seq

(seq coll)

Answers the seq view of coll: a lazy wrapper realizes one level (never past it, so infinite seqs stay infinite); a list passes through untouched, a vector or string coerces element by element, a map contributes one two-vector per entry and a set one member per element, both in the table's walk order (unspecified). nil is empty. A Java Iterable contributes its elements, a Java Map one two-vector per entry and a CharSequence its characters, read whole when the seq is taken (interpreter and JVM). Anything else (a keyword, false, a number) signals IllegalArgumentException, like the oracle.

The empty result of every seq verb is nil. There is no chunking: a lazy seq realizes one element at a time.