With scala.meta replacing scala.reflect, what will happen to ClassTags and TypeTags?

Question

Or is this even relevant?

What I have in mind is using the ClassTag or TypeTag annotations, like so:

scala>
import scala.reflect.runtime.universe.TypeTag

def f[T : TypeTag](ls : List[T]) : String = {
  ???
}

results in :

f: [T](ls: List[T])(implicit evidence$1: reflect.runtime.universe.TypeTag[T])String

As you can see, the TypeTag is seen by the compiler which adds an implicit argument. Is there an equivalent in scala.meta ? How will this work, and will there be any changes in the way erasure is handled?

Answer 1

At the moment scala.meta does not provide runtime introspection, however, that's planned for future releases. APIs would be similar to scala.reflect (but in terms of scala.meta , eg different Abstract Syntax Trees , no exposed compiler internals, etc), and I really hope that end user wont see much difference.

So, functionality of ClassTag/TypeTag is not likely to disappear. Most probably, scala.meta will use a bridge ( paradise ) to get access to scalac internals (and that involves scala.reflect ).

Also note that scala.reflect will be supported in scala 2.x branch, but not in dotty .