没有证据的证据

Question

Is there a Not[Ev] type, or a way to implement it, that I can use in the following way

def someMethod[X,Y](implicit ev:Not[X <:< Option[Y])= ???

Meaning the type X is not an Option[_] type? (and more could be done with that)

Answer 1

Docs of implicitAmbiguous suggest the following implementation of type inequality

trait =!=[C, D]

implicit def neq[E, F] : E =!= F = null

@annotation.implicitAmbiguous("Could not prove ${J} =!= ${J}")
implicit def neqAmbig1[G, H, J] : J =!= J = null
implicit def neqAmbig2[I] : I =!= I = null

where

def someMethod[X,Y](implicit ev: X =!= Option[Y])= ???

someMethod[Int, String]       // ok
someMethod[Option[Int], Int]  // error