Kotlin

Hadihariri.com

Design

. Java interoperable

. Fast as java

. Concise: without ceremony. Concentrate on value!

. Tooling

http://kotlin.jetbrains.org/

You can build app with any app. The point how many restrictions and frictions the language bring in. 

. Kotlin can target java or JavaScript 

. String interpolation

. Mutable and immutable (val) variable.

. No ; (optional)

. Have functions and classes and traits

. Just one constructor: use optional parameters

. Data classes: a DTO or a class with data and not behavior 

.. Out of the box toString, equal and compare methods

. Delegation is the dependency injection in kotlin

. Too many dependencies on a class it's a sign that the class is doing too much. You may miss an abstraction level.

. Naming is important. Do't use and on naming because it means the class or function is making different things

. Lambda expressions (function literals)

. Inheritance: everything is final unless you write open. The class must then be designed for inheritance

. Type inference

. High order functions

. Singleton objects

. Classes can e extend from trait, open classes or abstract classes

. Null protection: Save operator for java. In kotlin you can't get a nullpoinrtexception (unless you used !!)

. You don't cast, use is operator

. Conventions to override operators

. Sometime you can omit brackets: you can create (Static typed) dsl like in order to be more expressive

. Spek testing library : test business specification! Nice!!!!

. You can call from/to java : completely interoperable on the same project

. Scripting

. Module coming soon

. Vet.x kotlin available https://github.com/alextkachman/vertex-kotlin

Designed to enforce good design practices in real world apps.