val q"def foo(..{$names: $tpes = $defaults})" = q"def foo(x: X, y: Y = Y(0))"
// names    == List(TermName("x"), TermName("y"))
// tpes     == List(tq"X", tq"Y")
// defaults == List(q"", q"Y(0)")

val q"def foo(..$params)" = q"def foo(x: X, y: Y = Y(0))"
val names    = params.map { case q"$_ val $name: $_   = $_"       => name    }
val tpes     = params.map { case q"$_ val $_   : $tpe = $_"       => tpe     }    
val defaults = params.map { case q"$_ val $_   : $_   = $default" => default }