Add new function `seq-split'

* doc/lispref/sequences.texi (Sequence Functions): Document it.

* lisp/emacs-lisp/seq.el (seq-split): New function.

* lisp/emacs-lisp/shortdoc.el (sequence): Mention it.

1 files changed, 21 insertions, 0 deletions

diff --git a/test/lisp/emacs-lisp/seq-tests.el b/test/lisp/emacs-lisp/seq-tests.el
index 9e5d59163f9..d979604910e 100644
--- a/test/lisp/emacs-lisp/seq-tests.el
+++ b/test/lisp/emacs-lisp/seq-tests.el
@@ -511,5 +511,26 @@ Evaluate BODY for each created sequence.
     (should (equal (seq-difference '(1 nil) '(2 nil))
                    '(1)))))
 
+(ert-deftest test-seq-split ()
+  (let ((seq [0 1 2 3 4 5 6 7 8 9 10]))
+    (should (equal seq (car (seq-split seq 20))))
+    (should (equal seq (car (seq-split seq 11))))
+    (should (equal (seq-split seq 10)
+                   '([0 1 2 3 4 5 6 7 8 9] [10])))
+    (should (equal (seq-split seq 5)
+                   '([0 1 2 3 4] [5 6 7 8 9] [10])))
+    (should (equal (seq-split seq 1)
+                   '([0] [1] [2] [3] [4] [5] [6] [7] [8] [9] [10])))
+    (should-error (seq-split seq 0))
+    (should-error (seq-split seq -10)))
+  (let ((seq '(0 1 2 3 4 5 6 7 8 9)))
+    (should (equal (seq-split seq 5)
+                   '((0 1 2 3 4) (5 6 7 8 9)))))
+  (let ((seq "0123456789"))
+    (should (equal (seq-split seq 2)
+                   '("01" "23" "45" "67" "89")))
+    (should (equal (seq-split seq 3)
+                   '("012" "345" "678" "9")))))
+
 (provide 'seq-tests)
 ;;; seq-tests.el ends here