This is version 3.1.

* Changes from version 3.0 to 3.1
  + NEW FEATURE: anonymous functions with closures (via "upvalues").
  + new syntax:
    - local variables in chunks.
    - better scope control with DO block END.
    - constructors can now be also written: { record-part; list-part }.
    - more general syntax for function calls and lvalues, e.g.:
      f(x).y=1
      o:f(x,y):g(z)
      f"string" is sugar for f("string")
  + strings may now contain arbitrary binary data (e.g., embedded zeros).
  + major code re-organization and clean-up; reduced module interdependecies.
  + no arbitrary limits on the total number of constants and globals.
  + support for multiple global contexts.
  + better syntax error messages.
  + new traversal functions "foreach" and "foreachvar".
  + the default for numbers is now double.
    changing it to use floats or longs is easy.
  + complete debug information stored in pre-compiled chunks.
  + sample interpreter now prompts user when run interactively, and also
    handles control-C interruptions gracefully.

* Changes from version 2.5 to 3.0
  + NEW CONCEPT: "tag methods".
    Tag methods replace fallbacks as the meta-mechanism for extending the
    semantics of Lua. Whereas fallbacks had a global nature, tag methods
    work on objects having the same tag (e.g., groups of tables).
    Existing code that uses fallbacks should work without change.
  + new, general syntax for constructors {[exp] = exp, ... }.
  + support for handling variable number of arguments in functions (varargs).
  + support for conditional compilation ($if ... $else ... $end).
  + cleaner semantics in API simplifies host code.
  + better support for writing libraries (auxlib.h).
  + better type checking and error messages in the standard library.
  + luac can now also undump.

* Changes from version 2.4 to 2.5
  + io and string libraries are now based on pattern matching;
    the old libraries are still available for compatibility
  + dofile and dostring can now return values (via return statement)
  + better support for 16- and 64-bit machines
  + expanded documentation, with more examples

* Changes from version 2.2 to 2.4
  + external compiler creates portable binary files that can be loaded faster
  + interface for debugging and profiling
  + new "getglobal" fallback
  + new functions for handling references to Lua objects
  + new functions in standard lib
  + only one copy of each string is stored
  + expanded documentation, with more examples

* Changes from version 2.1 to 2.2
  + functions now may be declared with any "lvalue" as a name
  + garbage collection of functions
  + support for pipes

* Changes from version 1.1 to 2.1
  + object-oriented support
  + fallbacks
  + simplified syntax for tables
  + many internal improvements