scala-implicits

I am struggling on how to create an instance of Functor[Dataset] ... the problem is that when you map from A to B the Encoder[B] must be in the implicit scope but I am not sure how to do it. implicit val datasetFunctor: Functor[Dataset] = new Functor[Dataset] { override def map[A, B](fa: Dataset[A])(f: A => B): Dataset[B] = fa.map(f) } Of course this code is throwing a compilation error since Encoder[B] is not available but I can't add Encoder[B] as an implicit parameter because it would change the map method signature, how can I solve this? You cannot apply f right away, because you are

Intellij falsely marked some import of Scala implicits as not being use. Is there a way to prevent it from deleting those import when optimized them explicitly for a specific import and not prevent optimized import for the entire project ? I'm afraid there isn't, I had similar issues especially when using akka and importing the implicit execution context from an ActorSystem in some cases. I recommend defining the value instead of importing. One such example would be: // Avoid importing the execution context like this class MyActor extends Actor { import context.system.dispatcher } // Define it

To reduce compile times of my project, I'm caching certain type classes that are resolved by implicit lookups. This appears somewhat cumbersome though, because the straight forward implementation does not work: scala> implicit val x: String = implicitly[String] x: String = null The implicit lookup considers its own, uninitialized definition as a valid implementation. A lazy val would blow the stack with infinite recursion. Therefore I'm currently handling it in this fashion: implicit val x: String = cache.x object cache { val x: String = implicitly[String] } But this makes it overly