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Diffstat (limited to 'lisp/subr.el')
| -rw-r--r-- | lisp/subr.el | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/lisp/subr.el b/lisp/subr.el index ca184d8fc81..c1d90e3fb18 100644 --- a/lisp/subr.el +++ b/lisp/subr.el @@ -555,6 +555,12 @@ If N is omitted or nil, remove the last element." (declare (compiler-macro (lambda (_) `(= 0 ,number)))) (= 0 number)) +(defun proper-list-p (object) + "Return OBJECT's length if it is a proper list, nil otherwise. +A proper list is neither circular nor dotted (i.e., its last cdr +is nil)." + (and (listp object) (ignore-errors (length object)))) + (defun delete-dups (list) "Destructively remove `equal' duplicates from LIST. Store the result in LIST and return it. LIST must be a proper list. |