Kotlin (programming language) facts for kids
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| Paradigm | Multi-paradigm: object-oriented, functional, imperative, block structured, declarative, generic, reflective, concurrent |
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| Designed by | JetBrains |
| Developer | JetBrains |
| First appeared | July 22, 2011 |
| Stable release |
1.9.0
 / 6 July 2023 |
| Typing discipline | Inferred, static, strong |
| Platform |
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| OS | Cross-platform |
| License | Apache License 2.0 |
| Filename extensions | .kt, .kts |
| Influenced by | |
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Kotlin is a cross-platform, statically typed, general-purpose high-level programming language with type inference. Kotlin is designed to interoperate fully with Java, and the JVM version of Kotlin's standard library depends on the Java Class Library,
but type inference allows its syntax to be more concise. Kotlin mainly targets the JVM, but also compiles to JavaScript (e.g., for frontend web applications using React) or native code via LLVM (e.g., for native iOS apps sharing business logic with Android apps). Language development costs are borne by JetBrains, while the Kotlin Foundation protects the Kotlin trademark.
On 7 May 2019, Google announced that the Kotlin programming language was now its preferred language for Android app developers. Since the release of Android Studio 3.0 in October 2017, Kotlin has been included as an alternative to the standard Java compiler. The Android Kotlin compiler produces Java 8 bytecode by default (which runs in any later JVM), but lets the programmer choose to target Java 9 up to 20, for optimization, or allows for more features; has bidirectional record class interoperability support for JVM, introduced in Java 16, considered stable as of Kotlin 1.5.
Kotlin has support for the web with Kotlin/JS, either through a classic interpreter-based backend which has been declared stable since version 1.3, or an intermediate representation-based backend which has been declared stable since version 1.8. Kotlin/Native (for e.g. Apple silicon support) is considered beta since version 1.3.
Example
Here is an example of a hello world program in Kotlin.
// Hello World Program
fun main(args : Array<String>) {
println("Hello world!")
}Adoption
In 2018, Kotlin was the fastest growing language on GitHub, with 2.6 times more developers compared to 2017. It is the fourth most loved programming language according to the 2020 Stack Overflow Developer Survey.
Kotlin was also awarded the O'Reilly Open Source Software Conference Breakout Award for 2019.
Many companies / organizations have used Kotlin for backend development:
- Allegro
- Amazon
- Cash App
- Flux
- Gradle
- JetBrains
- Meshcloud
- Norwegian Tax Administration
- OLX
- Pivotal
- Rocket Travel
- Shazam
- Zalando
Some companies / organizations have used Kotlin for web development:
- Barclay's Bank
- Data2viz
- Fritz2
- JetBrains
A number of companies have publicly stated they were using Kotlin:
- Basecamp
- Corda, a distributed ledger developed by a consortium of well-known banks (such as Goldman Sachs, Wells Fargo, J.P. Morgan, Deutsche Bank, UBS, HSBC, BNP Paribas, and Société Générale), has over 90% Kotlin code in its codebase.
- Coursera
- DripStat
- Duolingo
- Netflix
- Trello
- Uber
