How do I compare two durations and find the shorter one using coalescing?

  shortBreak <- PT15M       15 minutes
  longBreak <- PT1H         1 hour
  halfDay <- PT4H30M        4 hours 30 minutes
  threeDays <- P3D          3 days

  if shortBreak < longBreak     shorter duration
  ordering <- shortBreak <=> longBreak

  shorter <- shortBreak <? longBreak   returns the shorter duration
  longer <- shortBreak >? longBreak    returns the longer duration

defines module qa.operators.durationops

  defines function

    shorterOf() as pure
      ->
        left as Duration
        right as Duration
      <- rtn as Duration: left <? right

    longerOf() as pure
      ->
        left as Duration
        right as Duration
      <- rtn as Duration: left >? right

  defines program

    DurationOpsDemo()
      stdout <- Stdout()

      // === DURATION LITERALS (ISO 8601) ===

      shortBreak <- PT15M
      longBreak <- PT1H
      halfDay <- PT4H30M

      // === COMPARISON ===

      if shortBreak < longBreak
        stdout.println("Short break is shorter than long break")

      require shortBreak < longBreak
      require longBreak > shortBreak
      require shortBreak <> longBreak

      // === SPACESHIP ORDERING ===

      ordering <- shortBreak <=> longBreak
      stdout.println(`Short <=> Long: ${ordering}`)
      require ordering < 0

      // === COALESCING: FIND SHORTER AND LONGER ===

      shorter <- shorterOf(shortBreak, longBreak)
      longer <- longerOf(shortBreak, longBreak)
      stdout.println(`Shorter: ${shorter}`)
      stdout.println(`Longer: ${longer}`)
      require shorter == shortBreak
      require longer == longBreak

      // === HALF DAY COMPARISON ===

      require halfDay > longBreak
      require halfDay < PT5H
      stdout.println(`Half day: ${halfDay}`)

      // === STRING AND ISSET ===

      durStr <- $shortBreak
      stdout.println(`Duration string: ${durStr}`)
      require shortBreak?

      unsetDuration <- Duration()
      require ~unsetDuration?

left.min(right)

left <? right