add README_Lua

README.rst

@@ -111,6 +111,7 @@ More info
 * `Dirk Eddelbuettel <http://dirk.eddelbuettel.com/>`__ provides an `R version of Annoy <http://dirk.eddelbuettel.com/code/rcpp.annoy.html>`__.
 * `Andy Sloane <http://www.a1k0n.net/>`__ provides a `Java version of Annoy <https://github.com/spotify/annoy-java>`__ although currently limited to cosine and read-only.
 * There is `experimental support for Go <https://github.com/spotify/annoy/blob/master/README_GO.rst>`__ provided by Taneli Leppä.
+* Boris Nagaev wrote `Lua bindings <https://github.com/spotify/annoy/blob/master/README_Lua.md>`__.
 * `Presentation from New York Machine Learning meetup <http://www.slideshare.net/erikbern/approximate-nearest-neighbor-methods-and-vector-models-nyc-ml-meetup>`__ about Annoy
 * Radim Řehůřek's blog posts comparing Annoy to a couple of other similar Python libraries: `Intro <http://radimrehurek.com/2013/11/performance-shootout-of-nearest-neighbours-intro/>`__, `Contestants <http://radimrehurek.com/2013/12/performance-shootout-of-nearest-neighbours-contestants/>`__, `Querying <http://radimrehurek.com/2014/01/performance-shootout-of-nearest-neighbours-querying/>`__
 * `ann-benchmarks <https://github.com/erikbern/ann-benchmarks>`__ is a benchmark for several approximate nearest neighbor libraries. Annoy seems to be fairly competitive, especially at higher precisions:

README_Lua.md

@@ -0,0 +1,101 @@
+Install
+-------
+
+To install, you'll need Lua (binary + library) and LuaRocks.
+
+If you have Python and Pip, you can get Lua and LuaRocks
+using [hererocks](https://github.com/mpeterv/hererocks/),
+written by Peter Melnichenko.
+
+```
+  pip install hererocks
+  hererocks here --lua 5.1 --luarocks 2.2
+```
+
+This command installs Lua and LuaRocks locally to directory `here`.
+To activate it, add `here/bin` to `PATH`:
+
+```
+  export PATH="$(pwd)/here/bin/:$PATH"
+```
+
+Then you can use commands `lua`, `luarocks`,
+and tools installed by `luarocks`.
+
+To build and install `annoy`, type:
+
+```
+  luarocks make
+```
+
+Background
+----------
+
+See the main README.
+
+Lua code example
+----------------
+
+```lua
+local annoy = require "annoy"
+
+local f = 3
+local t = annoy.AnnoyIndex(f) -- Length of item vector that will be indexed
+for i = 0, 999 do
+  local v = {math.random(), math.random(), math.random()}
+  t:add_item(i, v)
+end
+
+t:build(10) -- 10 trees
+t:save('test.ann')
+
+-- ...
+
+local u = annoy.AnnoyIndex(f)
+u:load('test.ann') -- super fast, will just mmap the file
+
+-- find the 10 nearest neighbors
+local neighbors = u:get_nns_by_item(0, 10)
+for rank, i in ipairs(neighbors) do
+  print("neighbor", rank, "is", i)
+end
+```
+
+Full Lua API
+------------
+
+Lua API closely resembles Python API, see main README.
+
+
+Tests
+-------
+
+File `test/annoy_test.lua` is the literal translation of
+`test/annoy_test.py` from Python+Nosetests to Lua+Busted.
+
+To run tests, you need [Busted](http://olivinelabs.com/busted/),
+Elegant Lua unit testing. To install it, type:
+
+```
+  luarocks install busted
+```
+
+To run tests, type:
+
+```
+  busted test/annoy_test.lua
+```
+
+It will take few minutes to execute.
+
+Discuss
+-------
+
+There might be some memory leaks if inputs are incorrect.
+Some functions allocate stack objects calling Lua functions throwing
+Lua errors (e.g., `luaL_checkinteger`). A Lua error may omit calling
+C++ destructors when unwinding the stack. (If it does, depends on
+the Lua implementation and platform being in use.)
+
+Lua binding was written by Boris Nagaev.
+You can contact me via email (see https://github.com/starius).