What does the `#` operator mean in Scala?

I see this code in this blog: Type-Level Programming in Scala: // define the abstract types and bounds trait Recurse { type Next <: Recurse // this is the recursive function definition type X[R <: Recurse] <: Int } // implementation trait RecurseA extends Recurse { type Next = RecurseA // this is the implementation type X[R <: Recurse] = R#X[R#Next] } object Recurse { // infinite loop type C = Rec

[yoyama]

“Now, # makes it possible for you to refer ”