Kotlin’s decision to make every exception runtime is the main reason I don’t use Kotlin. It’s especially baffling that they realized the issue with implicit nullability and got rid of it (though not with Java methods, which opens another can of worms), then went and intoduced implicit “exceptionality”.

The correct way to deal with Java’s checked exceptions would have been introducing a Result type, or, preferably, type algebra, like in TypeScript, so something like:

  fun openFile(fileName: String): File | FileNotFoundException {…}

Then you could handle it similarly to null:

  val content: String | FileNotFoundException = openFile(“myfile.txt”).?read()
  …then you have to do a check before you use content as a String…

or

  val content: String = openFile(“myfile.txt”)?.read() ?: “File not found”

(There could also be other possible ways of handling the exception, like return on exception, jump to a handling block, and so on.)

In fact, null should be treated as an exceptional value the same way all exceptions should be.