Lua 5.5.0 was released on 22 Dec 2025. Its main new features are declarations for global variables, named vararg tables, more compact arrays, and major garbage collections done incrementally.
Here are the main changes introduced in Lua 5.5. The reference manual lists the incompatibilities that had to be introduced.
Main changes
- declarations for global variables
- named vararg tables
- for-loop variables are read only
- floats are printed in decimal with enough digits to be read back correctly.
- more levels for constructors
- table.create
- utf8.offset returns also final position of character
- external strings (that use memory not managed by Lua)
- new functions luaL_openselectedlibs and luaL_makeseed
- major garbage collections done incrementally
- more compact arrays (large arrays use about 60% less memory)
- lua.c loads 'readline' dynamically
- static (fixed) binaries (when loading a binary chunk in memory, Lua can reuse its original memory in some of the internal structures)
- dump and undump reuse all strings
- auxiliary buffer reuses buffer when it creates final string