Min/max with Option[T] for possibly empty Seq?

Solution 1:

seq.reduceOption(_ min _)

does what you want?

Edit: Here's an example incorporating your _.something:

case class Foo(a: Int, b: Int)
val seq = Seq(Foo(1,1),Foo(2,0),Foo(0,3))
val ord = Ordering.by((_: Foo).b)
seq.reduceOption(ord.min)  //Option[Foo] = Some(Foo(2,0))

or, as generic method:

def minOptionBy[A, B: Ordering](seq: Seq[A])(f: A => B) = 
  seq reduceOption Ordering.by(f).min

which you could invoke with minOptionBy(seq)(_.something)

Solution 2:

Starting Scala 2.13, minByOption/maxByOption is now part of the standard library and returns None if the sequence is empty:

seq.minByOption(_.something)

List((3, 'a'), (1, 'b'), (5, 'c')).minByOption(_._1) // Option[(Int, Char)] = Some((1,b))
List[(Int, Char)]().minByOption(_._1)                // Option[(Int, Char)] = None