CODEWITHSUNDEEP
scalafunctional-programmingscala-collections
Bartłomiej Szałach
Bartłomiej Szałach

Reputation: 2453

Convert List[A] to List[Option[A]] depending on A members

I have defined:

final case class EventOpt(start: Option[Long], end: Option[Long])
final case class Event(start: Long, end: Long)

The only interesting objects for me are those with both fields set and I want to filter the rest

Having List[EventOpt] I'd like to convert it to List[Option[Event]] using Some(Event) when both start and end are set and None when either of start and end them is None?

Eg.

List(EventOpt(Some(1), None), EventOpt(None, Some(2)), EventOpt(Some(3), Some(4))) 
=>
List(None, None, Some(Event(4, 3)))

By doing so, it will allow be to do a simple flatMap over the last list and omit the Nones

Upvotes: 2

Views: 38

Answers (1)

Andrey Tyukin
Andrey Tyukin

Reputation: 44908

You don't need a separate flatMap step, simply collect only what you need right away:

eventOpts.collect { case EventOpt(Some(x), Some(y)) => Event(x, y) }

Upvotes: 6

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