haskell-sort-imports: do not modify buffer if imports are already sorted

Author: bos

haskell-sort-imports.el

@@ -53,18 +53,19 @@ within that region."
           (progn (goto-char (region-beginning))
                  (haskell-sort-imports-goto-import-start))
         (haskell-sort-imports-goto-group-start))
-      (let ((start (point))
-            (imports (haskell-sort-imports-collect-imports)))
-        (delete-region start (point))
-        (mapc (lambda (import)
-                (insert import "\n"))
-              (sort imports (lambda (a b)
-                              (string< (haskell-sort-imports-normalize a)
-                                       (haskell-sort-imports-normalize b)))))
-        (goto-char start)
-        (when (search-forward current-string nil t 1)
-          (forward-char (- (length current-string)))
-          (forward-char current-offset))))))
+      (let* ((start (point))
+	     (imports (haskell-sort-imports-collect-imports))
+	     (sorted (sort (copy-list imports)
+			   (lambda (a b)
+			     (string< (haskell-sort-imports-normalize a)
+				      (haskell-sort-imports-normalize b))))))
+	(when (not (equal imports sorted))
+	  (delete-region start (point))
+	  (mapc (lambda (import) (insert import "\n")) sorted))
+	(goto-char start)
+	(when (search-forward current-string nil t 1)
+	  (forward-char (- (length current-string)))
+	  (forward-char current-offset))))))
 
 (defun haskell-sort-imports-normalize (i)
   "Normalize an import, if possible, so that it can be sorted."