Kotlin Collection Operator- Rolling Batches and Rolling Occurences

rolling_batches_occurrences.kt

fun <T> List<T>.rollingBatches(batchSize: Int) = (0..size).asSequence().map { i ->
    subList(i, (i + batchSize).let { if (it > size) size else it })
}.filter { it.size == batchSize }

enum class RecurrenceMode { PARTIAL_ONLY, FULL_ONLY, ALL }

fun <T> List<T>.rollingRecurrences(slotsNeeded: Int, gap: Int, recurrences: Int, mode: RecurrenceMode = RecurrenceMode.FULL_ONLY) =
        (0..size).asSequence().map { i ->
            (1..recurrences).asSequence().map { (it - 1) * gap }
                    .filter { it + i < size}
                    .map { r ->
                        subList(i + r, (i + r + slotsNeeded).let { if (it > size) size else it })
                    }
                    .toList()
        }.filter {
            when (mode) {
                RecurrenceMode.ALL -> true
                RecurrenceMode.FULL_ONLY -> it.size == recurrences && it.all { it.size == slotsNeeded }
                RecurrenceMode.PARTIAL_ONLY -> it.size < recurrences || it.any { it.size < slotsNeeded }
            }
        }