I created a trait with the following signature and methods (details are omitted):
trait Cachable[A <: java.io.Serializable] {
def push(key: String, value: A) = ???
def pull(key: String): A = ???
}
The following code does not compile (Document class implements java.io.Serializable, and List implements scala.Serializable which extends java.io.Serializable):
class DocsService extends Cachable[List[Document]] {
...
}
The error message said something like: Cachable[List[Document]] does not conform with type Cachable[A <: java.io.Serializable].
If I understand the issue correctly, the compiler means that Cachable[scala.Serializable] is not a subtype of Cachable[java.io.Serializable].
I thought, <: statement is similar to java's ? extends statement, which would fix this type of problem in Java.
How to fix it in Scala?
