[ma_mazmaz]

In Scala, most variables should be val (i.e. constant) from a design perspective. That is, it is better, in Scala, to write code that does not have changing variable. Thus, using val instead of var is simply a check on the code, much in the same way that static typing provides a benefit over dynamic typing.

[StefanKarpinski]

> much in the same way that static typing provides a benefit over dynamic typing.

A non-trivial number of people would dispute that ;-)

[nrinaudo]

I don't think so, actually: in all the heated discussions I've had with people on the subject of static / dynamic typing, everybody agreed that static typing had significant benefits. What people don't agree on is whether these benefits are worth the cost.

It's hard to argue in good faith that having the compiler catch mistakes rather than finding about them at runtime is a bad thing. It's perfectly possible to argue that it's not worth the perceived development speed slowdown.

[actsasbuffoon]

Keep in mind that all of this is just my opinion. I'm not going to append "IMHO" to each sentence, as to save the reader the tedium of reading it. I'm not saying that I'm correct or that people should agree with me.

I would go so far as to say that I think overly simplistic static type systems don't have much benefit. C's static typing drives me crazy, as there's almost nothing of use that I can express with it. It's the same with Go; I almost never pass an Int when I meant to pass a Bool. In exchange for thoroughly unhelpful type errors I now have to jump through flaming hoops to parse JSON.

It ends up being a bit like JavaScript or Python where both languages lack the ability to specify that something is truly private (though in JS you can use closures to hide things). You generally just use a naming convention to mark a thing as private, and hopefully people have the decency to respect that. It's like that with types in dynamic languages; I can express pretty complex relationships with types and keep the whole thing in my head with out many problems.

That said, languages with powerful type systems like Scala and Haskell are thoroughly worth the effort. I can express almost anything with these type systems, usually with a minimum of fuss. They can protect me from the dreaded NPE, and that's a bug I encounter quite often. They can help me write simpler code that deals with complex shapes of data with their support for pattern matching and TCO. This one is more Haskell related, but the guarantee that everything is immutable and lazy makes it possible for the compiler to do some insanely impressive optimizations.

Scala, Haskell, and Rust have taken a dyed-in-the-wool lover of dynamic languages and made a convert of me. They finally followed through on the promises of safety and productivity that other languages failed to deliver on.

In closing, I'll repeat one last time that all of these are merely the opinions of an insufferable neck beard (me). Even if we disagree, I'm sure you're a very nice person, and I approve of you using whatever languages and tools make you happy and productive.

[nrinaudo]

I can't help but wonder whether you're that circumspect with everyone or if I come off as crazy-kill-you-you-phillistine and need to work on my communication skills?

Aside from the fact that I've never felt scarier, I agree entirely with every single point you just made and thank you for qualifying my broad generalisation.

[actsasbuffoon]

No, not in the slightest, though you've made me laugh like a maniac in front of my co-workers. So there's that, you fiend.

It was more of a general butt-covering sort of thing. People like to take offense to things on the internet.

[jbergens]

I agree with this. I also somethings think that I use the type system the most when I am refactoring/redesigning code and at that time I might be sending a bool instead of an int as someone wrote which is being caught by any good type system. Regarding the cost I think an optional type system, like in Dart, is intresting. You can do some prototyping or quick coding and then add types when you have some working code in order to develop fast, or you can use types all the time in order to be correct.