An alternative desugaring for implicit case classes (kudos to @Toxaris!).

Foo.scala

scala> :paste
// Entering paste mode (ctrl-D to finish)

class Foo(bar: Int)

implicit object Foo extends (Int => Foo) {
  def apply(bar: Int) = new Foo(bar)
}

// Exiting paste mode, now interpreting.

defined class Foo
defined module Foo

scala> def bar(a: Foo) = a
bar: (a: Foo)Foo

scala> bar(1)
res0: Foo = Foo@3e91cc3a

scala> bar(Foo(1))
res1: Foo = Foo@44fc63be

It turns out that this was already discussed on the ML, and turned down for unclear reasons.