Run Kotlin REPL with built source code and main classpath in Gradle

build.gradle.kts

// Assuming Kotlin plugin is applied...

// Run as: ./gradlew kotlinRepl --console plain --no-daemon
val kotlinRepl by tasks.creating {
  dependsOn("assemble")
  doFirst {
    val buildscriptClasspath = rootProject.buildscript.configurations["classpath"]

    val embeddedableCompiler = buildscriptClasspath
      .resolvedConfiguration
      .resolvedArtifacts
      .first { it.name == "kotlin-compiler-embeddable" }
    val jarLocation = embeddedableCompiler.file

    val mainClasspath = java.sourceSets["main"].runtimeClasspath.joinToString(separator = ":")
    javaexec {
      classpath = files(jarLocation)
      main = "org.jetbrains.kotlin.cli.jvm.K2JVMCompiler"
      standardInput = System.`in`
      args("-cp", mainClasspath)
    }
  }
}