Lua Functional

Lua Fun is a high-performance functional programming library for Lua designed with LuaJIT's trace compiler in mind.

Lua Fun provides a set of more than 50 programming primitives typically found in languages like Standard ML, Haskell, Erlang, JavaScript, Python and even Lisp. High-order functions such as map, filter, reduce, zip, etc., make it easy to write simple and efficient functional code.

Let's see an example:

> -- Functional style
> require "fun" ()
> -- calculate sum(x for x^2 in 1..n)
> n = 100
> print(reduce(operator.add, 0, map(function(x) return x^2 end, range(n))))
328350

> -- Object-oriented style
> local fun = require "fun"
> -- calculate sum(x for x^2 in 1..n)
> print(fun.range(n):map(function(x) return x^2 end):reduce(operator.add, 0))
328350

Lua Fun takes full advantage of the innovative tracing JIT compiler to achieve transcendental performance on nested functional expressions. Functional compositions and high-order functions can be translated into efficient machine code. Can you believe it? Just try to run the example above with luajit -jdump and see what happens:

-- skip some initialization code --
->LOOP:
0bcaffd0  movaps xmm5, xmm7
0bcaffd3  movaps xmm7, xmm1
0bcaffd6  addsd xmm7, xmm5
0bcaffda  ucomisd xmm7, xmm0
0bcaffde  jnb 0x0bca0024        ->5
0bcaffe4  movaps xmm5, xmm7
0bcaffe7  mulsd xmm5, xmm5
0bcaffeb  addsd xmm6, xmm5
0bcaffef  jmp 0x0bcaffd0        ->LOOP
---- TRACE 1 stop -> loop

The functional chain above was translated by LuaJIT to (!) one machine loop containing just 10 CPU assembly instructions without CALL. Unbelievable!

Readable? Efficient? Can your Python/Ruby/V8 do better?

Status

Lua Fun is in an early alpha stage. The library fully documented and covered with unit tests.

LuaJIT 2.1 alpha is recommended. The library designed in mind of fact that LuaJIT traces tail-, up- and down-recursion and has a lot of byte code optimizations. Lua 5.1-5.3 are also supported.

This is master (development) branch. API may be changed without any special notice. Please use stable branch for your production deployments. If you still want to use master, please don't forget to grep git log for Incompatible API changes message. Thanks!

Please check out documentation for more information.

Misc

Lua Fun is distributed under the MIT/X11 License - (same as Lua and LuaJIT).

The library was written to use with Tarantool - an efficient in-memory store and an asynchronous Lua application server.

See Also

• Documentation
• RockSpec
• RPM/DEB packages
• Hacking
• lua-l@lists.lua.org
• luajit@freelists.org
• roman@tsisyk.com

Please "Star" the project on GitHub to help it to survive! Thanks!

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Lua Fun. Simple, Efficient and Functional. In Lua. With JIT.