Many methods of a program receive as parameter a List[Map[String, String]].
I'd like to formalize it and make it more readable by defining a class such as:
class MyClass extends List[Map[String, String]]
However it throws an error:
Illegal inheritance from sealed class 'List'
Is there a proper way to handle it?
The thing you need is called a type alias:
type MyClass = List[Map[String, String]]
https://alvinalexander.com/scala/scala-type-aliases-syntax-examples
You get the error because you're trying to extend a sealed trait which can be only extended in the same file in which the trait is defined.
https://alvinalexander.com/scala/scala-type-aliases-syntax-examples https://underscore.io/blog/posts/2015/06/02/everything-about-sealed.html
One option is to use composition rather than inheritance:
case class MyClass(value: List[Map[String, String]])
This is more type-safe than using a type alias, as you can only pass an instance of MyClass where MyClass is expected, whereas the type alias approach allows any List[Map[String, String]]. It can also help avoid primitive obsession. Which one you choose depends on your use case.
