I have a scala file which uses a trait to provide implicit values:
class A
class B
class Service {
def check(implicit a:A, b:B) = println("hello")
}
object Main extends App with Dependencies {
def run() {
val service = new Service
service.check
}
}
trait Dependencies {
implicit val a = new A
implicit val b = new B
}
But it can't be compiled, the error is:
error: could not find implicit value for parameter a: A
service.check
^
But, if I put the trait Dependencies to the beginning of the file:
trait Dependencies {
implicit val a = new A
implicit val b = new B
}
// other code are here
It compiles!
Why we must put it at the beginning?
