Remove sort-onscratch/sort-key

* lisp/sort.el (sort-on):
* doc/lispref/sequences.texi (Sequence Functions):
* etc/NEWS:
Remove the `sort-on` function which is now completely superseded by
the extended `sort` in features, ease of use, and performance.

1 files changed, 0 insertions, 21 deletions

diff --git a/lisp/sort.el b/lisp/sort.el
index 4f0d759ef8a..2ee76b6e1e3 100644
--- a/lisp/sort.el
+++ b/lisp/sort.el
@@ -478,27 +478,6 @@ sRegexp specifying key within record: \nr")
                          ;; if there was no such register
                          (error (throw 'key nil))))))))))
 
-;;;###autoload
-(defun sort-on (sequence predicate accessor)
-  "Sort SEQUENCE by calling PREDICATE on sort keys produced by ACCESSOR.
-SEQUENCE should be the input sequence to sort.
-Elements of SEQUENCE are sorted by keys which are obtained by
-calling ACCESSOR on each element.  ACCESSOR should be a function of
-one argument, an element of SEQUENCE, and should return the key
-value to be compared by PREDICATE for sorting the element.
-PREDICATE is the function for comparing keys; it is called with two
-arguments, the keys to compare, and should return non-nil if the
-first key should sort before the second key.
-The return value is always a new list.
-This function has the performance advantage of evaluating
-ACCESSOR only once for each element in the input SEQUENCE, and is
-therefore appropriate when computing the key by ACCESSOR is an
-expensive operation.  This is known as the \"decorate-sort-undecorate\"
-paradigm, or the Schwartzian transform."
-  (mapcar #'car
-          (sort (mapcar #'(lambda (x) (cons x (funcall accessor x))) sequence)
-                #'(lambda (x y) (funcall predicate (cdr x) (cdr y))))))
-
 
 (defvar sort-columns-subprocess t)