FP and LISP for the rest of us

As a developer with a traditional C++/Java background and a non-CS major I find the recent surge in popularity of functional programming pretty confusing. It turns out that there is a whole parallel universe of FP where most hard-won imperative experience is of little help in understanding new concepts. And those are frequently hidden behind bizarre syntax.

I have stumbled upon a couple of very well written articles on FP and LISP . The author starts from something as trivial as Java and Ant and ends up explaining, say, the power of LISP. Very approachable with quite a few insights.

Date and time in Java

Today I was fixing a bug which revealed a problem in how we incremented dates (yes, by adding 86400000). Naturally, it led to corrupted data after recent switch back to Pacific Standard Time from Pacific Daylight Time. I had to go review a very good overview of time-related Java issues and play with a date calculator.

Frankly, it's still rather counter-intuitive to me how much complexity is behind seemingly innocent long timestamps. What could be simpler than milliseconds passed since 1970? ;)

Event Stream Processing

I have just stumbled upon this new approach to event-based design. A wikipedia example says it all in 7 lines. The idea is to use an SQL-like language to create filters (capable of event correlation, typically limited to a certain period) and run a continuous stream of events through them. There is even an open source implementation. At first glance most currently available products are used in algorithmic trading (whatever was left of it after the crisis :) ).

To me this concept seems to be a kind of rule engine and so potentially there are multiple domains where it might be applied. On the other hand it makes me wonder whether it is indeed a re-packaged rule engine and in such a case what is so different about it.

Performance is the name of the game because ESP is positioned as a soft real-time technology. It must be pretty interesting to read how they manage to achieve their declared ability to process a huge number of events per second on commodity hardware.