cl-reduce doc string improvement

* lisp/emacs-lisp/cl-seq.el (cl-reduce): Explain what happens when
using :from-end (bug#57273).

1 files changed, 4 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/cl-seq.el b/lisp/emacs-lisp/cl-seq.el
index 64ae05bf2a0..60e204eaf51 100644
--- a/lisp/emacs-lisp/cl-seq.el
+++ b/lisp/emacs-lisp/cl-seq.el
@@ -139,6 +139,10 @@ only case where FUNCTION is called with fewer than two arguments.
 If SEQ contains exactly one element and no :INITIAL-VALUE is
 specified, then return that element and FUNCTION is not called.
 
+If :FROM-END is non-nil, the reduction occurs from the back of
+the SEQ moving forward, and the order of arguments to the
+FUNCTION is also reversed.
+
 \n(fn FUNCTION SEQ [KEYWORD VALUE]...)"
   (cl--parsing-keywords (:from-end (:start 0) :end :initial-value :key) ()
     (or (listp cl-seq) (setq cl-seq (append cl-seq nil)))