Change Either subclasses type parameters?

[LPTK]

See:

Pre-SIP: Proposal of introducing a Rust-like type "Result"

Suppose we want to implement a function that checks whether the length of a string is within certain limits. If the check succeeds the function shall return the provided value, if it fails some information about the reason shall be returned. We can meet these requirements by using Either as the return type of the function: import scala.util.{Either, Left, Right} def checkString(value: String): Either[String, String] = { val len = value match { case s: String => s.length case _ …