Is it possible to specify type parameters for String Interpolation in Scala

Question

implicit class Interpolator(val a: StringContext) extends AnyVal {
  def foo[A](args: Any*): A = ???
}

val first  = foo[String]"myString" // This does not parse
val second = (new StringContext).foo[String]("myString") // This works but I'm wondering if there is a more concise syntax
val third = foo"myString"[String] // This one is intriguing because it parses but the compiler outputs "method foo does not take type parameters"... what?

If A can be inferred then it's all good because foo"myString" will simply work but if it can't I am wondering if there is a better syntax than second that allows me to specify the type parameter I expect.

Answer 1

Second only compile but it doesn't really work, we can try for example

implicit class Interpolator(val a: StringContext) {
    def foo[A](args: Any*): A = args.head.asInstanceOf[A]
}

val a = 2
val second = (new StringContext)foo[String]"a=$a"
println(second)// this will print a=$a which is not the expected output

But the following should work

implicit class Interpolator[A](val a: StringContext)  {
    def foo(args: Any*): A = args.head.asInstanceOf[A]
}

val a = 2
val first :Int = foo"a=$a" // : Int is what that does the trick
println(first) // will print 2 as expected