on 1 March 2013
For a while I was looking for a way to make C/++ applications easier to write. Once I realised that Lua was such a powerful scripting language and all for the low low price of about 200kb and a liberal MIT license I was amazed!
The reference manual and Programming in Lua Volume 1 are available on line which is plenty to get you familiar with the basics. Once you've grasped those, YOU NEED THIS BOOK!
Its style is the same as PiL#1 which is to say comprehensive and well written. The author explains every bit of the language and makes clear what is essential and what is 'common practice'. He also provides useful tips on alternative (Lua-like) ways of doing things which don't always come naturally to C/++ programmers.
The first third deals with the basics of writing Lua scripts. The second third explains some more advanced ways of scripting along with the Lua standard libraries. The last third tends to deal integrating Lua into your own C/++ applications. For this last third, it is probably useful having a copy of the Lua source (also on line) and compiling in your own environment to experiment with some of the C API. Throughout the book there are regular annotations where something relevant has changed since 5.1.
The official Lua mailing list is also a very active list that's worth signing up for as well. The author actively participates in the list too.