diff options
Diffstat (limited to 'configs/shared/.emacs.d/wpc/cycle.el')
| -rw-r--r-- | configs/shared/.emacs.d/wpc/cycle.el | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/configs/shared/.emacs.d/wpc/cycle.el b/configs/shared/.emacs.d/wpc/cycle.el index d469ee34c705..9475ddd99659 100644 --- a/configs/shared/.emacs.d/wpc/cycle.el +++ b/configs/shared/.emacs.d/wpc/cycle.el @@ -75,6 +75,19 @@ (nth i (cycle-xs cycle)) nil))) +;; TODO: Consider adding "!" to the function name herein since many of them +;; mutate the collection, and the APIs are beginning to confuse me. +(defun cycle/focus-previous! (xs) + "Jump to the item in XS that was most recently focused; return the cycle. +This will error when previous-index is nil. This function mutates the +underlying struct." + (let ((i (cycle-previous-index xs))) + (if (maybe/some? i) + (progn + (cycle/jump i xs) + (cycle/current xs)) + (error "Cannot focus the previous element since cycle-previous-index is nil")))) + (defun cycle/next (xs) "Return the next value in `XS' and update `current-index'." (let* ((current-index (cycle-current-index xs)) @@ -135,7 +148,8 @@ (prelude/assert (= 1 (->> xs (cycle/jump 0) cycle/current))) (prelude/assert (= 2 (->> xs (cycle/jump 1) cycle/current))) (prelude/assert (= 3 (->> xs (cycle/jump 2) cycle/current))) - (prelude/assert (= 2 (cycle/previous-focus xs))))) + (prelude/assert (= 2 (cycle/previous-focus xs))) + (prelude/assert (= 2 (cycle/focus-previous! xs))))) (provide 'cycle) ;;; cycle.el ends here |