RREDUCE

(RREDUCE <function> <list> [<initial>])


If the <list> is, e.g., (1 2 3 ... n-1  n), then the result of

    (RREDUCE <fun> <list>) 

is the same as for 

    (<fun> 1 (<fun> 2 (<fun> 3 ... (<fun> n-1 n))...))), 

and the result of

    (RREDUCE <fun> <list> <initial>) 

is the same as for 

    (<fun> 1 (<fun> 2 (<fun> 3 ... (<fun> n <initial>))...)))


This function equals to the Common Lisp 

   (REDUCE <function> <list> :from-end t [:initial-value <initial>])

The only exception is that when <initial> isn't given and the <list> is
empty; Common Lisp calls the <function> with no args in this case, whule
InteLib Lisp doesn't call it and just returns the empty list.