Csv
Csv module: streaming CSV parser.
Two consumption modes: each_row(path, delimiter, mode, callback) -- streaming; guaranteed cleanup read_all(path, delimiter, mode) -- eager; for small files
Modes: :simple -- split on delimiter only; no quoting :rfc4180 -- full RFC 4180: quoted fields, "" escapes, embedded newlines
Convenience: read_csv(path) -- comma-delimited, :rfc4180, eager each_csv_row(path, callback) -- comma-delimited, :rfc4180, streaming