Either "GHCi as a daemon" or "GHC + a bit of an IDE". A very simple Haskell
development tool which shows you the errors in your project and updates them
whenever you save. Run 'ghcid --command=ghci', where '--command' is the
command to start GHCi on your project (defaults to 'ghci' if you have a '.ghci'
file, or else to 'cabal repl').
