Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
842 views
in Technique[技术] by (71.8m points)

scala - Combining 2 Options into 1

Is there a predefined function x in Scala that combine 2 Options so that

Some(a) x None => Some(a)
None x Some(b) => Some(b)
None x None => None
See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

Yes, this is the orElse method. It chooses the first defined value, or None if neither is defined.

scala> Some(1) orElse None
res0: Option[Int] = Some(1)

scala> None orElse Some(1)
res1: Option[Int] = Some(1)

scala> None orElse None
res2: Option[Nothing] = None

scala> Some(1) orElse Some(2)
res3: Option[Int] = Some(1)

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...