Basildon Coder

Weiqi Gao has a post up today discussing the trials of grokking Scala. Scala is a language I want to take a much closer look at later this year, since I want to become current on the JVM again (having not been on talking terms with it since using J2SE 1.4 around the summer of 2003) without being particularly keen on tangling with the Java language itself.

One of the key features of Scala is the functional programming style it brings to the JVM. It’s actually quite common to use certain functional idioms in Java - e.g. passing around a function as a parameter - but the syntax is clunky and verbose (unless and until closures get confirmed in 1.7, that is, and maybe even then).

For example, take a look at this very simple idiomatic code for spinning off a thread to perform an expensive operation:

new Thread (new Runnable() {
    public void run() {
        someObj.doExpensiveOperation();
    }
}).start();

Now that’s not the most hideous code I’ve ever seen, but it’s a bit…wordy. Compare it to this equivalent implementation in Java’s closest mainstream relative, C#:

new Thread(x => someObj.DoExpensiveOperation()).Start();

I much prefer this syntax, even taking into account the throwaway lambda parameter that’s only there to satisfy the ThreadStart signature. The Scala syntax is even nicer, however:

spawn({ someObj.doSomethingExpensive })

This is the sort of thing that piques my interest about the language - expressive syntax and a very funky concurrency model will get my attention, especially when running on something as mainstream as the JVM and with full interoperability with the frankly staggeringly-vast Java library ecosystem. I like F# on the CLR for similar reasons.

But I digress; what I wanted to talk about was a point made by Weiqi, when discussing the pattern-matching capabilities of Scala:

Pattern matching in Scala is exactly the point at which I would spend time trying to understand it, trying to master it, trying to learn to use it. I understand the syntax. I understand the explanation that the speakers in presentations gave. I do get to the part where I say “This is cool.” But I never get to the point where I would see a problem and say “This problem is best solved with pattern matching, let me fire up Scala and code the solution.”

This strikes a chord for me, as I have gone through that stage once or twice myself with other features in other languages and yet can’t quite put my finger on how I get past it. I don’t think it’s something you consciously do - it’s just something you keep grafting away at until suddenly you realise that the technique, whatever it is, has become part of your armoury.

Closures are an obvious example I can think of in my own background. I was raised as a straight-down-the-middle C++ man, way back in the early/mid-90s, cutting my teeth on Borland Turbo C++ 3 on Windows 3.1. When I first started to play with functional languages it took a long time for me to ‘get it’, and even when I understood what a closure was after a couple of weekends hacking around in OCaml, I couldn’t envisage when I’d ever need one.

Soon after, whilst working on a Konfabulator widget in javascript, I noticed I was using them all the time. I suddenly had much more insight into what ruby blocks were doing. It wasn’t so much that I noticed the lights go on - they’d been on for some time and I hadn’t realised.

People commonly refer to the ‘lightbulb moment’ or ‘the lights went on’ as being the point where a flash of inspiration hits and everything suddenly makes sense. I don’t like this metaphor. If I need to go to the bathroom in the middle of the night, when the lights go on I squint in pain and stagger around just as blindly as I did before. But then I acclimatise, and all becomes clear. And so it is, I think, with learning alien concepts - you need a bit of time to adjust to the dazzling light.

This entry was posted on Tuesday, March 25th, 2008 at 6:06 pm and is filed under Coding, Software Engineering. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.