Passing functions for all applicable types around

Question

I followed the advice found here to define a function called square, and then tried to pass it to a function called twice. The functions are defined like this:

Answer 1

Another solution is to lift square into partially applied function:

scala> twice(square(_:Int),2)
res1: Int = 16

This way the implicit is applied to square as in:

scala> twice(square(_:Int)(implicitly[Numeric[Int]]),2)
res3: Int = 16

There is even another approach:

def twice[T:Numeric](f: (T) => T, a: T): T = f(f(a))
scala> twice[Int](square,2)
res1: Int = 16

But again, the type parameter don't get inferred.