This manual is for an old version of Hazelcast Jet, use the latest stable version.

Traverser is a very simple functional interface whose shape matches that of a Supplier, but with a contract specialized for the traversal over a sequence of non-null items: each call to its next() method returns another item of the sequence until exhausted, then keeps returning null. The point of this type is the ability to implement traversal over any kind of dataset or lazy sequence with minimum hassle: often just by providing a one-liner lambda expression. This makes it very easy to integrate into Jet's convenience APIs for cooperative processors.

Traverser also supports some default methods that facilitate building a simple transformation layer over the underlying sequence: map, filter, and flatMap.