mu4e: small code cleanups

Update some old code (we have 28.1 now); mostly:
- (= (length lst) x) ===> (length== lst x)
- (cdr (assoc ...)) ==> alist-get

8 files changed, 26 insertions, 31 deletions

diff --git a/mu4e/mu4e-bookmarks.el b/mu4e/mu4e-bookmarks.el
index 1bc80e1..edecc31 100644
--- a/mu4e/mu4e-bookmarks.el
+++ b/mu4e/mu4e-bookmarks.el
@@ -1,6 +1,6 @@
 ;;; mu4e-bookmarks.el --- Bookmarks handling -*- lexical-binding: t -*-
 
-;; Copyright (C) 2011-2025 Dirk-Jan C. Binnema
+;; Copyright (C) 2011-2026 Dirk-Jan C. Binnema
 
 ;; Author: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 ;; Maintainer: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
@@ -147,7 +147,7 @@ with KEY."
   "Get `mu4e-bookmarks' in the (new) format.
 Convert from the old format if needed."
   (seq-map (lambda (item)
-             (if (and (listp item) (= (length item) 3))
+             (if (and (listp item) (length= item 3))
                  `(:name  ,(nth 1 item) :query ,(nth 0 item)
                           :key   ,(nth 2 item))
                item))
diff --git a/mu4e/mu4e-contacts.el b/mu4e/mu4e-contacts.el
index 1a63d40..3f7c274 100644
--- a/mu4e/mu4e-contacts.el
+++ b/mu4e/mu4e-contacts.el
@@ -1,6 +1,6 @@
 ;;; mu4e-contacts.el --- Dealing with contacts -*- lexical-binding: t -*-
 
-;; Copyright (C) 2022-2025 Dirk-Jan C. Binnema
+;; Copyright (C) 2022-2026 Dirk-Jan C. Binnema
 
 ;; Author: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 ;; Maintainer: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
@@ -236,7 +236,7 @@ The reverse of the RFC atext definition is then tested. If it
 matches, nil is returned, if not, it returns a symbol
 `rfc822-atom'."
   (cond
-   ((= (length ph) 0) 'rfc822-empty)
+   ((length= ph 0) 'rfc822-empty)
    ((= (aref ph 0) ?\")
     (if (string-match "\"\\([^\"\\\n]\\|\\\\.\\|\\\\\n\\)*\"" ph)
         'rfc822-quoted-string
diff --git a/mu4e/mu4e-contrib.el b/mu4e/mu4e-contrib.el
index 1da3c9b..d763064 100644
--- a/mu4e/mu4e-contrib.el
+++ b/mu4e/mu4e-contrib.el
@@ -1,6 +1,6 @@
 ;;; mu4e-contrib.el --- User-contributed functions -*- lexical-binding: t -*-
 
-;; Copyright (C) 2013-2023 Dirk-Jan C. Binnema
+;; Copyright (C) 2013-2026 Dirk-Jan C. Binnema
 
 ;; This file is not part of GNU Emacs.
 
@@ -155,12 +155,11 @@ the file."
         (bufs nil)
         ;; Remove directories from the list
         (files-to-attach
-         (delq nil (mapcar
-                    (lambda (f) (if (or (not (file-exists-p f))
-                                        (file-directory-p f))
-                                    nil
-                                  (expand-file-name f)))
-                    (mu4e--flatten-list (reverse args))))))
+         (seq-keep
+          (lambda (f) (when (and (file-exists-p f)
+                                (not (file-directory-p f)))
+                        (expand-file-name f)))
+          (mu4e--flatten-list (reverse args)))))
     ;; warn if user tries to attach without any files marked
     (if (null files-to-attach)
         (error "No files to attach")
@@ -173,7 +172,7 @@ the file."
       (if (and bufs
                (y-or-n-p "Attach files to existing mail composition buffer? "))
           (setq destination
-                (if (= (length bufs) 1)
+                (if (length= bufs 1)
                     (get-buffer (car bufs))
                   (let ((prompt (mu4e-format "%s" "Attach to buffer")))
                     (substring-no-properties
diff --git a/mu4e/mu4e-headers.el b/mu4e/mu4e-headers.el
index a383401..3e2346e 100644
--- a/mu4e/mu4e-headers.el
+++ b/mu4e/mu4e-headers.el
@@ -1,6 +1,6 @@
 ;;; mu4e-headers.el --- Message headers -*- lexical-binding: t  -*-
 
-;; Copyright (C) 2011-2025 Dirk-Jan C. Binnema
+;; Copyright (C) 2011-2026 Dirk-Jan C. Binnema
 
 ;; Author: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 ;; Maintainer: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
@@ -1101,7 +1101,7 @@ If THREADS is non-nil, give a more informative error message."
      (mapcar
       (lambda (item)
         (let* ((field (car item)) (width (cdr item))
-               (info (cdr (assoc field fields)))
+               (info (alist-get field fields))
                (sortable-info (plist-get info :sortable))
                ;; the effective sort-field for this field is as per its info;
                ;; if t, it's the field itself; otherwise it's either some
diff --git a/mu4e/mu4e-icalendar.el b/mu4e/mu4e-icalendar.el
index 82a18f8..ae2e694 100644
--- a/mu4e/mu4e-icalendar.el
+++ b/mu4e/mu4e-icalendar.el
@@ -1,6 +1,7 @@
 ;;; mu4e-icalendar.el --- iCalendar & diary integration -*- lexical-binding: t; -*-
 
-;; Copyright (C) 2019-2023 Christophe Troestler
+;; Copyright (C) 2019-2026 Christophe Troestler
+;; Copyright (C) 2019-2026 Dirk-Jan C. Binnema
 
 ;; Author: Christophe Troestler <Christophe.Troestler@umons.ac.be>
 ;; Maintainer: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
@@ -106,7 +107,7 @@
                  (gnus-icalendar-event-reply-from-buffer
                   (current-buffer) status (gnus-icalendar-identities))))
          (msg (mu4e-message-at-point 'noerror))
-         (charset (cdr (assoc 'charset (mm-handle-type handle)))))
+         (charset (alist-get 'charset (mm-handle-type handle))))
     (when reply
       (cl-labels
           ((fold-icalendar-buffer
@@ -157,7 +158,7 @@
                 (mu4e--icalendar-insert-diary event status
                                               mu4e-icalendar-diary-file)))))))))
 
-(declare-function mu4e-view-headers-next "mu4e-view")
+
 (defun mu4e--icalendar-trash-message (original-msg)
   "Trash the message ORIGINAL-MSG and move to the next one."
   (lambda (docid path)
@@ -173,15 +174,9 @@
       (when (and (mu4e~headers-view-this-message-p docid)
                  (buffer-live-p (mu4e-get-view-buffer)))
         (mu4e-display-buffer (mu4e-get-view-buffer))
-        (or (mu4e-view-headers-next)
+        (or (mu4e-headers-next)
             (kill-buffer-and-window))))))
 
-;; (defun mu4e--icalendar-trash-message-hook (original-msg)
-;;   "Trash the iCalendar message ORIGINAL-MSG."
-;;   (lambda ()
-;;     (setq mu4e-sent-func
-;;           (mu4e--icalendar-trash-message original-msg))))
-
 (defun mu4e--icalendar-insert-diary (event reply-status filename)
   "Insert a diary entry for the EVENT in file named FILENAME.
 REPLY-STATUS is the status of the reply.  The possible values are
diff --git a/mu4e/mu4e-search.el b/mu4e/mu4e-search.el
index 3ef3c38..d694b65 100644
--- a/mu4e/mu4e-search.el
+++ b/mu4e/mu4e-search.el
@@ -1,6 +1,6 @@
 ;;; mu4e-search.el --- Search-related functions -*- lexical-binding: t -*-
 
-;; Copyright (C) 2021-2025 Dirk-Jan C. Binnema
+;; Copyright (C) 2021-2026 Dirk-Jan C. Binnema
 
 ;; Author: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 ;; Maintainer: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
@@ -480,7 +480,7 @@ by the `:date' field."
          ;; note: 'sortable' is either a boolean (meaning: if non-nil, this is
          ;; sortable field), _or_ another field (meaning: sort by this other
          ;; field).
-         (sortable (plist-get (cdr (assoc field mu4e-header-info)) :sortable))
+         (sortable (plist-get (alist-get field mu4e-header-info) :sortable))
          ;; error check
          (sortable
           (if sortable
diff --git a/mu4e/mu4e-thread.el b/mu4e/mu4e-thread.el
index 2f093b8..1a94fe8 100644
--- a/mu4e/mu4e-thread.el
+++ b/mu4e/mu4e-thread.el
@@ -1,6 +1,7 @@
 ;;; mu4e-thread.el --- Thread folding support -*- lexical-binding: t -*-
 
 ;; Copyright (C) 2023 Nicolas P. Rougier
+;; Copyright (C) 2023-2026 Dirk-Jan C. Binnema
 
 ;; Author: Nicolas P. Rougier <Nicolas.Rougier@inria.fr>
 ;; Keywords: mail
@@ -161,7 +162,7 @@ Reset individual folding states."
       (while (not (eobp))
         (when-let* ((msg (get-text-property (point) 'msg))
                     (docid (mu4e-message-field msg :docid))
-                    (state (cdr (assoc docid mu4e-thread--docids))))
+                    (state (alist-get docid mu4e-thread--docids)))
           (if (eq state 'folded)
               (mu4e-thread-fold)
             (mu4e-thread-unfold)))
diff --git a/mu4e/mu4e-view.el b/mu4e/mu4e-view.el
index 59951ce..ef685b7 100644
--- a/mu4e/mu4e-view.el
+++ b/mu4e/mu4e-view.el
@@ -235,7 +235,7 @@ any further, go the next message."
       (scroll-up)
     (error
      (when mu4e-view-scroll-to-next
-       (mu4e-view-headers-next)))))
+       (mu4e-headers-next)))))
 
 (defun mu4e-scroll-up ()
   "Scroll text of selected window up one line."
@@ -716,7 +716,7 @@ render.  After inserting, highlight the headers."
 
 (defun mu4e--view-gnus-insert-header (field val)
   "Insert a header FIELD with value VAL."
-  (let* ((info (cdr (assoc field mu4e-header-info)))
+  (let* ((info (alist-get field mu4e-header-info))
          (key (or (plist-get info :name)
                   ;; Fallback for fields not in mu4e-header-info
                   ;; (e.g. :user-agent): derive from the keyword name.
@@ -728,8 +728,8 @@ render.  After inserting, highlight the headers."
 
 (defun mu4e--view-gnus-insert-header-custom (msg field)
   "Insert MSG's custom FIELD."
-  (let* ((info (cdr-safe (or (assoc field mu4e-header-info-custom)
-                             (mu4e-error "Custom field %S not found" field))))
+  (let* ((info (or (alist-get field mu4e-header-info-custom)
+                   (mu4e-error "Custom field %S not found" field)))
          (key (plist-get info :name))
          (func (or (plist-get info :function)
                    (mu4e-error "No :function defined for custom field %S %S"