minOfOrNull

Returns the smallest value among all values produced by selector function applied to each element in the sequence or null if the sequence is empty.

inline fun <T> Sequence<T>.minOfOrNull(selector: (T) -> Double): Double?(source)

data class Person(val name: String, val salary: Double)

val people = listOf(
    Person("Alice", 5000.0),
    Person("Bob", 3500.0),
    Person("Charlie", 4500.0)
)

val lowestSalary: Double? = people.asSequence()
    .minOfOrNull { it.salary }

println("Lowest salary: $lowestSalary")

Source