Implicit map, or something like that

Here is what I have so far. What I want to achieve is making containers behave like the type they contain.

implicit def transformer[T, A](f: T => A)
    : List[T] => List[A] = 
      t       => t map f

implicit def combiner[T, U, A](f: (T, U) => A)
    : (List[T], List[U]) => List[A] = 
      (t      , u      ) => t zip u map { x => f(x._1, x._2) }

val x = List(1, 2, 3)
val f: Int => Int = (_ + 1)
val fx = f(x) // fx = List(2,3,4)

val g: (Int, Int) => Int = (_ + _)
val gxx = g(x, x) // gxx = List(2,4,6)

Now, this works as I want for functions. But I have a problem with methods. For instance, this will obviously not work :

val double = x + x

This does not work, because + has to be a method of List[Int], which it is not.

I would need to extract the method name, see if there is a function in scope with that name that can be applied to the underlying type, and then lift it with the implicit definition.

Or maybe that can be done with a type constructor that would somehow scan the underlying type on instanciation, and define the right methods.

Both are quite ugly solutions, and I am not even sure they are feasible. Is there any other way to achieve what I want, that doesn't involve writing explicitely all methods ?


Have you had a look at Dynamics? In combination with standard Java Reflection, this might solve your problem. I don't know if Content Assist in IDE's get's confused by this, though...

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