Function: seq-difference

seq-difference is a byte-compiled function defined in seq.el.gz.

Signature

(seq-difference SEQUENCE1 SEQUENCE2 &optional TESTFN)

Documentation

Return list of all the elements that appear in SEQUENCE1 but not in SEQUENCE2.

"Equality" of elements is defined by the function TESTFN, which
defaults to equal.

Other relevant functions are documented in the sequence group.

View in manual

Shortdoc

;; sequence
(seq-difference '(1 2 3) '(2 3 4))
    => (1)

Aliases

ediff-set-difference (obsolete since 28.1)

Implementations

(seq-difference SEQUENCE1 SEQUENCE2 &optional TESTFN) in `seq.el'.

Undocumented

Source Code

;; Defined in /usr/src/emacs/lisp/emacs-lisp/seq.el.gz
(cl-defgeneric seq-difference (sequence1 sequence2 &optional testfn)
  "Return list of all the elements that appear in SEQUENCE1 but not in SEQUENCE2.
\"Equality\" of elements is defined by the function TESTFN, which
defaults to `equal'."
  (seq-reduce (lambda (acc elt)
                (if (seq-contains-p sequence2 elt testfn)
                    acc
                  (cons elt acc)))
              (seq-reverse sequence1)
              '()))