- case: quote list literals (read as arrays) in constant position so a wrapped
list ((a b c)) matches by value instead of being evaluated as a call; symbol
constants already quoted. Vector/map/set constants already worked. case errors
in the suite drop to 0 (60 pass).
- associative?: true only for vectors (pvec) and maps (phm/struct/sorted-map),
not lists/tuples-from-seq-fns/lazy-seqs/sets.
- reversible?: true for vectors and sorted-map/sorted-set only.
- update: coerce f via as-fn so (update m k :kw)/(update m k a-set) work; extra
args already handled.
- nth: (nth nil i)/(nth nil i default) returns nil/default instead of throwing.
clojure-test-suite pass 3649->3678, errors 122->105, clean files 44->46.
associative?/reversible? files now fully clean. spec: predicates + control/case.
jpm test green.