overlays: put a brief overlay summary into the modeline

Author: deepfire

haskell-load.el

@@ -317,9 +317,23 @@ actual Emacs buffer of the module being loaded."
   (let ((ovls (cl-remove-if-not test (overlays-in beg end))))
     (cl-first (sort (cl-copy-list ovls) 'overlay-start>))))
 
+(defun string/starts-with (string prefix)
+  "Return t if STRING starts with prefix."
+  (and (string-match (rx-to-string `(: bos ,prefix) t)
+		     string)
+       t))
+
+(defun haskell-error-overlay-briefly (ovl)
+  (let ((text (overlay-get ovl 'haskell-msg))
+	(type (overlay-get ovl 'haskell-msg-type)))
+    (if (eq type 'warning)
+	(cl-subseq text 13)
+	text)))
+
 (defun haskell-goto-error-overlay (ovl)
   (cond (ovl
-	 (goto-char (overlay-start ovl)))
+	 (goto-char (overlay-start ovl))
+	 (haskell-mode-message-line (haskell-error-overlay-briefly ovl)))
 	(t
 	 (message "No further notes from Haskell compiler."))))
 
@@ -362,6 +376,7 @@ actual Emacs buffer of the module being loaded."
 	(overlay-put ovl 'haskell-check t)
 	(overlay-put ovl 'haskell-file file)
 	(overlay-put ovl 'haskell-msg msg)
+	(overlay-put ovl 'haskell-msg-type type)
 	(overlay-put ovl 'help-echo msg)
 	(overlay-put ovl 'haskell-hole hole)
 	(cl-destructuring-bind (face fringe) (cl-case type