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Diffstat (limited to 'lisp/emacs-lisp/seq.el')
| -rw-r--r-- | lisp/emacs-lisp/seq.el | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/lisp/emacs-lisp/seq.el b/lisp/emacs-lisp/seq.el index f0dc283f57d..b7dcde87f41 100644 --- a/lisp/emacs-lisp/seq.el +++ b/lisp/emacs-lisp/seq.el @@ -467,6 +467,17 @@ negative integer or 0, nil is returned." (setq sequence (seq-drop sequence n))) (nreverse result)))) +(cl-defgeneric seq-union (sequence1 sequence2 &optional testfn) + "Return a list of all elements that appear in either SEQUENCE1 or SEQUENCE2. +Equality is defined by TESTFN if non-nil or by `equal' if nil." + (let ((accum (lambda (acc elt) + (if (seq-contains-p acc elt testfn) + acc + (cons elt acc))))) + (seq-reverse + (seq-reduce accum sequence2 + (seq-reduce accum sequence1 '()))))) + ;;;###autoload (cl-defgeneric seq-intersection (sequence1 sequence2 &optional testfn) "Return a list of the elements that appear in both SEQUENCE1 and SEQUENCE2. |