gistfile1.java

// This type is defined in some other library we can't modify
class SomeObject(val a: Int, val b: String) {
    def c = "a = " + a + ", b = " + b
}

// This is our code
object DynamicDemo {
    // A function which takes anything which has a member 'a' of type Int and a
    // member 'd' of type String
    def f(arg: {def a: Int; def d: String}) = "f says: " + arg.a + " " + arg.d

    // Testing function
    def main(args: Array[String]): Unit = {
        println("Test 1")
        // We can create a 
        val r1 = f(new {val a = 123; val d = "456"})
        println(r1)

        println("Test 2")
        val o = new SomeObject(789, "987")
        // Notice we can just pass a SomeObject instance to f!
        val r2 = f(o)
        println(r2)
    }

    implicit def someObjectToFArg(o: SomeObject):
        {def a: Int; def d: String} = new {val a = o.a; val d = o.c}
}