import scala.reflect.mirror._ object Test extends App { def foo[T](ys: List[T]): Int => Int = { val fun = reify{(x: Int) => { x }} val toolbox = mkToolBox() val dyn = toolbox.runExpr(fun.tree) dyn.asInstanceOf[Int => Int] } println(foo(List(1, 2, 3))(10)) println(foo(List(1, 2, 3, 4))(10)) }