MELT at the University of Minnesota

I was invited to the University of Minnesota today for a brief talk by Eric Van Wyk who presented over lunch about some of his research on extensible language tools. I was very surprised to find out that the research he has been doing is very similar to what I have been doing with meta#, they are working on ways to compose language extensions and create domain specific languages on top of general purpose languages. The details are different and some of them are very interesting and require further investigation but I am surprised by how much is not different.

Also, similar to the PPL and maybe even more so, he has a treasure trove of research papers on DSLs that I will have to read through.

Lang.NEXT 2012 overview

I had a great time at Lang.NEXT last week! There were a ton of amazing presentations and a lot of interesting conversations in between and after. There was a nice ongoing debate between native and managed languages and it was interesting to see some of what was going on in these fields.

What really interested me though was on the talks about Domain Specific Languages (of course). There was a talk about DSLs in Haskell and a talk on Bloom which is an internal DSL in Ruby and also a talk about R which is a DSL for statisticians.

But the one that really blew me away was the talk on pervasive parallelism in Scala, which turned out to be almost completely about the power of DSLs.

 

Specifically it was this slide that really got my attention:

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Which is a pick2 diagram for programming languages, positioning DSLs as the solution for the problem of Productivity and Performance.

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What was most amazing about this talk is that this is really the first time I’ve seen someone stand up and present DSLs with authority. And by that I mean someone who is making claims that are backed up by data and high quality research. When I talk about DSLs it’s based on my experiences and my intuitions and my understandings but not really very convincing data. The guys in the PPL however, really have some awesome papers on DSLs. I definitely felt validated to see such positive results and I hope this grants me some authority as well. When someone seems dubious of the promises of DSLs I can point them to the PPL and they can read for themselves the benefits that can be had.

In this talk Kunle Olukotun very clearly says that DSLs raise your level of abstractions and grant you a high level of developer productivity. He also brings up the very important concept of restriction in DSLs as a virtue. This is one very important fact that is not usually understood by advocates of internal-DSLs. Restriction is a very important key component to an internal DSL and is actually a virtue. From restricting the types you can use to what you can do with those types to the semantics and syntax of the language itself. For example, in a highly parallel application restricting your ability to mutate shared state is necessary, and making this restriction explicit in the language itself is actually a virtue of the language and helps to channel a developer into the path of least resistance. In many other languages they attempt to give you more features and less restriction but the opposite should be true for DSLs.

He even goes on to explain how patterns in the middle of their architecture can be considered ops for parallelism and how they use this for multiple DSLs. They even find overlapping parts of their domains that can be abstracted and shared between each other. This is really thinking about DSLs correctly, this is truly applying these ideas in a good direction. The PPL is using Scala for their runtime and they also use Scala to make restricted internal DSLs but I think this can apply for any language. He mentions that Scala has some good constructs for parallelism but also has some good features for making restricted internal DSLs. I think they ended up having to hack the Scala compiler some, but I am not completely sure.

 

One problem remains however… It takes about this many PhD students and faculty to make a DSL.

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I’m working on that.  🙂

Language Workbench Competition

I’m actually pretty close to having all of the MetaSharp grammars translated into .g files and Attila is working on the msbuild compiler components. Once we have them both done and merged we will have achieved dogfood status. There are plenty of Grammar and Lang features I want to work on still but the next major feature will be the Language Workbench, or in other words the interactive editor (I want to have some type of grammar REPL for the tclangug presentation I will be giving next month at least).

I just recently learned about the Code Generation Conference and now I am learning that there was also a Language Workbench website and that they sponsored a competition that went along with the conference. The most interesting part of this is the description of what a language workbench should do and how to rate them:

http://www.languageworkbenches.net/LWCTask-1.0.pdf

Which almost reads like a workbench spec! So this is very exciting, I have been thinking about what a MetaSharp workbench should be like and I think that I have a pretty good idea of what the external expectations are now, so this is good.

What’s funny about MetaSharp is that it is designed to solve all of the “Advanced” scenarios but currently doesn’t solve any of the “Basic” scenarios, lol. I’m not sure if that’s a good sign or a bad sign yet…