The PAL (Platform Abstraction Layer I assume) is just the stdlib that is provided. The stdlib is not the same for all platforms, as can be seen in the documenta

The PAL (Platform Abstraction Layer I assume) is just the stdlib that is provided. The stdlib is not the same for all platforms, as can be seen in the documentation. A regex implementation is provided for all platforms, but is not quite the same on all platforms: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.text/-regex/ https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.text/-r... In shared code you can define interfaces that have to be implemented by any platform you use.