I am working at the School of Computing
at the University of Kent.
My work focuses on programming language implementation techniques
and concurrent and parallel programming.
Currently, I am working on fast dynamic language implementations,
on combining concurrency models in a safe manner,
automatically preventing concurrency issues from manifesting,
and to enable developers to make sense of complex concurrent programs
with appropriate tools.
Here at Kent, we have a large group of researchers working on Programming Languages and Systems (PLAS), and within this group, we have a small team
focusing on research on interpreters, compilation, and tooling to make programming easier.
Motivated by Tiger, a tool for generating interpreters, being mentioned
on Twitter,
I had a brief look at vmgen, Tiger, eJSTK, Truffle DSL, and DynSem.
What follows are my rather rough notes and pointers.
So, this is by no means a careful literature study,
and I welcome further pointers.
I started writing this post when being very very annoyed by this blog post on the SIGPLAN blog.
I could not understand how “THE SIGPLAN” blog
could simply write 30 years of
programming language research out of existence,
only barely acknowledging Self and JavaScript.
It felt like duty called…
Last year, I was asked to give a talk for the Meta’19 workshop.
It’s a workshop on metaprogramming and reflection.
The submission deadline for this year’s edition, is less than a month away: Check it out!
Last September, I had a lot of fun putting together a lecture on
language implementation techniques. It is something I wanted to do for a while,
but I had not had a good excuse before to actually do it.
Disclaimer: The artifact, for which I put this automation together, was rejected.
I take this as a reminder that the technical bits still require good
documentation to be useful.
SOM, the Simple Object Machine, is a little dynamic language designed for teaching
object-oriented virtual machine design.
It originates in Aarhus, Denmark, and according to Lars Bak,
it was implemented in the course of two days by Kasper Lund.
They used it back in 2001 for a course at the University of Aarhus.
Debugging concurrent systems is pretty hard,
and we worked already for a while to make things a
bit better.
However, a big remaining problem is that bugs are not easily reproduced.
Programming languages naturally come with a library of containers or collection
types. They allow us to easily work with arbitrary number of elements, which is
something all major languages care about. Unfortunately, it seems like there is
not much writing on how to design such libraries. Even asking a few people that
worked for a long time on collection libraries did not yield much of a
structured approach to such a central element for our languages.
The one major piece of writing we found is the Scala people describing
their experience with bit rot and how they redesigned their
collection implementation to avoid it.
When we have to debug applications that use concurrency,
perhaps written in Java,
all we get from the debugger is a list of threads,
perhaps some information about held locks,
and the ability to step through each thread separately.
Research on programming languages is often more fun when we can use our own languages. However, for research on performance optimizations that can be a trap. In the end, we need to argue that what we did is comparable to state-of-the-art language implementations. Ideally, we are able to show that our own little language is not just a research toy, but that it is, at least performance-wise, competitive with for instance Java or JavaScript VMs.
The first results of my experiments with self-optimizing interpreters was finally published in IEEE Software. It is a brief and very high-level comparison of the Truffle approach with a classic bytecode-based interpreter on top of RPython. If you aren’t familiar with either of these approaches, the article is hopefully a good starting point. The experiments described in it use SOM, a simple Smalltalk.
Today at FOSDEM, I gave a brief talk on implementing SOM, a little Smalltalk, with RPython and Truffle. RPython, probably best known for the PyPy implementation, uses meta-tracing JIT compilation to make simple interpreters fast. Truffle, a research project of Oracle Lab, is an approach for building self-optimizing interpreters and in combination with Graal, it gives a JIT compiler for AST-like interpreters. In the talk, I briefly sketch both of them, without going into many details.
Last Friday, I defended my PhD dissertation. Finally, after 4 years and a bit, I am done. Finally. I am very grateful to all the people supporting me along the way and of course to my colleagues for their help.
My second talk at Smalltalks 2012 was most likely the reason why the organizers invited me in the first place. It was a slightly extended version of the Sly and RoarVM talk for the FOSDEM Smalltalk Dev Room from the beginning of the year, reporting on the Renaissance Project.
My paper, on how to support various concurrency models, with an ownership-based meta-object protocol (MOP) was accepted at TOOLS’12. Below, you will find a preprint version of the paper. A later post will provide details on how to use it and how to experiment with the MOP in Pharo 1.3.
As preparation for SPLASH’11, here my paper for the VMIL workshop. It is a position paper discussing in which direction virtual machines should evolve in the future with regard to the challenges manycore architectures and concurrent programming bring.
Today, I gave a talk at the ExaScience Lab, Intel Labs Europe in Leuven at IMEC. I talked mainly about the idea of nondeterministic programming, the Sly programming language and some details on our Smalltalk manycore virtual machine that enables those experiments. Thus, tried to spread the word about our Renaissance project at bit further.
Last Friday was the annual Lab event of our Software Languages Lab. Like last year, many people related to the lab in one or the other way came to get an overview of what the current topics of our research are.
On the first day here at the summer school, the organizers gave us the opportunity to present our research ideas to the lecturers and other participants.
Already quite a while ago, I was involved in writing a workshop paper about an actor model for virtual machines. Actually, the main idea was to find a concurrency model for a VM which supports multi-dimensional separation of concerns. However, AOP is not that interesting for me at the moment, so I am focussing on the concurrency, especially the actor-based VM model.
My second workshop paper got published at the ACM Digital Library. This is actually only an abstract, but nonetheless, it might be interesting for people looking into the design of virtual machines and especially bytecodes/intermediate languages.
Finally, my first workshop paper got published, which was a little odyssey with some misunderstandings, but anyway, now it is out. It is just a position paper, thus, do not expect to many insights. However, what it describes is my big plan, and hopefully the story of my PhD. Am working on it…
I am working at the School of Computing
at the University of Kent.
My work focuses on programming language implementation techniques
and concurrent and parallel programming.