CODEWITHSUNDEEP
scala
Mandroid
Mandroid

Reputation: 7468

Scala: Expression, Value, Type

I am going through a Scala book, and it states few concepts like:

Expression evaluates to a value
A value a an object
Expression has a type
A value doesn't have a type

Value is an object but it doesn't have a type.

How is it possible? In jvm, objects are of certain type, isn't?

Upvotes: 0

Views: 79

Answers (1)

Alexey Romanov
Alexey Romanov

Reputation: 170713

The distinction here is that objects have a class, but it's not the same as a type. E.g.

val list = List(1, 2, 3)

The type of list is List[Int]; when you run the program, you can see in the debugger (or by calling list.getClass) that its class is something called $colon$colon (which corresponds to :: in Scala code).

 val list2 = List.empty[Int]
 val list3 = List("")

list2 has the same type as list1, but a different class; list3 has a different type, but the same class.

Upvotes: 3

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