optional parameters in Scala that are not a pain to write

params.scala

import scala.language.implicitConversions

case class Optional[+T](value: Option[T])

val omit = Optional(None)

implicit def valueToOptional[T](value: T): Optional[T] = Optional(Some(value))
implicit def optionalToOption[T](opt: Optional[T]): Option[T] = opt.value

def add(a: Int, b: Optional[Int] = omit, c: Optional[Int] = omit): Int =
  a + b.getOrElse(0) + c.getOrElse(0)

println(add(42))

println(add(42, 1))

println(add(42, 2, 3))

// as opposed to

def add2(a: Int, b: Option[Int] = None, c: Option[Int] = None): Int =
  a + b.getOrElse(0) + c.getOrElse(0)

println(add2(42))

println(add2(42, Some(1)))

println(add2(42, Some(2), Some(3)))

// Yeah, yeah I know. Not the best example as in this case you could just write the default values directly
// into the argument list as shown in the following, but you get the idea. I mean there are cases were
// there simply is no default value.

def add3(a: Int, b: Int = 0, c: Int = 0): Int = a + b + c