Implicit Parameters

Implicit Parameters

An implicit parameter lets the compiler automatically supply an argument from an in-scope implicit val/def, if the caller doesn't provide one explicitly. This is commonly used for passing along contextual configuration, like a formatting rule or execution context, without threading it explicitly through every call. Only one implicit value of a given type can be in scope at a time without ambiguity errors.

Note: If the compiler reports 'could not find implicit value', it means no matching implicit definition is in scope for that parameter's type.

Example: Implicit Parameters

object Main extends App {
  implicit val defaultGreeting: String = "Hello"

  def greet(name: String)(implicit greeting: String): Unit = {
    println(s"$greeting, $name!")
  }

  greet("Alice") // uses the implicit defaultGreeting
  greet("Bob")("Hi") // explicitly overridden
}