design

Type systems... We all know they are cool. In a static language, like Kotlin, the type system is the one responsible for early detection of errors. Many tools (e.g. an IDE with its refactoring abilities) also rely on the type system. We also know that type systems are hard: many computer scientists…

Kotlin is designed so that there's no such thing as a "static member" in a class. If you have a function in a class, it can only be called on instances of this class. If you need something that is not attached to an instance of any class, you define it in a package, outside any class (we call it pac…

In Kotlin M5 we have redesigned our ranges a little bit. (more…)…

It's been a while since I blogged last time on Kotlin M2. Now, the hot summer has passed, and M3 will be out very soon. In this post I describe two small features added in M3 that make our lives easier and will lead to simplification of the language. How do you traverse a map? Assume you have a ma…

As the first public preview of Kotlin is approaching (it will be announced on Jan 10th, 2012, which is less than a week from now!), we are putting some things in order... In particular, we have reviewed syntactic forms available in the language, and decided to change a few. These changes are incomp…

A post about good books, language design and JIT compilation, in which one bug turns into another and than back... Recently I started looking through an excellent book "Java™ Puzzlers", where Joshua Bloch and Neal Gafter provide a list of Java's "Traps, Pitfalls, and Corner Cases", i.e. programs t…

If you have a very nice API, it is the fashion nowadays to call it an internal DSL, because the code that uses such an API reads almost like a language inside your language of choice. Fluent interfaces serve as one of the most popular examples. Many modern languages provide some advanced means for …

In the previous post in this series we discussed the disadvantages of the inheritance model we initially planned for Kotlin. Today we will talk about alternative designs. Note that these posts are intended to provoke a discussion, so that we can benefit from your feedback and come up with a better …

I'm back from my vacation, and it's time to get to one one the biggest issues pointed out in the feedback we received during conference presentations and in the comments to the docs. I'm talking about inheritance. I plan to write a series of posts on this topic. These posts are intended to provoke …