3 * Changes from version 5.0 to 5.1
 
   4   -------------------------------
 
   7   + new semantics for control variables of fors.
 
   8   + new semantics for setn/getn.
 
   9   + new syntax/semantics for varargs.
 
  10   + new long strings and comments.
 
  11   + new `mod' operator (`%')
 
  12   + new length operator #t
 
  13   + metatables for all types
 
  15   + new functions: lua_createtable, lua_get(set)field, lua_push(to)integer.
 
  16   + user supplies memory allocator (lua_open becomes lua_newstate).
 
  17   + luaopen_* functions must be called through Lua.
 
  19   + new configuration scheme via luaconf.h.
 
  20   + incremental garbage collection.
 
  21   + better handling of end-of-line in the lexer.
 
  22   + fully reentrant parser (new Lua function `load')
 
  23   + better support for 64-bit machines.
 
  24   + native loadlib support for Mac OS X.
 
  25   + standard distribution in only one library (lualib.a merged into lua.a)
 
  27 * Changes from version 4.0 to 5.0
 
  28   -------------------------------
 
  32   + standard libraries now packaged in tables.
 
  33   + tags replaced by metatables and tag methods replaced by metamethods,
 
  36   + each function can have its own global table, which can be shared.
 
  37   + new __newindex metamethod, called when we insert a new key into a table.
 
  38   + new block comments: --[[ ... ]].
 
  42   + new syntax "local function".
 
  43   + (f()) returns the first value returned by f.
 
  44   + {f()} fills a table with all values returned by f.
 
  45   + \n ignored in [[\n .
 
  46   + fixed and-or priorities.
 
  47   + more general syntax for function definition (e.g. function a.x.y:f()...end).
 
  48   + more general syntax for function calls (e.g. (print or write)(9)).
 
  49   + new functions (time/date, tmpfile, unpack, require, load*, etc.).
 
  51   + chunks are loaded by using lua_load; new luaL_loadfile and luaL_loadbuffer.
 
  52   + introduced lightweight userdata, a simple "void*" without a metatable.
 
  53   + new error handling protocol: the core no longer prints error messages;
 
  54     all errors are reported to the caller on the stack.
 
  55   + new lua_atpanic for host cleanup.
 
  56   + new, signal-safe, hook scheme.
 
  59   + new, faster, register-based virtual machine.
 
  60   + support for external multithreading and coroutines.
 
  61   + new and consistent error message format.
 
  62   + the core no longer needs "stdio.h" for anything (except for a single
 
  63     use of sprintf to convert numbers to strings).
 
  64   + lua.c now runs the environment variable LUA_INIT, if present. It can
 
  65     be "@filename", to run a file, or the chunk itself.
 
  66   + support for user extensions in lua.c.
 
  67     sample implementation given for command line editing.
 
  68   + new dynamic loading library, active by default on several platforms.
 
  69   + safe garbage-collector metamethods.
 
  70   + precompiled bytecodes checked for integrity (secure binary dostring).
 
  71   + strings are fully aligned.
 
  72   + position capture in string.find.
 
  73   + read('*l') can read lines with embedded zeros.
 
  75 * Changes from version 3.2 to 4.0
 
  76   -------------------------------
 
  78   + new "break" and "for" statements (both numerical and for tables).
 
  79   + uniform treatment of globals: globals are now stored in a Lua table.
 
  80   + improved error messages.
 
  81   + no more '$debug': full speed *and* full debug information.
 
  82   + new read form: read(N) for next N bytes.
 
  83   + general read patterns now deprecated.
 
  84     (still available with -DCOMPAT_READPATTERNS.)
 
  85   + all return values are passed as arguments for the last function
 
  86     (old semantics still available with -DLUA_COMPAT_ARGRET)
 
  87   + garbage collection tag methods for tables now deprecated.
 
  88   + there is now only one tag method for order.
 
  90   + New API: fully re-entrant, simpler, and more efficient.
 
  93   + faster than ever: cleaner virtual machine and new hashing algorithm.
 
  94   + non-recursive garbage-collector algorithm.
 
  95   + reduced memory usage for programs with many strings.
 
  96   + improved treatment for memory allocation errors.
 
  97   + improved support for 16-bit machines (we hope).
 
  98   + code now compiles unmodified as both ANSI C and C++.
 
  99   + numbers in bases other than 10 are converted using strtoul.
 
 100   + new -f option in Lua to support #! scripts.
 
 101   + luac can now combine text and binaries.
 
 103 * Changes from version 3.1 to 3.2
 
 104   -------------------------------
 
 105   + redirected all output in Lua's core to _ERRORMESSAGE and _ALERT.
 
 106   + increased limit on the number of constants and globals per function
 
 108   + debugging info (lua_debug and hooks) moved into lua_state and new API
 
 109     functions provided to get and set this info.
 
 110   + new debug lib gives full debugging access within Lua.
 
 111   + new table functions "foreachi", "sort", "tinsert", "tremove", "getn".
 
 112   + new io functions "flush", "seek".
 
 114 * Changes from version 3.0 to 3.1
 
 115   -------------------------------
 
 116   + NEW FEATURE: anonymous functions with closures (via "upvalues").
 
 118     - local variables in chunks.
 
 119     - better scope control with DO block END.
 
 120     - constructors can now be also written: { record-part; list-part }.
 
 121     - more general syntax for function calls and lvalues, e.g.:
 
 124       f"string" is sugar for f("string")
 
 125   + strings may now contain arbitrary binary data (e.g., embedded zeros).
 
 126   + major code re-organization and clean-up; reduced module interdependecies.
 
 127   + no arbitrary limits on the total number of constants and globals.
 
 128   + support for multiple global contexts.
 
 129   + better syntax error messages.
 
 130   + new traversal functions "foreach" and "foreachvar".
 
 131   + the default for numbers is now double.
 
 132     changing it to use floats or longs is easy.
 
 133   + complete debug information stored in pre-compiled chunks.
 
 134   + sample interpreter now prompts user when run interactively, and also
 
 135     handles control-C interruptions gracefully.
 
 137 * Changes from version 2.5 to 3.0
 
 138   -------------------------------
 
 139   + NEW CONCEPT: "tag methods".
 
 140     Tag methods replace fallbacks as the meta-mechanism for extending the
 
 141     semantics of Lua. Whereas fallbacks had a global nature, tag methods
 
 142     work on objects having the same tag (e.g., groups of tables).
 
 143     Existing code that uses fallbacks should work without change.
 
 144   + new, general syntax for constructors {[exp] = exp, ... }.
 
 145   + support for handling variable number of arguments in functions (varargs).
 
 146   + support for conditional compilation ($if ... $else ... $end).
 
 147   + cleaner semantics in API simplifies host code.
 
 148   + better support for writing libraries (auxlib.h).
 
 149   + better type checking and error messages in the standard library.
 
 150   + luac can now also undump.
 
 152 * Changes from version 2.4 to 2.5
 
 153   -------------------------------
 
 154   + io and string libraries are now based on pattern matching;
 
 155     the old libraries are still available for compatibility
 
 156   + dofile and dostring can now return values (via return statement)
 
 157   + better support for 16- and 64-bit machines
 
 158   + expanded documentation, with more examples
 
 160 * Changes from version 2.2 to 2.4
 
 161   -------------------------------
 
 162   + external compiler creates portable binary files that can be loaded faster
 
 163   + interface for debugging and profiling
 
 164   + new "getglobal" fallback
 
 165   + new functions for handling references to Lua objects
 
 166   + new functions in standard lib
 
 167   + only one copy of each string is stored
 
 168   + expanded documentation, with more examples
 
 170 * Changes from version 2.1 to 2.2
 
 171   -------------------------------
 
 172   + functions now may be declared with any "lvalue" as a name
 
 173   + garbage collection of functions
 
 176 * Changes from version 1.1 to 2.1
 
 177   -------------------------------
 
 178   + object-oriented support
 
 180   + simplified syntax for tables
 
 181   + many internal improvements