[Rd] [R] Successive subsets from a vector?

[hadley wickham]

> > Providing the ability to write assignment functions that don't duplicate
> > is a more urgent problem.
>
> You mean, for end-users?  It can be done via primitives.

Isn't this sort of a run-time optimisation?  I thought R generally
followed the functional programming model of immutable objects, copy
on modification.

As a general comment/question - it seems to me the R seems to be
moving away from a functional paradigm to be more OO (especially among
package developers).

> As I said in my reply on R-help, I don't see the original as at all a
> common problem.  About the only times where a bound on number of entries
> is unknown in advance is when reading from a connection (and there the
> internal code does uses doubling strategies), and in a iterative procedure
> with no limit on the number of iterations (not usually good practice).

Agreed - but it is a very common mistake, and this change could bring
large performance increases to any written in this way.  Of course,
you can only protect users from themselves to some extent, and I can
imagine many things that would be both more interesting to work on and
provide performance benefits for people who understand more about how
vectors work.

Regards,

Hadley