Jetbrains Kotlin demo running online

Jetbrains have posted an early demo of their Kotlin language online.

http://kotlin-demo.jetbrains.com/

They're aiming for the JVM and compiled Javascript, and are looking for developer feedback.

Having played around with it for a bit, I certainly prefer the syntax to Scala, but that's probably just because I'm more familiar with Java.

Looks like the kind of thing someone who'd only ever programmed in Java would design if they were trying to make something 1% better than Java. It's ugly and pointless.

They couldn't get the demo landing page to render properly in IE9 it seems ... not an encouraging introduction. 

12 hours ago, rhm wrote

Looks like the kind of thing someone who'd only ever programmed in Java would design if they were trying to make something 1% better than Java. It's ugly and pointless.

I imagine the reason it looks like Java is the same reason that C# looks like Java and Java looks a lot like C++: developer familiarity.

Does make me wonder why they have decided to put colons all over the place. Doesn't do wonders for readablity in my opinion.

8 hours ago, Richard.Hein wrote

They couldn't get the demo landing page to render properly in IE9 it seems ... not an encouraging introduction. 

Very true, but it's possible that their target market doesn't use IE for development.

System.out?.println("Hello, world!")

...not pretty to look at even a Hello World example 

5 hours ago, Ray7 wrote

*snip*

Does make me wonder why they have decided to put colons all over the place. Doesn't do wonders for readablity in my opinion.

Apparently, Pascal postfix typing is all the rage these days, not sure why. That's one of the mistakes lots of wannabe Java killers are making... they add a few long needed features to the platform, and tons of syntax sugar, but they shoot themselves in the foot imposing an alien syntax.

This said, the language includes a couple of features that I'd like to see in C#... the most interesting being the automatic type inference in code, as in:

if (o is Foo) {
  o.SomeMethodUniqueToFoo();
}

It's the mathematical type syntax. They want to be "pure" as close to mathematics as possible, and trying to correct this "mistake" of infix notation. That's probably why.

10 hours ago, Bass wrote

It's the mathematical type syntax. They want to be "pure" as close to mathematics as possible, and trying to correct this "mistake" of infix notation. That's probably why.

Well there's maths and there's programming.

I find this:

myStr : String = s

less readable than this:

String myStr = s

17 hours ago, Harlequin wrote

System.out?.println("Hello, world!")

...not pretty to look at even a Hello World example 

That is very very odd.

I think it's because, by default, Kotlin objects are not allowed to be null, unless you say it is nullable when you declare it and you need to use the dereferencing checker (?.) when you access it.

I imagine they are using the standard JVM library, which must be chock full of nullable types.

They'll need to fix that, or it's going to make for some really messy source code.