Question

Or are vals in scala objects lazy by default?

Anyway, if it’s necessary to declare a val in an object lazy by using lazy, is it possible to do something like

lazy object SomeObject

or (like you do in c++)

object A {
lazy:
    val a
    val b
    ...
}

Because I would like to be lazy and not have to relabel all my vals lazy val

Answer 1

To answer your first question (“are vals in scala objects lazy by default?”): No, not exactly, but the objects themselves are kind of lazy, which may be lazy enough. From 5.4 (“Object Definitions”) of the Scala language specification:

Note that the value defined by an object definition is instantiated
lazily. The new m$cls constructor is evaluated not at the point of
the object definition, but is instead evaluated the first time m is
dereferenced during execution of the program (which might be never at
all).

So, for example, if we have these three objects:

object X {
  val answer = { println("Here's X's answer!"); 42 }
}

object Y {
  lazy val answer = { println("Here's Y's answer!"); 1 }
}

object Z extends App {
  println("Here we go.")
  println(X)
  println(Y)
  println(X.answer)
  println(Y.answer)
}

Then when we run Z, we see the following:

Here we go.
Here's X's answer!
X$@38d24866
Y$@f1aa6ce
42
Here's Y's answer!
1

So the val in X isn’t lazy, but it’s also not evaluated until the first time we use X.