[Openmcl-devel] bug?

Tim Bradshaw tfb at tfeb.org
Mon Dec 7 23:27:37 UTC 2009


On 7 Dec 2009, at 22:36, Paul Krueger wrote:

> I guess I would have expected that if the ":from-end t" was honored
> that #'plusp would never be called on the 'a element, but obviously
> that isn't the case.

At a slight tangent: is there a way to implement such a search, on a  
list, efficiently?  By "efficiently" I mean something like "without  
doing something equivalent to making a copy of the list".  Obviously  
it is easy to do this on anything with fast random access, but I can't  
see a way on a list.

The two ways I can see of doing it are: making a backwards copy of the  
list, or recursing (but not tail-recursing) down it and doing the  
tests on the way back up.  Is there any other approach?

--tim



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