How to find Future implementation in scala.concurrent?

Question

I am trying to understand what exactly happens, when I call

val f = scala.concurrent.Future {... // my body function }

The code of object Future defines apply methods as follows:

def apply[T](body: =>T)(implicit execctx: ExecutionContext): Future[T] =
   impl.Future(body)

Unfortunately I do not see where the impl is defined in the code (and what it exactly does). My question is where the impl is defined.

Answer 1

impl is just a package from which Future object borrows implementation class.

Since Future object lives in the same concurrent package it could address impl package effortlessly (no explicit imports required)