Publisher's Synopsis
Kotlin is the new lovechild of the JVM developers' world.Google promoted Kotlin as a first class language on its Java-based Android platform back in May. Since then, the whole development world has been wondering: what is this language? Kotlin has been around for a few years and has been running on production systems, after the languages 1.0 release in February 2016, for a year or so. The language has received a lot of praise and loving words from the developer community. It is a breath of fresh air, a good upgrade to systems running older versions of Java, and still somehow an old dog in a familiar playing field.What is Kotlin? What does it bring that the JVM doesn't already have?Kotlin vs. JavaThere are a few approaches we can take when introducing Kotlin. We can discuss it through Java, the language Kotlin needs to be based on due to its JVM runtime, or we can do it through Scala, the language Kotlin is heavily influenced by. There is no doubt that Kotlin is better than Java. It is much safer and more concise. It provides you with a bunch of additions to your standard Java language and enhances a few bits and pieces that Java developers have grown to dislike. Additions include things like null safety, extension functions, data classes, objects, first class functions as well as extensive and expressive lambdas. Kotlin also enhances Java's type inference and type system and takes massive leaps forward with collections.Kotlin vs. ScalaPerhaps, it's better to compare Kotlin against Scala. This comparison might scare some of you quite a bit because Scala has the reputation of being simultaneously intriguing and frightening. It heavily introduces functional programming paradigm to you while still mixing it into familiar object orientation (hence in an awfully lot of cases creating a mishmash of advanced techniques from both paradigms), brings in some new build tools, and gives your internal flow state a frustrating break every now and then due to long compile times.I come bearing both good news and bad news. Let's start with the bad news: Bad news is that Kotlin is similar to Scala, it follows the same path as Scala doesThe good news: luckily, it's only slightly similar to Scala in every aspect.Kotlin & Functional Programming ParadigmThe functional programming paradigm is big part of Kotlin as well. Luckily, it doesn't go into the higher-kinded types, monadic do-continuations, or advanced type theory concepts that make you seek out Bartosz Milewski and his brilliant book on Category Theory. Kotlin introduces easy-to-use collection manipulation functions and functional pipelines for you. You will get your maps, filters, and folds, which in most cases are enough to get to the functional programming path.Java devs that have been lucky enough to jump into Java 8 (hugs and kisses to you Android and/or enterprise developers) will be familiar with the these basics and will feel right at home when they jump into Kotlin. They will also find conciseness and safety of better type system, which will spark their first crush towards the language. It is just so pretty and seamless to pipe these functions together and build a clean pipeline. And when you come back to it after a few weeks, you'll still feel like you can somewhat understand it. Smiles all around.
