Re: LuaJIT & iterator sequences (a question for Mike Pall)
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- Subject: Re: LuaJIT & iterator sequences (a question for Mike Pall)
- From: Mark Hamburg <mark@...>
- Date: Sun, 3 Jan 2010 08:59:25 -0800
On Jan 3, 2010, at 4:57 AM, Mike Pall wrote:
> The sequence version runs in the interpreter, because calls to
> vararg functions are not compiled, yet. The open coded version
> runs 33x faster than with Lua.
>
> But do you really seriously think that this:
>
> for v in s.seq( plus_one, 0, 0 )( s.take, limit )( s.filter, is_odd )( s.map, square )( s.iterator ) do
> total = total + v
> end
>
> is more readable than this:
>
> for i=1,limit do total = total + i*i*(i%2) end
>
> I mean ... apart from the fact that the latter is 80x faster than
> the former under LuaJIT. :-)
No, I don't think it's clearer. The multiply by i % 2 is subtle, but I'd thought about something similar as a way to optimize the test code if my goal had been to avoid conditionals.
I do, however, think examples like:
iseq(io.lines(arg[1])) (take,10) (foreach, print)
Are probably clearer than:
local count = 0
for line in io.lines(arg[1]) do
count = count + 1
if 10 < count then break end
print( line )
end
Mark