tuple-filter.scala

import scala.compiletime.ops.int.<

type P[x] <: Boolean = x match {
  case 3 => false
  case _ => true
}

type RejectAll[x] = false

type Pos[X <: Int] = 0 < X

def Test =
  summon[Tuple.Filter[(1, 2, 3, 4), P] =:= (1, 2, 4)]
  summon[Tuple.Filter[(1, 2, 3, 4), RejectAll] =:= EmptyTuple]
  summon[Tuple.Filter[EmptyTuple, P] =:= EmptyTuple]
  summon[Tuple.Filter[(1, -2, 3, -4), Pos] =:= (1, 3)]