Add spec suites for numbers/arithmetic, strings (str + clojure.string), and
type/value predicates. Bugs they caught and fixed:
- <, >, <=, >= were binary-only; now variadic ((< 1 2 3) chains)
- seq? was true for vectors; vectors are not ISeq in Clojure, so (seq? [1])
is now false (true only for lists/lazy-seqs)
- clojure.string/index-of and last-index-of were 1-based (stray inc); now
0-based per Clojure
Corrected a systematic-coverage assertion that encoded the old seq? bug.
jpm test green, conformance 218/218.