What's wrong with your HEAD?

[pier4r]

(10-08-2018 03:36 PM)DavidM Wrote:  The big difference with LPOP/R is that they leave the residual list elements on the stack. This means that they both have a need of traversing and copying the entire list in order to return the complete results, thus incurring the performance penalties both of those steps require. The main benefit of something like LHEAD is that it would only need to deal with the first element, and thus it can operate much faster than something that has to scan/rebuild the entire list. If you don't need the residual list elements, LHEAD would be significantly faster than LPOP NIP.

Point! Then go for it!
Obviously LTAIL follows.