Implement haskell-goto-first-error

doc/haskell-mode.texi

@@ -730,6 +730,21 @@ associated with at most one GHCi session, so when you call
 no session associated yet, you're asked which GHCi session to create or
 associate with.
 
+@section Goto Error
+
+In a Haskell source buffer associated with a GHCi session, errors that
+prevent the file from loading are highlighted with
+@code{haskell-error-face}.  You can move between these error lines with
+
+@table @kbd
+@item M-n
+is bound to @code{haskell-goto-next-error}
+@item M-p
+is bound to @code{haskell-goto-prev-error}
+@item C-c M-p
+is bound to @code{haskell-goto-first-error}
+@end table
+
 @section Using GHCi-ng
 
 Put @code{:set +c} in your @code{.ghci} or run it in the REPL. Then use

haskell-load.el

@@ -346,6 +346,12 @@ correspondingly-named overlay properties of OVL."
 	(t
 	 (message "No further notes from Haskell compiler."))))
 
+(defun haskell-goto-first-error ()
+  (interactive)
+  (haskell-goto-error-overlay
+   (first-overlay-in-if 'haskell-check-overlay-p
+                        (buffer-end 0) (buffer-end 1))))
+
 (defun haskell-goto-prev-error ()
   (interactive)
   (haskell-goto-error-overlay

haskell.el

@@ -54,6 +54,7 @@
     (define-key map [?\C-c ?\C-z] 'haskell-interactive-switch)
     (define-key map (kbd "M-n") 'haskell-goto-next-error)
     (define-key map (kbd "M-p") 'haskell-goto-prev-error)
+    (define-key map (kbd "C-c M-p") 'haskell-goto-first-error)
     map)
   "Keymap for using haskell-interactive-mode.")
 

tests/haskell-load-tests.el

@@ -0,0 +1,85 @@
+;;; haskell-load-tests.el
+
+;;; Code:
+
+(require 'ert)
+(require 'haskell-test-utils)
+
+(require 'haskell-load)
+
+(defun insert-errors ()
+  (insert "import Control.Applicativ\nimport Data.Mayb\nimport Data.String")
+  (goto-char 1)
+  (let ((applicativ (progn
+                      (search-forward "Control.Applicativ")
+                      (make-overlay (match-beginning 0) (match-end 0)))))
+    (overlay-put applicativ 'haskell-check t)
+    (overlay-put applicativ 'haskell-msg-type 'error)
+    (overlay-put applicativ 'haskell-msg "Could not find module ‘Control.Applicativ’\n    Perhaps you meant Control.Applicative (from base-4.8.1.0)\n    Use -v to see a list of the files searched for."))
+  (let ((mayb (progn
+                (search-forward "Data.Mayb")
+                (make-overlay (match-beginning 0) (match-end 0)))))
+    (overlay-put mayb 'haskell-check t)
+    (overlay-put mayb 'haskell-msg-type 'error)
+    (overlay-put mayb 'haskell-msg "Could not find module ‘Data.Mayb’\n    Perhaps you meant\n      Data.Maybe (from base-4.8.1.0)\n      Data.Map (from containers-0.5.6.2@conta_LKCPrTJwOTOLk4OU37YmeN)\n    Use -v to see a list of the files searched for."))
+  (goto-char 1))
+
+(ert-deftest goto-first-error-before ()
+  (with-temp-switch-to-buffer
+   (insert-errors)
+   (haskell-goto-first-error)
+   (should (looking-at-p "Control.Applicativ"))))
+
+(ert-deftest goto-first-error-after ()
+  (with-temp-switch-to-buffer
+   (insert-errors)
+   (search-forward "Data.String")
+   (haskell-goto-first-error)
+   (should (looking-at-p "Control.Applicativ"))))
+
+(ert-deftest goto-first-error-between ()
+  (with-temp-switch-to-buffer
+   (insert-errors)
+   (search-forward "import Data.Mayb")
+   (haskell-goto-first-error)
+   (should (looking-at-p "Control.Applicativ"))))
+
+(ert-deftest goto-next-error-before ()
+  (with-temp-switch-to-buffer
+   (insert-errors)
+   (haskell-goto-next-error)
+   (should (looking-at-p "Control.Applicativ"))))
+
+(ert-deftest goto-next-error-between ()
+  (with-temp-switch-to-buffer
+   (insert-errors)
+   (search-forward "import" nil nil 2)
+   (haskell-goto-next-error)
+   (should (looking-at-p "Data.Mayb"))))
+
+(ert-deftest goto-next-error-after ()
+  (with-temp-switch-to-buffer
+   (insert-errors)
+   (search-forward "import" nil nil 3)
+   (haskell-goto-next-error)
+   (should (looking-at-p " Data.String"))))
+
+(ert-deftest goto-prev-error-before ()
+  (with-temp-switch-to-buffer
+   (insert-errors)
+   (haskell-goto-prev-error)
+   (should (looking-at-p "import Control.Applicativ"))))
+
+(ert-deftest goto-prev-error-between ()
+  (with-temp-switch-to-buffer
+   (insert-errors)
+   (search-forward "import" nil nil 2)
+   (haskell-goto-prev-error)
+   (should (looking-at-p "Control.Applicativ"))))
+
+(ert-deftest goto-prev-error-after ()
+  (with-temp-switch-to-buffer
+   (insert-errors)
+   (search-forward "import Data.String")
+   (haskell-goto-prev-error)
+   (should (looking-at-p "Data.Mayb"))))