[vvillena]

Scala is more strict than D for this use case. In Scala, if you want a function to be available to a certain type as if it was a method call, you need to be explicit about it. You have to declare an "implicit class" that takes the base type as an argument, and define the function as a method of the implicit class. You also need to ensure the implicit class is in scope. Once these conditions are met, you can use it as a method.

    val t1 = MyType()
    def fun(t: MyType, argument: Int) = argument

    // can't do this yet
    // t1.fun(42)
    
    // In Scala 2 you use an implicit class to add methods to a type
    implicit class MyEnrichedType(t: MyType) {
      def fun(argument: Int) = fun(t, argument)
    }

    // In Scala 3 you use an extension
    extension (t: MyType)
      def fun(argument: Int) = fun(t, argument)
    
    // now it can be done
    t.fun(42)

Regarding your question about the stdlib methods being able to be chained: they are not special. They are defined for the type the methods return, so they can be used.

Rejecting all kinds of implicits and then complaining about Scala missing features is a bit unfair. "Implicit"is a single keyword, but not a single feature. Implicit arguments, implicit conversions and implicit classes are not the same thing. Fortunately, Scala 3 will clear this misunderstanding.