Re: Little fun with vararg
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- Subject: Re: Little fun with vararg
- From: Sean Conner <sean@...>
- Date: Tue, 5 Aug 2014 12:19:46 -0400
It was thus said that the Great Roberto Ierusalimschy once stated:
> > I don't know. This
> >
> > x = 5
> > function F(...)
> > return F(x,...)
> > end
> >
> > print(F())
> >
> > is taking an awful long time to fail.
By "long time to fail" I mean "it's stuck in an infinite loop."
> I believe this is O(n^2), as each new call copies all accumulated
> arguments. Change your function to this and you will see the
> slowdown:
>
> local x = 0
> function F(...)
> x = x + 1
> print(x)
> return F(x,...)
> end
>
> print(F())
I did that, and it's currently stuck (20 minutes) in an infinite loop.
-spc (Tail calls for the win!)