Lua Fun is a high-performance functional programming library designed for LuaJIT tracing just-in-time compiler.
Let’s see an example:
-- Functional style require "fun" () n = 100 x = sum(map(function(x) return x^2 end, take(n, tabulate(math.sin)))) -- calculate sum(sin(x)^2 for x in 0..n-1) print(x) 50.011981355266
-- Object-oriented style local fun = require "fun" n = 100 x = fun.tabulate(math.sin):take(n):map(function(x) return x^2 end):sum() -- calculate sum(sin(x)^2 for x in 0..n-1) print(x) 50.011981355266
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 initilization code -- ->LOOP: 0bcaffd0 movsd [rsp+0x8], xmm7 0bcaffd6 addsd xmm4, xmm5 0bcaffda ucomisd xmm6, xmm1 0bcaffde jnb 0x0bca0028 ->6 0bcaffe4 addsd xmm6, xmm0 0bcaffe8 addsd xmm7, xmm0 0bcaffec fld qword [rsp+0x8] 0bcafff0 fsin 0bcafff2 fstp qword [rsp] 0bcafff5 movsd xmm5, [rsp] 0bcafffa mulsd xmm5, xmm5 0bcafffe 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?