Doesn't look very different from the equivalent diagram for Java. Have you seen how many different collection classes and interfaces there are in the Java stand

Doesn't look very different from the equivalent diagram for Java. Have you seen how many different collection classes and interfaces there are in the Java standard libs? AbstractCollection AbstractList AbstractMap AbstractMap.SimpleEntry AbstractMap.SimpleImmutableEntry AbstractQueue AbstractSequentialList AbstractSet ArrayDeque ArrayList Arrays BitSet Collections Dictionary EnumMap EnumSet HashMap HashSet Hashtable IdentityHashMap LinkedHashMap LinkedHashSet LinkedList PriorityQueue Stack TreeMap TreeSet Vector WeakHashMap ArrayBlockingQueue ConcurrentHashMap ConcurrentLinkedDeque ConcurrentLinkedQueue ConcurrentSkipListMap ConcurrentSkipListSet CopyOnWriteArrayList CopyOnWriteArraySet DelayQueue LinkedBlockingDeque LinkedBlockingQueue LinkedTransferQueue PriorityBlockingQueue SynchronousQueue BlockingDeque BlockingQueue ConcurrentMap ConcurrentNavigableMap TransferQueue Collection Deque Iterator List ListIterator Map Map.Entry NavigableMap NavigableSet Queue RandomAccess Set SortedMap SortedSet I've worked with both Java and Scala collections classes for years and I strongly prefer the Scala collections. If you prefer the Java collections they work just fine from Scala too.