An Interval[I] typeclass that, given an implementation of the methods start
, end and an ordering of the base bound type, provides default implementation
for common interval-like operations (contains, overlap , gap, etc).
Optional bounds are supported.
Given an Ordering[B], instances are provided for
(B, B)(Option[B], B)(B, Option[B])(Option[B], Option[B])
In the optional bound cases, None represents the minimum value in start
position or the maximum value in end position.
Working with time:
import com.github.tnielens.intervalops.Interval.Ops
import java.time.Instant
implicit val instanctOrdering: Ordering[Instant] = Ordering.fromLessThan(_.isBefore(_))
val Seq(t0, t1, t2, t3) = Seq.iterate(Instant.now(), 4)(_.plusSeconds(5))
assert(((t0, t3) overlap (t1, t2)) == (t1, t2))
assert(((t0, t3) diff (t1, t2)) == (Option((t0, t1)), Option((t2, t3))))Interval works for any base boundary type B given an Ordering[B].
Instances for primitive types (Ordering[Int], Ordering[Double], etc) are
provided by the std library.
import com.github.tnielens.intervalops.Interval.Ops
assert(((0, 10) overlap (5, 15)) == (5, 10))
assert(((0, 10) diff (6, 7)) == (Option((0, 6), Option((7, 10))))Working with optional bounds:
import com.github.tnielens.intervalops.Interval.Ops
assert(((0, Option(10)) overlap (8, None)) == (8, Option(10)))
assert(((0, None: Option[Int]) diff (6, Some(7))) == (Option((0, Some(6)), Option((7, None)))))Mind that Ordering[T] is not contravariant, so you have to upcast Some
and None first operand values to Option for Interval.Ops to work properly.
import com.github.tnielens.intervalops.Interval
import com.github.tnielens.intervalops.Interval.Ops
case class CustomInterval[B](start: B, end: B)
// if possible, put the instance definition in the companion object
// of the `CustomInterval` to avoid the import tax
implicit def customIntervalInst[B](implicit ob: Ordering[B]) =
Interval.instance[CustomInterval[B], B, Bound[B], Bound[B]](
c => Bound(c.start),
c => Bound(c.end),
(b1, b2) => CustomInterval(b1.v, b2.v)
)
assert(CustomInterval(1, 6) contains 5)For cases involving optional bounds, see tuples instances in the companion
object Interval.