nreverse sequence    reversed-sequence

reversed-sequence - a sequence.

reverse and nreverse differ in that reverse always creates and returns a new sequence, whereas nreverse might modify and return the given sequence. reverse never modifies the given sequence.

For reverse, if sequence is a vector, the result is a fresh simple array of rank one that has the same actual array element type as sequence. If sequence is a list, the result is a fresh list.

For nreverse, if sequence is a vector, the result is a vector that has the same actual array element type as sequence. If sequence is a list, the result is a list.

For nreverse, sequence might be destroyed and re-used to produce the result. The result might or might not be identical to sequence. Specifically, when sequence is a list, nreverse is permitted to setf any part, car or cdr, of any cons that is part of the list structure of sequence. When sequence is a vector, nreverse is permitted to re-order the elements of sequence in order to produce the resulting vector.

 (setq str "abc")  "abc"
 (reverse str)  "cba"
 str  "abc"
 (setq str (copy-seq str))  "abc"
 (nreverse str)  "cba"
 str  implementation-dependent
 (setq l (list 1 2 3))  (1 2 3)
 (nreverse l)  (3 2 1)
 l  implementation-dependent