Kotlin is a statically typed language that targets the JVM and JavaScript. It is a general-purpose language intended for industry use.

It is developed by a team at JetBrains although it is an OSS language and has external contributors.

Kotlin generates bytecode which is compatible with Java 6 or newer. This ensures that Kotlin can be used in environments such as Android, where Java 6 is the latest supported version.

Kotlin is an Object-Orientated language. However it has support for higher-order functions as well as lambda expressions and top-level functions. In addition, there are a good number of common functional language constructs in the standard Kotlin library (such as map, flatMap, reduce, etc.). Also, there’s no clear definition on what a Functional Language is so we couldn’t say Kotlin is one.

We believe it makes the code more readable. Besides, it enables some nice syntactic features. For instance, it is easy to leave type annotations out. Scala has also proven pretty well this is not a problem.

At JetBrains, we’ve been developing for the Java platform for a long time, and we know how good it is. On the other hand, we know that the Java programming language has certain limitations and problems that are either impossible or very hard to fix due to backward-compatibility issues. We know that Java is going to stand long, but we believe that the community can benefit from a new statically typed JVM-targeted language free of the legacy trouble and having the features so desperately wanted by the developers.

The main design goals behind this project are

  • To create a Java-compatible language
  • That compiles at least as fast as Java
  • Make it safer than Java, i.e. statically check for common pitfalls such as null pointer dereference
  • Make it more concise than Java by supporting variable type inference, higher-order functions (closures), extension functions, mixins and first-class delegation, etc;
  • And, keeping the useful level of expressiveness (see above), make it way simpler than the most mature competitor – Scala.