I tried making a polymorphic identity function in Scala 3:  val f = [T] => (x: T) => x  I can now apply it to itself (f(f)), but only once. f(f)(f) gives me the following error:  exception while typing f.apply[(f : Function1)](f).apply of class class dotty.tools.dotc.ast.Trees$Select # -1 exception while typing f.apply[(f : Function1)](f).apply[(f : Function1)] of class class dotty.tools.dotc.ast.Trees$TypeApply # -1 exception while typing f.apply[(f : Function1)](f).apply[(f : Function1)](f) of...