diff -r 88c4f68cb191 -r b5976ed7311a elisp/haskell-flycheck.el
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/elisp/haskell-flycheck.el	Wed Feb 04 11:05:42 2015 -0600
@@ -0,0 +1,97 @@
+;;; haskell-flycheck.el --- Flychecker using the GHCi process
+
+;; Copyright (c) 2014 Chris Done. All rights reserved.
+
+;; This file is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3, or (at your option)
+;; any later version.
+
+;; This file is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'haskell-process)
+(require 'flycheck)
+
+(defun flycheck-haskell-process-start (checker callback)
+  "Start a GHCi load with CHECKER.
+
+CALLBACK is the status callback passed by Flycheck."
+  (let ((session (haskell-session)))
+    (haskell-session-current-dir session)
+    (let ((process (haskell-process)))
+      (haskell-process-queue-command
+       process
+       (make-haskell-command
+        :state
+        (list :process process
+              :session session
+              :filename (buffer-file-name)
+              :callback callback
+              :buffer (current-buffer)
+              :original (buffer-string))
+        :go
+        (lambda (state)
+          (with-current-buffer (plist-get state :buffer)
+            (let* ((filename (plist-get state :filename)))
+              (write-region (point-min) (point-max) filename)
+              (clear-visited-file-modtime)
+              (haskell-process-send-string
+               (plist-get state :process)
+               (format ":load \"%s\""
+                       (replace-regexp-in-string
+                        "\""
+                        "\\\\\""
+                        filename))))))
+        :live (lambda (state _)
+                (when (plist-get state :original)
+                  (with-temp-buffer
+                    (insert (plist-get state :original))
+                    (write-region (point-min) (point-max) (plist-get state :filename))
+                    (plist-put state :original nil))))
+        :complete
+        (lambda (state response)
+          (let ((session (plist-get state :session))
+                (process (plist-get state :process)))
+            (haskell-process-set-response-cursor process 0)
+            (let ((errors (list))
+                  (next-error t))
+              (while next-error
+                (setq next-error
+                      (haskell-process-errors-warnings
+                       session
+                       process
+                       response
+                       t))
+                (when (consp next-error)
+                  (add-to-list 'errors
+                               (flycheck-error-new-at
+                                (plist-get next-error :line)
+                                (plist-get next-error :col)
+                                (plist-get next-error :type)
+                                (plist-get next-error :msg)
+                                :checker 'haskell-process
+                                :buffer (plist-get state :buffer)))))
+              (funcall (plist-get state :callback)
+                       'finished
+                       errors)))))))))
+
+
+(flycheck-define-generic-checker 'haskell-process
+  "A syntax and type checker for Haskell using GHCi (via the
+haskell-process Emacs module)."
+  :start 'flycheck-haskell-process-start
+  :modes '(haskell-mode)
+  :next-checkers '((warning . haskell-hlint)))
+
+;; Register as an auto-selectable checker
+(setq flycheck-checkers (cons `haskell-process flycheck-checkers))
+
+(provide 'haskell-flycheck)