Question

I’m looking for a collect method in scala 2.7 but I can’t seem to find an applicable call. Is there something equivalent to collect that I can use in scala?

To be clear I’m looking to filter elements from a list and map those filtered to a new type.

Answer 1

You can use flatMap (the full method signature in 2.7 is def flatMap[B](f : (A) => Iterable[B]) : List[B] ). It is declared on both Iterable and Iterator (with slightly different signatures):

scala> val l = List("1", "Hello", "2")
l: List[java.lang.String] = List(1, Hello, 2)

scala> val ints = l.flatMap { s => try { Some(s.toInt) } catch { case _ => None } }
ints: List[Int] = List(1, 2)

In the above example I’m taking advantage of an explicit conversion option2iterable in Predef. It’s declared in 2.8 on TraversableLike:

def flatMap[B, That](f: A => Traversable[B])(implicit bf: CanBuildFrom[Repr, B, That]): That