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scalascalazscala-catsmap-functioneither

Scala - Is there a function to map Seq[A] => Seq[Either[Throwable, B]]?

I am looking for a function that will map over a collection coll: Seq[A] while applying a function f: A => B and returning a Seq[Either[Throwable, B]] so that errors can be handled downstream.

Is there a function similar to this that is pre-baked into some library? Perhaps Cats or Scalaz?

See my implementation below:

import cats.syntax.either._

def eitherMap[A,B](f: A => B, coll: Seq[A]): Seq[Either[Throwable, B]] = {
  coll.map { elem => 
      Either.catchNonFatal(f(elem))
  }
}
Solution

  • Per jwvh: coll.map(a => Try(f(a)).toEither) seems to be the simplest/cleanest way to accomplish this.