Oddbean new post about login | logout @54814b2f So is A: Type mean that metadata is kept around at runtime? Guess I'm asking if you have compile time only type reflection.
@db915dd6 Ah, in this case it's all compile time, Type being an intrinsic. You do have quite powerful compile-time reflection. For one there is ClassTag – this is weaker, but it allows you to create reified Arrays. https://scala-lang.org/api/3.3.1/scala/reflect/ClassTag.html Scala 2.x had TypeTag, with everything, but it was exposing compiler info so it was removed. You can use ClassTag for more depth, like what I did here, e.g.: https://github.com/monix/newtypes/blob/main/core/shared/src/main/scala/monix/newtypes/TypeInfo.scala Or smth like this is probably more complete: https://github.com/zio/izumi-reflect
@54814b2f But it looks like you still need RTTI? Admittedly I don't know much about this part of Scala so I'll investigate further. Thanks!
@db915dd6 ClassTag can give you a Class, which the JVM needs, so yes, that's related to RTTI, but the ClassTag itself is generated by the compiler. I mentioned ClassTag because it's the easiest to use, and you basically get the equivalent of C#'s reification. That library, izumi-reflect, doesn't have anything to do with a RTTI. All type info is exposed in macros, but AFAIK it's no longer easily accessible as a TypeTag, so you have to write a macro to get it 🤷♂️
@db915dd6 BTW, one pretty good development is that you can derive type class instances pretty easily, and you only need "inline" functions with no macros, just compile-time reflection via implicits, which can deconstruct sum and product types.