[R] Iteration idioms & laziness

[Uwe Ligges]

Alexander Søndergaard wrote:
> Hi all,
> 
> I'm new to R. Having a functional background, I was wondering what's
> the idiomatic way to iterate. It seems that for loops are the default
> given there's no tail-call optimization.
> 
> I'm curious to know whether there is a way to transform the following
> toy snippet into something that doesn't eat up gigabytes of memory
> (like it's for loop counterpart) using laziness:



> Reduce('+', seq(1,1e6))


In this case

   sum(as.numeric(seq(1, 1e6)))

or according to Gauss

   1e6 * (1e6+1) / 2

but for more complicated problems it might be sensible to go the loop 
way ...

Uwe Ligges



> Thanks!
> 
> Best regards,
> A.S.
> 
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