如何声明 arguments 并将其传递给 Scala 3 中的隐式参数？

Question

I have this code in scala 2

val number = 20

def double(implicit y:Int)={
  y*2
}

def count(implicit x:Int)={
  double
}

object HelloWorld {
  def main(args: Array[String]): Unit = {
    println(count(number)) // res: 40
  }
}

Here x parameter of count function is annotated as implicit so it is able to be passed into the double function implicitly. How can I do this in Scala 3 using given-using / summon?

Answer 1

The relevant docs section is Relationship with Scala 2 Implicits - using clauses which explains

Explicit arguments to parameters of using clauses must be written using (using...) , mirroring the definition syntax.

So definitions

def double(using y: Int) = y*2
def count(using x: Int) = double

can be applied like so

count(using number)

Note how conceptually the same keyword using is meant to convey both the idea of "requirement" at the definition-site and the idea of "provision" at the call-site.