Existential types
def foo(l: List[Option[_]]) = ...
Higher kinded type parameters
case class A[K[_],T](a: K[T])
Ignored variables
val _ = 5
Ignored parameters
List(1, 2, 3) foreach { _ => println("Hi") }
Ignored names of self types
trait MySeq { _: Seq[_] => }
Wildcard patterns
Some(5) match { case Some(_) => println("Yes") }
Wildcard patterns in interpolations
"abc" match { case s"a$_c" => }
Sequence wildcard in patterns
C(1, 2, 3) match { case C(vs @ _*) => vs.foreach(f(_)) }
Wildcard imports
import java.util._
Hiding imports
import java.util.{ArrayList => _, _}
Joining letters to operators
def bang_!(x: Int) = 5
Assignment operators
def foo_=(x: Int) { ... }
Placeholder syntax
List(1, 2, 3) map (_ + 2)
Method values
List(1, 2, 3) foreach println _
Converting call-by-name parameters to functions
def toFunction(callByName: => Int): () => Int = callByName _
Default initializer
var x: String = _ // unloved syntax may be eliminated
