Add new function `seq-remove-at-position'

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

* lisp/emacs-lisp/seq.el (seq-remove-at-position): New function.

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

* test/lisp/emacs-lisp/seq-tests.el (test-seq-remove-at-position):
Test it.

2 files changed, 17 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/seq.el b/lisp/emacs-lisp/seq.el
index b5f762ef3ac..64197b55e5f 100644
--- a/lisp/emacs-lisp/seq.el
+++ b/lisp/emacs-lisp/seq.el
@@ -347,6 +347,20 @@ list."
               sequence))
 
 ;;;###autoload
+(cl-defgeneric seq-remove-at-position (sequence n)
+  "Return a copy of SEQUENCE where the element at N got removed.
+
+N is the (zero-based) index of the element that should not be in
+the result.
+
+The result is a sequence of the same type as SEQUENCE."
+  (seq-concatenate
+   (let ((type (type-of sequence)))
+     (if (eq type 'cons) 'list type))
+   (seq-subseq sequence 0 n)
+   (seq-subseq sequence (1+ n))))
+
+;;;###autoload
 (cl-defgeneric seq-reduce (function sequence initial-value)
   "Reduce the function FUNCTION across SEQUENCE, starting with INITIAL-VALUE.
 
diff --git a/lisp/emacs-lisp/shortdoc.el b/lisp/emacs-lisp/shortdoc.el
index 990dabe351a..6a366ec0fc0 100644
--- a/lisp/emacs-lisp/shortdoc.el
+++ b/lisp/emacs-lisp/shortdoc.el
@@ -888,6 +888,9 @@ A FUNC form can have any number of `:no-eval' (or `:no-value'),
    :eval (seq-filter #'numberp '(a b 3 4 f 6)))
   (seq-remove
    :eval (seq-remove #'numberp '(1 2 c d 5)))
+  (seq-remove-at-position
+   :eval (seq-remove-at-position '(a b c d e) 3)
+   :eval (seq-remove-at-position [a b c d e] 0))
   (seq-group-by
    :eval (seq-group-by #'cl-plusp '(-1 2 3 -4 -5 6)))
   (seq-union