Articles:
https://pavelfatin.com/scala-collections-tips-and-tricks/
https://habrahabr.ru/post/333362/

Odersky - Fighting Bit Rot with Types

Scala WAT - collections:
http://habrahabr.ru/company/tcsbank/blog/184310/
http://rickyclarkson.blogspot.ru/2008/01/in-defence-of-0l-in-scala.html

ScalaBlitz:
http://scala-blitz.github.io/
http://www.reddit.com/r/scala/comments/2951es/lightningfast_standard_collections_with/
https://github.com/scala-blitz/scala-blitz

Iterable
- Map
- Set
- Seq
-- InexedSeq
--- Vector
--- Array
--- String
-- LinearSeq
--- List

??? implicit wrappers to behave like ...

common methods:
- map
- flatMap
- filter
- foldLeft
- foldRight

trait Map[Key, Value] extends (Key => Value) ...
trait Seq[Elem] extends (Int => Elem)
    we can write elems(i)