Add helpful (with custom forward and back functions)

init.el

@@ -40,15 +40,15 @@
 
 ;; basic stuff
 (use-package emacs
-  :hook ((emacs-lisp-mode . my/-emacs-lisp-mode-setup-evil-lookup)
+  :hook (;(emacs-lisp-mode . my/-emacs-lisp-mode-setup-evil-lookup)
          (prog-mode . electric-pair-local-mode)
          ((text-mode message-mode tex-mode) . flyspell-mode)
-         ((text-mode message-mode tex-mode) . auto-fill-mode)
+         ((text-mode message-mode tex-mode prog-mode) . auto-fill-mode)
          (prog-mode . flyspell-prog-mode))
   :init
-  (defun my/-emacs-lisp-mode-setup-evil-lookup ()
+  ;; (defun my/-emacs-lisp-mode-setup-evil-lookup ()
-    (setq-local evil-lookup-func
+  ;;   (setq-local evil-lookup-func
-                #'my/describe-symbol-at-point))
+  ;;               #'my/describe-symbol-at-point))
   (defun my/describe-symbol-at-point ()
     "Calls `describe-symbol' on the return value of `form-at-point'."
     (interactive)
@@ -108,7 +108,8 @@
 
   ;; Some settings for programming
   (setq-default indent-tabs-mode nil
-		        tab-width 4)
+		        tab-width 4
+                fill-column 80)
 
   ;; Tree sitter download locations
   (setq treesit-language-source-alist
@@ -313,7 +314,9 @@ visual states."
   :bind (("C-," . embark-act)
          ("C-;" . embark-dwim)
          :map help-map
-         ("B" . embark-bindings))
+         ("B" . embark-bindings)
+         :map embark-symbol-map
+         ("h" . helpful-symbol))
   :init
   (setq embark-quit-after-action nil)
   (add-to-list 'display-buffer-alist
@@ -500,8 +503,9 @@ visual states."
 
 ;; yasnippet
 (use-package yasnippet
+  :demand t
   :bind ("C-c s" . yas-expand)
-  :init
+  :config
   (yas-global-mode 1))
 
 ;; project.el
@@ -1154,6 +1158,91 @@ If no name is given, list all bookmarks instead."
 (mu4e t)
 (mu4e-context-switch nil "Personal")
 
+;; helpful
+(use-package helpful
+  :hook (emacs-lisp-mode . my/-helpful-setup-emacs-lisp-mode)
+  :bind (:map help-map
+         ("f" . helpful-callable)
+         ("v" . helpful-variable)
+         ("k" . helpful-key)
+         ("x" . helpful-command)
+         ("F" . helpful-function)
+         :map helpful-mode-map
+         ("<normal-state><" . my/helpful-history-back)
+         ("<normal-state>>" . my/helpful-history-forward))
+  :init
+  (defun my/-helpful-setup-emacs-lisp-mode ()
+    (setq-local evil-lookup-func #'helpful-at-point))
+  (defvar my/helpful-symbol-history-size 20
+    "Max size of `my/helpful-symbol-history'.")
+  (defvar my/helpful-symbol-history '()
+    "History of helpful symbols.")
+  (defun my/helpful-history-back (count)
+    "Go back COUNT symbols in `my/helpful-symbol-history'.  If called
+interactively, COUNT defaults to 1."
+    (interactive "p")
+    (my/helpful-history-forward (- count)))
+  (defun my/helpful-history-forward (count)
+    "Move COUNT symbols in `my/helpful-symbol-history'.  If COUNT is negative,
+move back.  If COUNT is larger than the history, go to the newest entry. Go to
+the oldest entry if -COUNT is larger than the history."
+    (interactive "p")
+    (when helpful--sym
+      (let* ((hist-len (length my/helpful-symbol-history))
+             (current-pos (seq-position my/helpful-symbol-history
+                                        (cons helpful--sym
+                                              helpful--callable-p)
+                                        'equal))
+             (new-pos (- current-pos count)))
+        (cond
+         ;; if already at the newest element, signal an error
+         ((and (> count 0) (= current-pos 0))
+          (message "%s" "No newer symbol!"))
+         ;; if already at the oldest element, signal an error
+         ((and (< count 0) (= (1+ current-pos) hist-len))
+          (message "%s" "No older symbol!"))
+         (t
+          (let ((entry (cond
+                        ((<= new-pos 0)
+                         (seq-first my/helpful-symbol-history))
+                        ((>= new-pos hist-len)
+                         (car (last my/helpful-symbol-history)))
+                        (t
+                         (nth new-pos my/helpful-symbol-history)))))
+            (if (cdr entry)
+                (helpful-callable (car entry))
+              (helpful-variable (car entry)))))))))
+  (defun my/-helpful-switch-buffer-function (helpful-buf)
+    "Like `pop-to-buffer', but kill previous helpful buffers and save the new
+buffers `helpful--sym' to `my/helpful-symbol-history'."
+    (cl-loop for buf in (buffer-list)
+             with window = nil
+             with last-index = nil
+             when (and
+                   (not (eq buf helpful-buf))
+                   (eq (buffer-local-value 'major-mode buf) 'helpful-mode))
+             do
+             (when-let (cur-window (get-buffer-window buf nil))
+               (setq window cur-window))
+             (when-let (entry (buffer-local-value 'helpful--sym buf))
+               (setq last-index (seq-position my/helpful-symbol-history entry 'equal)))
+             (kill-buffer buf)
+             finally
+             (when-let ((entry (cons (buffer-local-value 'helpful--sym helpful-buf)
+                                     (buffer-local-value 'helpful--callable-p
+                                                         helpful-buf)))
+                        ((not (seq-contains-p my/helpful-symbol-history entry 'equal))))
+               (when last-index
+                 (setq my/helpful-symbol-history
+                       (seq-drop my/helpful-symbol-history last-index)))
+               (push entry my/helpful-symbol-history)
+               (seq-take my/helpful-symbol-history my/helpful-symbol-history-size))
+             (if window
+                 (window--display-buffer helpful-buf window 'reuse)
+               (pop-to-buffer helpful-buf))))
+  (setq helpful-switch-buffer-function 'my/-helpful-switch-buffer-function
+        helpful-max-buffers 2))
+
 ;; rainbow-delimiters
 (use-package rainbow-delimiters
   :hook (prog-mode . rainbow-delimiters-mode))