(defmacro wg-dbind (args expr &rest body)

  "Bind the variables in ARGS to the result of EXPR and execute BODY.

Abbreviation of `destructuring-bind'."

  (declare (indent 2))

  `(cl-destructuring-bind ,args ,expr ,@body))

(defun wg-partition (list &optional n step)

  "Take LIST, return a list of N length sublists, offset by STEP.

N defaults to 2, and STEP defaults to N.

Iterative to prevent stack overflow."

  (let* ((n (or n 2)) (step (or step n)) acc)

    (while list

      (setq list (nthcdr step list)))

    (nreverse acc)))

;;; bindings

(defmacro wg-when-let (binds &rest body)

  "Like `let*' but when all BINDS are non-nil - eval BODY."

  (declare (indent 1))

  (wg-dbind (bind . binds) binds

    (when (consp bind)

(defmacro wg-removef-p (item seq-place &rest keys)

  "If ITEM is a `member*' of SEQ-PLACE, remove it from SEQ-PLACE and return t.

Otherwise return nil.  KEYS can be any keywords accepted by `remove*'."

  `(> (length ,seq-place)

      (length (setf ,seq-place (cl-remove ,item ,seq-place ,@keys)))))

(defmacro wg-pushnew-p (item seq-place &rest keys)

  "If ITEM is not a `member' of SEQ-PLACE, push it to SEQ-PLACE and return t.

Otherwise return nil.  KEYS can be any keyword args accepted by `pushnew'."

  `(< (length ,seq-place)

      (length (cl-pushnew ,item ,seq-place ,@keys))))

(defun wg-range (start end)

  "Return a list of integers from START up to but not including END."

  (let (accum)

    (dotimes (i (- end start) (nreverse accum))

      (push (+ start i) accum))))

(defun wg-rotate-list (list &optional offset)

  "Rotate LIST by OFFSET.  Positive OFFSET rotates left, negative right."

  (when list

    (let ((split (mod (or offset 1) (length list))))

(defun wg-center-rotate-list (list)

  "Rotate LIST so it's first elt is in the center.  When LIST's

length is even, the first elt is left nearer the front."

  (wg-rotate-list list (- (/ (1- (length list)) 2))))

(defun wg-insert-after (elt list index)

  "Insert ELT into LIST after INDEX."

  (let ((new-list (cl-copy-list list)))

    (push elt (cdr (nthcdr index new-list)))

    new-list))