Kotlin command-line compiler

1. Create a simple console JVM application in Kotlin that displays "Hello, World!". In a code editor, create a new file called hello.kt with the following code:

   fun main() {
       println("Hello, World!")
   }

2. Compile the application using the Kotlin compiler:

   kotlinc hello.kt -include-runtime -d hello.jar

   • The -d option indicates the output path for generated class files, which may be either a directory or a .jar file.

   • The -include-runtime option makes the resulting .jar file self-contained and runnable by including the Kotlin runtime library in it.

   To see all available options, run:

   kotlinc -help

3. Run the application:

   java -jar hello.jar

If you're developing a library to be used by other Kotlin applications, you can build the .jar file without including the Kotlin runtime:

kotlinc hello.kt -d hello.jar

Since binaries compiled this way depend on the Kotlin runtime, you should ensure that it is present in the classpath whenever your compiled library is used

You can also use the kotlin script to run binaries produced by the Kotlin compiler:

kotlin -classpath hello.jar HelloKt

HelloKt is the main class name that the Kotlin compiler generates for the file named hello.kt.

You can run the compiler without parameters to have an interactive shell. In this shell, you can type any valid Kotlin code and see the results.

You can use Kotlin as a scripting language. A Kotlin script is a Kotlin source file (.kts) with top-level executable code.

import java.io.File

// Get the passed in path, i.e. "-d some/path" or use the current path.
val path = if (args.contains("-d")) args[1 + args.indexOf("-d")]
           else "."

val folders = File(path).listFiles { file -> file.isDirectory() }
folders?.forEach { folder -> println(folder) }

To run a script, pass the -script option to the compiler with the corresponding script file:

kotlinc -script list_folders.kts -- -d <path_to_folder_to_inspect>

Kotlin provides experimental support for script customization, such as adding external properties, providing static or dynamic dependencies, and so on. Customizations are defined by so-called script definitions – annotated kotlin classes with the appropriate support code. The script filename extension is used to select the appropriate definition. Learn more about Kotlin custom scripting.

Properly prepared script definitions are detected and applied automatically when the appropriate jars are included in the compilation classpath. Alternatively, you can specify definitions manually by passing the -script-templates option to the compiler:

kotlinc -script-templates org.example.CustomScriptDefinition -script custom.script1.kts

For additional details, see the KEEP-75.