Summary

Tracking issue for wave 2 of the stdlib parity program — API-level (not module-level) gaps found by a deeper cross-language comparison against Rust std, Go std, Zig std, Odin core, Python stdlib and Node. Method and raw data: public-API inventories built from source and name-normalized against vlib's 7,984 library names across 501 modules; wave-1-shipped names excluded.

Prior art: #639 (closed), #30345 (wave-1 tracking). No duplicates found for any item below (searches run before filing).

Issues

#30482 math.stats: variance/stdev/quantiles/correlation + normal distribution
#30483 datatypes: heapq-compatible heap API
#30484 arrays: bisect_left/right + insort_left/right
#30485 math: lgamma, remainder, fma, classify, next_power_of_two, to_degrees…
#30486 strings/arrays: cut, split_after, equal_fold, index_byte, is_sorted…
#30487 io: reader combinators (read_byte, read_full, limited/tee/multi/section)
#30488 os: same_file, is_absolute, copy_file, user_*_dir, volume_name…
#30489 strconv.parse_bool + time add_date/weekday/clock
#30490 rand: Zipf distribution
#30491 difflib: unified/context/ndiff + get_close_matches

Each issue carries verified-absent evidence (names grepped in the vlib tree), a V-idiomatic API proposal, and a red-first test plan; each PR lands new files with v test / v fmt -verify / v missdoc / module-suite gates.

Deliberately excluded (verified not real gaps)

Name-only aliases: hasprefix↔starts_with, basename↔os.base, extension↔os.file_ext, itoa↔str, month/year↔Time fields
Inflated counts from Odin/Zig typed variants, compiler internals, Python internals (functools comparison wrappers, shutil _fastcopy block sizes)
Language-coupled design: Rc/Arc (sync.arc shipped in #30361), is_dst (needs timezone rules — noted as follow-up in #30489), read_at (needs a read_at method on os.File — noted as follow-up in #30487)

Activity

metif1216d ago

Final status: wave 2 complete (10/10)

Issue	Implementation	PR
#30482 math.stats: correlation/linear_regression/quantiles/multimode/NormalDist	`math/stats/regress.v`	#30506
#30483 heapq-compatible heap API	`datatypes/heapq.v`	#30508
#30484 bisect_left/right + insort_left/right	`arrays/bisect.v`	#30496
#30485 lgamma, remainder, fma, classify, next_power_of_two…	`math/float_ops.v`	#30499
#30486 split_after, equal_fold, last_index_any, contains_rune, is_sorted	`strings/text_ops.v`, `arrays/is_sorted.v`	#30501
#30487 read_byte/read_full + limited/tee/multi/section_reader	`io/reader_ops.v`	#30509
#30488 same_file, is_absolute, is_path_separator, copy_file, user_*_dir, volume_name	`os/path_ops.v`, `os/same_file_windows.c.v`	#30516
#30489 strconv.parse_bool + time weekday/add_date/clock	`strconv/parse_bool.v`, `time/date_ops.v`	#30518
#30490 rand: Zipf distribution	`rand/zipf.v`	#30527
#30491 difflib → only get_close_matches was a real gap	`strings/close_matches.v`	#30535 (closed)

What verification changed (documented in each PR)

Name-level comparison said these were missing; source verification showed several already existed under other names, and each PR shipped only the real gap:

variance/stdev/quantile/covariance → population_variance, sample_stddev, quantile, covariance in math.stats
cut → string.split_once; split_lines → split_into_lines; index_byte → index_u8; has_prefix → starts_with
unified/context diffs → vlib/arrays/diff.generate_patch; similarity → strings.similarity (Levenshtein/Dice/Jaro-Winkler)

Cross-cutting findings worth remembering

os.cp creates hard links — "a copy is a distinct object" needs a real read/write copy in tests.
CLOSED __global / init() in vlib: a __global breaks every in-module test in the same module (calrified during the park/unpark work).
Month conventions differ inside vlib/time: days_from_unix_epoch uses Hinnant's March-based months and days_in_month takes (month, year).
Interface boxing copies struct values; pass pointers to share state, and note strings.Builder does not satisfy io.Writer from another module.

All 10 PRs are open on metif12/v branches against vlang/v:master, each with red-first-proven tests and the v test / v fmt -verify / v missdoc gates.