What is the basic collection type in Scala?

Or in other words what is the equivalent of C# IEnumerable<开发者_JAVA百科T> in Scala? I thought it is Seq[T], but I already found out, that HashMap does not implement this, so it cannot be true.

So, what is it?

Traversable and Iterable are base traits for scala collections. Actually, Iterable extends Traversable.

From scala api doc for Iterable:

A base trait for iterable collections.

This is a base trait for all Scala collections that define an iterator method to step through one-by-one the collection's elements.

And Traversable:

This is a base trait of all kinds of Scala collections. It implements the behavior common to all collections, in terms of a method foreach.

Here is a nice pics from scala-lang site that represents scala collections hierarchy (mutable and immutable respectively):

Immutable: