partition-all

(partition-all n coll) / (partition-all n step coll) / (partition-all n)

Answers coll's seq in groups of n, stepping by step (n without one); unlike partition, the short tail is kept. A lazy input answers a lazy seq, a strict one a strict list. A non-positive size or step signals (the oracle answers an endless seq of ()). (partition-all n) is its transducer: it steps vectors and flushes the short tail at the end. As a value it takes one, two or three arguments.