik Chaudhuri, who has worked on language implementations at Facebook and Adobe (and is an alumnus of our group here at PLUM). Thanks, Avik, for taking the time to do this!

The interview is broken into three parts: Background; Facebook’s new language, Flow; and reflections on the value of a PhD and the challenges of research in industry. Continue reading


Filed under Interviews, PL in practice, Scientists, Types

What is type safety?

In response to my previous post defining memory safety (for C), one commenter suggested it would be nice to have a post explaining type safety. Type safety is pretty well understood, but it’s still not something you can easily pin down. In particular, when someone says, “Java is a type-safe language,” what do they mean, exactly? Are all type-safe languages “the same” in some way? What is type safety getting you, for particular languages, and in general?

In fact, what type safety means depends on language type system’s definition. In the simplest case, type safety ensures that program behaviors are well defined. More generally, as I discuss in this post, a language’s type system can be a powerful tool for reasoning about the correctness and security of its programs, and as such the development of novel type systems is a rich area of research.

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Filed under Dynamic languages, PL in practice, Semantics, Software Security, Types

Spotlight: Ravi Chugh

This post continues our ongoing series on young PL researchers who are about to start independent research positions in academia and research labs. This week, we  feature Ravi Chugh, who is starting as an assistant professor at the University of Chicago in the Fall. Continue reading

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Filed under Dynamic languages, Interviews, New scientists, Types