Lus 1.6.0

2026-06-10

Lus now installs itself. On Linux and macOS, curl -fsSL https://lus.dev/install.sh | sh downloads the right binary, verifies it, and puts lus on your PATH; on Windows, lus-setup.exe does the same with a per-user installer. Release binaries are now self-contained — statically linked, runnable on a clean machine — and every release publishes a SHA256SUMS asset. Under the hood, this release also makes the VM substantially faster through intrinsified standard-library fastcalls.

• Added fromcsv and tocsv to parse CSV files.
• Added VM-intrinsified fastcalls for common standard library functions, reducing call overhead by ~31% (1.46x geometric mean speedup across 57 benchmarks).
  • When the compiler detects a call to a known stdlib function with the expected argument count, it emits OP_FASTCALL instead of OP_CALL. The VM validates at runtime that the function hasn’t been replaced and executes the operation inline, falling back to a normal call otherwise.
  • Fastcall emission can be disabled by passing --no-fastcall to lus.
• Added --readonly-env flag that freezes _ENV and all module tables after initialization, enabling fast-dispatch fastcalls that skip runtime validation.
• Added --gc-pause N flag to bound how far the heap may grow past the live set before a new GC cycle starts in incremental mode.
• Added --strip-debug flag that drops debug information from every loaded chunk to save memory (~15% of loaded-code memory on small chunks, more on line-heavy files)
• Regular long strings no longer store a redundant content pointer, saving 8 bytes per long string.
• The string table now grows at a 1.5 load factor instead of 1.0, shrinking its bucket array by up to a third for string-heavy programs.
• for ... in pairs(t)/ipairs(t)/next, t loops over tables now walk the table directly in the VM instead of calling the iterator function each step (pairs ~1.8x, ipairs ~2.3x faster).
• Indexing tables with string variables (t[k]) now takes the same short-string fast path as constant fields, ~15% faster.
• Integer-to-string conversion uses a direct conversion loop instead of snprintf (~20% faster interpolation-heavy code).
• Release binaries for Linux and macOS are now built with profile-guided optimization (tools/pgo-build.sh), 15–45% faster across VM micro-benchmarks than a plain release build.
• The worker library no longer pre-allocates a table from an untrusted declared size while deserializing messages.
• Workers now inherit their parent’s pledges (sealed).
• fs permission checks now canonicalize paths and fail closed.
• network:http/network:tcp permission checks now match the URL/host structurally, so a pledge for example.com no longer also permits example.com.net.
• Passing any -P/--pledge permission now seals the pledge store after startup.
• Replaced the short-string hash with a full-content hash.
• Fixed network.tcp.bind not checking network:tcp permission.
• Fixed fs.createdirectory and fs.createlink not checking fs:write permission.
• Fixed fs.type and fs.follow not checking fs:read permission.
• Fixed JSON parser not handling \b, \f, \/, and \uXXXX escape sequences in object keys.
• Fixed msgqueue_push crashing on allocation failure in the worker library.
• Fixed nested catch blocks in the same function corrupting control flow on a subsequent error.
• Fixed catch not closing to-be-closed variables when catching an error, which corrupted state when catching errors raised by standard-library functions that build internal buffers.
• Fixed slice expressions not validating that their bounds are integers.
• Fixed slicing an inline table constructor (e.g. ({1,2,3})[a,b]) producing the wrong result.
• Fixed table.clone(t, true) crashing on deeply nested tables.
• Fixed debug.parse leaving the garbage collector permanently disabled if it ran out of memory while building its result.
• Fixed an intermittent attempt to modify a readonly table error caused by a value collision between the readonly-table flag and the table pre-set hash-node encoding.
• Fixed a buffer overflow in the Windows path canonicalizer on over-long paths.
• Gated the io library (io.open, io.lines, io.input, io.output, io.tmpfile) behind fs:read/fs:write pledges.
• Gated native module loading (package.loadlib and require of C modules) behind the load and fs:read pledges.
• Gated os.getenv behind a new env pledge and os.tmpname behind fs:write.
• Backport upstream Lua 5.5 fixes:
  • https://github.com/lua/lua/commit/3360710bd3ea8da06fa5062f9d10c2719083097c
  • https://github.com/lua/lua/commit/b60e2bcd7ca4c349bd6ee7a8e929f55e04f7ca87
  • https://github.com/lua/lua/commit/10eb89d1141dc528806b32401e408e36fb2f3bf5
  • https://github.com/lua/lua/commit/36d5d2b2847906aa3b66e020d5d894a14ba2bf90
  • https://github.com/lua/lua/commit/377cbea61b2688b21c7d243fc0f42498851df794
  • https://github.com/lua/lua/commit/51269bd783c9371252947b26cc865239dbb0153d
  • https://github.com/lua/lua/commit/f1bb2773bba8b16f0f01c00e59a7be541ef88cb7
  • https://github.com/lua/lua/commit/efddc2309c5ff8a1842bea8a9c0d7d4a5d6e1e60
  • https://github.com/lua/lua/commit/c037162a1a657088d722f550e287015525bb2259
  • https://github.com/lua/lua/commit/29cf284089d543408d726440a3f1acaecdf73636
  • https://github.com/lua/lua/commit/d0bd25d2e7fb393a6d0a73645a099f9c3b9cc0a8
  • https://github.com/lua/lua/commit/3228a97c6a953dcf397944161bb64b12f1ff5384
  • https://github.com/lua/lua/commit/4c5d5063a54c0088729b16fb25a333f0f9f836b0
  • https://github.com/lua/lua/commit/ae23e726018bd31a25c1279600328d90207ec81c
  • https://github.com/lua/lua/commit/0da6d320f757bc9241a33df06f3597598845cf0a
  • https://github.com/lua/lua/commit/36c1f6d949a4d3dfcbe898d80b1be1efe8e5325c
  • https://github.com/lua/lua/commit/53b41d0cddd80bf33fdc631bdd32e3ba53842b89

table#

• Added table.sum to compute the sum of numeric values.
• Added table.mean to compute the arithmetic mean.
• Added table.median to compute the median.
• Added table.stdev to compute the standard deviation.
• Added table.map to apply a function to each element.
• Added table.filter to select elements by predicate.
• Added table.reduce to fold a table into a single value.
• Added table.groupby to group elements by a key function.
• Added table.sortby to sort in-place by a key function.
• Added table.zip to combine tables element-wise into tuples.
• Added table.unzip to split tuples into separate tables.
• Added table.transpose to transpose a 2D matrix.
• Added table.reshape to reshape a 1D array into a matrix.
• Added table.compact (and C API lua_compacttable) to shrink a table’s internal storage to fit its current contents.

string#

• Added string.split to split a string on a delimiter.
• Added string.join to join table elements with a delimiter.
• Added string.trim to remove leading and trailing characters.
• Added string.ltrim to remove leading characters.
• Added string.rtrim to remove trailing characters.

vector#

• Added vector.archive.gzip.compress and vector.archive.gzip.decompress for gzip compression.
• Added vector.archive.deflate.compress and vector.archive.deflate.decompress for raw deflate compression.
• Added vector.archive.zstd.compress and vector.archive.zstd.decompress for Zstandard compression.
• Added vector.archive.brotli.compress and vector.archive.brotli.decompress for Brotli compression.
• Added vector.archive.lz4.compress, vector.archive.lz4.decompress, and vector.archive.lz4.decompress_hc for LZ4 compression.