One reason for the error `The Haskell process `haskell' has died. Restart?'
is that Emacs cannot find the location of the GHCi executable. The
following fix will find this location and add it to the Emacs path.

Note that the solution given is only for OS X / Linux, and it has only
been tested on OS X. Windows installations of Haskell don't seem to have
this problem - if yours does, try the same fix, but with "where" in place
of "which". Also note that any number of problems seem to produce the same
error, so this is not guaranteed to work (but when done correctly seemed
to work for most students at the session on Friday).

  *   Open a terminal.
  *   execute the following command:

which ghci

  *   If you get an error from this command, Haskell has not been installed
      correctly. Otherwise, note the response given (eg. `/opt/local/bin/ghci')
  *   The path that must be added to the Emacs path is the above response,
      but with `/ghci' removed (eg. `/opt/local/bin').
  *   Copy the following two lines to the end of your Emacs config file:

(setenv "PATH" (concat (getenv "PATH") ":HERE"))
(setq exec-path (append exec-path '("HERE")))

  *   Replace HERE with the path described above.
  *   Restart Emacs.

Note that the Emacs config file is usually located at the path `~/.emacs'.
You can also access the Emacs config file by executing the following within
Emacs:

M-: (find-file user-init-file)