Expose constructors for interval types

[LaurenceWarne]

Hi! I'd like to use intervals for which I know for example are only going to be of type [a, ∞), but using the constructor Interval.atOrAbove returns an Interval rather than an Above instance, so the ability to extract the lower bound as an exact ValueBound using x.lowerBound is lost AFAICS.

I think changing the return types would break binary compatibility, so this PR adds new methods on the companion which are in turn called by the corresponding methods on Interval, specifically for:

• Above
• Below
• All
• Empty

I think the constructors for these objects were leaked before, and included the internal flags value, and in general I'm not sure how much the Above, Below, etc are intended for general usage, but let me know any thoughts anyway 🙂

Thanks!

[armanbilge]

Thanks for the PR!

I think changing the return types would break binary compatibility

Actually I think we can do this without breaking compatibility. Instead of changing the return type, add a new method of the same name with the desired return type. Meanwhile, make the old method private and add a dummy type parameter to disambiguate e.g.

object Foo {
  // old
  private[Foo] def bar[DummyParameter](x: Int): AnyRef = ???
  // new
  def bar(x: Int): String = ???
}

[LaurenceWarne]

Actually I think we can do this without breaking compatibility. Instead of changing the return type, add a new method of the same name with the desired return type. Meanwhile, make the old method private and add a dummy type parameter to disambiguate e.g.

Nice! Though I find sbt mimaReportBinaryIssues still doesn't seem to like it: https://github.com/typelevel/spire/actions/runs/8364280484/job/22899223855?pr=1325#step:15:33?