FTfJP and the DLS

So on to day 2 of the conference, where I mainly attended FTfJP and briefly popped into the Dynamic Languages Symposium.

First of all I'd like to bing attention to my colleague, Alex Summers' talk, which was a good talk, but more importantly the work is interesting. Actually I have been a little bit involved with it (only a little though) so I have heard a lot of teh stuff he talked about. But, I think it is very interesting, it is about adding static fields and methods to the universe type system. Frankly, I think this is a terrible idea, we should just avoid static anything like the plague (see Gilad's summer school talk and (I think) an earlier blog post), but if you're going to do it, then it turns out to be an interesting problem with no easy solution (the best kind, or worst, depending on your point of view).

The next great talk was by Stefen Wehr who talked about wildcards (a topic very close to my heart). He is concerned with decidability, admitedly not directly. In his work he shows that _a_ model for wildcards and another for interfaces in JavaGI, both of which use a similar kind of existential type, are undecidable. This is obviously interesting since decidability of wildcards is still an open question, which I'd love to look at if I had the time and skills, but I have neither, so I have to make do with reading interesting papers like this one.

The next talk of note was at the DLS, it was an invited talk given by Laurence Tratt entitled Language Design: Back to the Future?. The gist of the talk was that all current languages are almost identical and language designers are not really being creative. He also claimed there are some valuable things that people have done and that have been ignored. I kind of agree, although I don't agree that it is due to a lack of creativity on the part of language designers - there are plenty of fairly wild ideas floating around, but it is true that most never make it into real life languauges. He seemed to concentrate on 'micro' level language features such as new expressions, which is an area (I thinK) that has been neglected in research lately in favour of more 'macro' ideas - such as ownership types, different object meta-models etc. I was a little inspired by the speaker to think a bit more about language culture. His point is that programmers, lanaguage designers, and researchers are all absorbed in a certain culture of a language - the paradigm, the programming idioms, way of thinking, etc. It would be interesting to see some research on this - to charecterise and compare these programming cultures and the effects they have on programming languages, and importantly, vice versa. A quote I liked was that innovative language features were destined to have "some spotty twat at the front take the piss out of it".

I'm afraid that by this point I was a little drained and failed to make any meaningful notes, but I'd like to draw attention to the last two talks of the day that I thought were interesting - Rok Strnisa on the Java Module System and Samir Genaim and Fausto Spoto on constancy analysis

And an interesting thought from one of the talks - if we have an underlying database implementation (for example) that only has a next method as an accessor that returns null at the end of the table. If we wish to implement a wrapper with a hasNext method, then this method will have an internal side effect (it must cache the returned row, if it is not null), but logically it should be pure. Can this be handled elegantly in the various ownership/invariants/effects systems that are around?