• Added postfix ++ operator
• Added ** as an integer exponentiation operator (this previously was a deprecated alias for ^)
• Added protected class fields
• Added $object syntax for table creation
• Added $include
• Added $haltcompiler
• Trailing commas are now allowed for arguments, parameters, and destructuring
• String interpolation now implicitly calls tostring on each interpolation value
• Deprecated the optional 'global' keyword

Type System:

• Added any and nil type hints
• Added type hinting for multiple return values
• Added complex type hinting for tables to specify fields
• Type hints for function type can now also specify the parameters and returns
• Added $type syntax for named types (this replaces the constexpr call $type(x))
• Added $declare to set the type of a global
• Added $getproptype to query the parser's idea of a variable's type

Standard Library:

• Bigint
  • Added bigint.abs, bigint.gcd, bigint.isprobableprime
  • Added bigint.export, bigint.import
  • Added __unm metamethod to bigints
• Crypto
  • Added curve25519 to crypto.generatekeypair
  • Added crypto.hmac
  • Added crypto.fnv1a32
  • Added crypto.x25519
  • Added crypto.derive
  • Added RSA OAEP modes to crypto.encrypt & crypto.decrypt (rsa-sha1, rsa-sha256, rsa-sha384, rsa-sha512)
  • Added optional offset parameter to crypto.decompress
• FFI
  • Added ffi.callback [DOCS NOTE: This does not work when W^X is enforced by the platform.]
• IO
  • Added io.unique
  • Added io.symlink [DOCS NOTE: Requires admin privileges on Windows]
• JSON
  • Added MessagePack support to json.encode and json.decode
• Math
  • Added math.trunc, math.cbrt, math.hypot
  • Added math.inf as an alias for math.huge
• OS
  • Added os.dnsresolve [DOCS NOTE: Unavailable under Android and WASM]
• Socket
  • Added alpn option to socket.starttls
  • Added early_data option to client-side socket.starttls
• String
  • Added string.span
• Table
  • Added table.create [DOCS NOTE: This is from Lua 5.5]
  • Added table.clone
• UTF8
  • utf8.offset now also returns the final position of the codepoint [DOCS NOTE: This is from Lua 5.5]