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PL Perspectives

Perspectives on computing and technology from and for those with an interest in programming languages.

In Spring 2020, I said to my mother: I wonder when we can go back to normal.  She replied: we should not go back to normal; we should go to something better.  Her words have become my angle on the virus: let us take the opportunity to make progress.  In particular, I wonder: can virtual conferences be better than physical conferences?  I will discuss what SIGPLAN is doing to make virtual conferences the best they can be, what SIGPLAN is doing on inclusion, and what ACM is planning for the future of publications and Gold Open Access. Let us begin with the new thing that has entered our lives as researchers.

Virtual Conferences

SIGPLAN people stepped up right away when the pandemic hit.  Crista Lopes and Benjamin Pierce, together with Jeanna Matthews from SIGOPS, co-led the ACM task force that in April 2020 wrote a widely read report on how to host a virtual conference.  Soon after, Alastair Donaldson (PLDI 2020) and Stephanie Weirich (ICFP 2020) each (with plenty of help) did a wonderful job of hosting an excellent virtual conference. My eyes were opened to how good such events can be.  In particular, I liked the Ask Me Anything events at PLDI 2020, and I liked the long discussions after each paper at ICFP 2020.  And who can ever forget the PLDI song or the ICFP song?  They were written by John Wickerson and by Youyou Cong and Jesper Cockx, and performed by all-star casts.  

SPLASH 2020, POPL 2021, and PLDI 2021 will all be virtual, too, and the organizers are working to make them exciting.

One thing in particular points the way to the future: Talia Ringer’s gigantic mentorship program at ICFP 2020.  I see it as a ramp-up of SIGPLAN’s mentoring breakfasts, which at POPL 2020 ran over three mornings and had a large room full of people each day.  But virtually we can go bigger!  Indeed the need is there: ICFP 2020 had almost 200 people express a desire for mentorship and they found that many kind and experienced SIGPLAN members were willing to be mentors.  

Costs and Fees

In Summer 2020, I joined the ACM Executive Committee, and my first task was to host two meetings for ACM and SIG leaders on best practices for virtual conferences.  We had the task-force leaders speak, of course, plus the general chairs of twelve 2020 virtual conferences, as well as the developers of platforms for virtual conferences.  One of those platforms is clowdr, created by Jonathan Bell, Crista Lopes, and Benjamin Pierce, and used by PLDI 2020, ICSE 2020, ICFP 2020, and others.  

What is the cost of hosting a virtual conference in the steady-state?  Virtual conferences have costs for such things as the platform, the publications, the tax to ACM, and possibly a conference manager.  ACM is starting a presidential task force, led by former SIGPLAN Chair Stu Feldman, which will look at such costs.

What is the right registration fee for a virtual conference?  For the physical conferences, we know the typical budget well and we have kept registration fees fairly stable for years.  For virtual conferences, if we can figure out the cost and find out whether companies will continue to support our conferences, can we settle on a registration fee that people are willing to pay?

I see this as the elephant in the room going forward. 

The Future: Virtual, Physical, Both?

We experienced this Summer that virtual conferences can make some things harder, compared to physical conferences.  For example, at a physical conference, one can meet a person and on the spot have a wonderful, technical conversation.  We need platforms for virtual conferences that can make casual encounters easier and more likely to happen.  Otherwise, people may opt to watch the conference on youtube later, rather than to participate actively.  

Participation is what we want most of all.  Both PLDI 2020 and ICFP 2020 had many more people registered than for their 2019 physical counterparts.  Indeed, no cost of travel and low registration fees encourage more attendance.  I love the inclusiveness of virtual conferences and I sense that we are reaching people well beyond our usual conference attendees.  

In the March 2020 issue of CACM, the SIGPLAN Climate Committee had an article about Conferences in an Era of Expensive Carbon.  In that article, we argued that every ACM conference should publicly account for the carbon emitted as a result of having the conference.  Let me take the opportunity to do this right now for the two SIGPLAN conferences that followed: for PLDI 2020 it was zero, and for ICFP 2020 it was zero as well 😃.  More seriously, climate change is real and we should think about it when we plan the future mix of virtual and physical conferences.  Meanwhile, ACM has improved its carbon offset program for conferences and we are eager to try it once we have physical conferences again.  However, virtual conferences are definitely good for the climate.

Do we like virtual conferences so much that we will never have physical conferences again?  Or, is the best future a mix of virtual and physical conferences?  Or, as soon as the virus is over,  are we done with virtual conferences?  The SIGPLAN Executive Committee welcomes your input; write your thoughts to any of us.


SIGPLAN has two recent initiatives on promoting inclusiveness.  First, looking ahead to physical conferences, SIGPLAN has created a pool of travel funding for members of historically marginalized groups.  An example of such a group is the faculty and students at Historically Black Colleges and Universities.  Another recent initiative is SIGPLAN’s CARES committee, which is a sounding board for anyone who experiences a violation of an ACM policy, such as discrimination harassment, or plagiarism.  The members of the committee, led by Kathryn McKinley and David Walker, are some of SIGPLAN’s most trusted and friendly people, and anyone of them will lend an ear to your concern without ever mentioning your name to anyone else, not even other CARES members.  

Publication Model

Recently, ACM started to develop the ACM Open model of publication, which is a variant of open access.  The idea is that the author or the author’s institution pays for the publication of a paper, while access to read the paper is free.  Also, ACM is working to ensure compliance with Plan-S in Europe.  So far, ACM has signed up universities such as MIT, University of Cambridge, and University of California for ACM Open, and ACM is working on signing up many more.  While ACM Open is maturing, ACM continues to charge a fee of $400 for Gold Open Access, and likely will continue to do so for at least five years.  We hope that authors themselves or their institutions can pay this fee, but SIGPLAN will pay for those authors who cannot.  The key body within ACM for overseeing and developing ACM’s publication model is the ACM Publications Board.  We are fortunate to have many SIGPLAN people on the board, including Jack Davidson, who is co-chair, and also Jonathan Aldrich, Chris Hankin, and Jim Larus.


Many volunteers are doing a lot of work for SIGPLAN and many have gotten involved in making virtual conferences delightful, innovative, and better than most of us dared to dream.  Do volunteer yourself!  The virtual conferences need volunteers, such as student volunteers, session chairs, and leaders of social events. Or sign up to run a PLMW, do climate-related data processing, or serve on an artifact evaluation committee.  Contact the general chair of the conference of your interest, or contact any member of the SIGPLAN Executive Committee. The reward is that you will enjoy working with great people who care about SIGPLAN and the future of our community.

Bio: Jens Palsberg is the chair of SIGPLAN, a member of the ACM Executive Committee, and a professor at the University of California, Los Angeles (UCLA). 

Disclaimer: These posts are written by individual contributors to share their thoughts on the SIGPLAN blog for the benefit of the community. Any views or opinions represented in this blog are personal, belong solely to the blog author and do not represent those of ACM SIGPLAN or its parent organization, ACM.