emacs: Add and use alist accessors.

* emacs/guix-utils.el (guix-define-alist-accessor): New macro.
  (guix-assq-value, guix-assoc-value): New functions.
  (guix-get-key-val): Remove.
* emacs/guix-base.el: Replace 'guix-get-key-val' with 'guix-assq-value'
  everywhere.
* emacs/guix-info.el: Likewise.
* emacs/guix-list.el: Likewise.
* emacs/guix-messages.el: Likewise.

1 files changed, 19 insertions, 8 deletions

diff --git a/emacs/guix-utils.el b/emacs/guix-utils.el
index 0b8a760af8..78ea3545c6 100644
--- a/emacs/guix-utils.el
+++ b/emacs/guix-utils.el
@@ -193,14 +193,6 @@ Return time value."
   (require 'org)
   (org-read-date nil t nil prompt))
 
-(defun guix-get-key-val (alist &rest keys)
-  "Return value from ALIST by KEYS.
-ALIST is alist of alists of alists ... which can be consecutively
-accessed with KEYS."
-  (let ((val alist))
-    (dolist (key keys val)
-      (setq val (cdr (assq key val))))))
-
 (defun guix-find-file (file)
   "Find FILE if it exists."
   (if (file-exists-p file)
@@ -224,6 +216,25 @@ Return nil otherwise."
         (guix-any pred (cdr lst)))))
 
 
+;;; Alist accessors
+
+(defmacro guix-define-alist-accessor (name assoc-fun)
+  "Define NAME function to access alist values using ASSOC-FUN."
+  `(defun ,name (alist &rest keys)
+     ,(format "Return value from ALIST by KEYS using `%s'.
+ALIST is alist of alists of alists ... which can be consecutively
+accessed with KEYS."
+              assoc-fun)
+     (if (or (null alist) (null keys))
+         alist
+       (apply #',name
+              (cdr (,assoc-fun (car keys) alist))
+              (cdr keys)))))
+
+(guix-define-alist-accessor guix-assq-value assq)
+(guix-define-alist-accessor guix-assoc-value assoc)
+
+
 ;;; Diff
 
 (defvar guix-diff-switches "-u"