在Scala中进行一系列flatMap的惯用方式是什么？

Question

I know that a for yield is converted to a series of flatMaps followed by a final map. I find myself frequently wanting it to end instead in a final flatMap. My workaround so far has been to do a for yield followed by a flatten like the following:

val aOpt = Some("a")
val bOpt = Some("b")
def fakeComplexFunc(s1: String, s2: String): Option[String] = Some(s1 + s2)
(for {
    a <- aOpt
    b <- bOpt
} yield {
    // Pretend this is a long block with lots of stuff in it
    fakeComplexFunc(a, b)
}).flatten

Is there a better way to do this? Is there any sort of best practice for cases like this? Have I done something drastically wrong if I end up in this situation?

Answer 1

You could bind the result of fakeComplexFunc and yield it:

for {
  a <- aOpt
  b <- bOpt
  c <- fakeComplexFunc(a, b)
} yield c