Sample Haskell .ghci template

.ghci

-- Turn off output for resource usage and types.  This is to reduce verbosity when reloading this file.
:unset +s +t
-- Turn on multi-line input and remove the distracting verbosity.
:set +m -v0
-- Turn off all compiler warnings and turn on OverloadedStrings for interactive input.
:seti -w -XOverloadedStrings
-- Set the preferred editor for use with the :e command. I would recommend using an editor in a separate terminal, and using :r to reload, but :e can still be useful for quick edits from within GHCi.
:set editor vim

:def! hoogle \x -> return $ ":!hoogle --color \"" ++ x ++ "\""
:def! doc \x -> return $ ":!hoogle --info --color \"" ++ x ++ "\""

:set -fwarn-unused-binds -fwarn-unused-imports
:set -isrc

:set -package directory

:{
dotGHCI_myPrompt promptString ms _ = do
  -- Get the current directory, replacing $HOME with a '~'.
  pwd <- getpwd
  -- Determine which is the main module.
  let main_module = head' [ m' | (m:m') <- ms, m == '*' ]
  -- Put together the final prompt string.
  -- ANSI escape sequences allow for displaying colours in compatible terminals.  See [http://www.lihaoyi.com/post/BuildyourownCommandLinewithANSIescapecodes.html this guide] for help interpreting them.
  return $ concat [ "\ESC[33m\STX", pwd, main_module, "\ESC[37m\STX", promptString, " \ESC[0m\STX" ]
  where
    head' (x:_) = " \ESC[38;5;227m\STX" ++ x
    head' _     = ""
    getpwd = getpwd' <$> (System.Environment.getEnv "HOME") <*> System.Directory.getCurrentDirectory
    getpwd' home pwd = if zipWith const pwd home == home
                         then '~':drop (length home) pwd
                         else pwd
:}

:set prompt-function dotGHCI_myPrompt "\ESC[38;5;129m\STX\xe61f"
:set prompt-cont-function dotGHCI_myPrompt "∷"

:set -package pretty-show -package hscolour

import qualified Language.Haskell.HsColour as HSC
import qualified Language.Haskell.HsColour.Colourise as HSC

:{
dotGHCI_myPrint :: (Show a) => a -> IO ()
dotGHCI_myPrint a = putStrLn $ HSC.hscolour HSC.TTY myColourPrefs False False "" False $ Text.Show.Pretty.ppShow a
  where
    myColourPrefs = HSC.defaultColourPrefs -- { HSC.conop    = [HSC.Foreground HSC.Yellow]
                                           -- , HSC.conid    = [HSC.Foreground HSC.Yellow, HSC.Bold]
                                           -- , HSC.string   = [HSC.Foreground $ HSC.Rgb 29 193 57]
                                           -- , HSC.char     = [HSC.Foreground HSC.Cyan]
                                           -- , HSC.number   = [HSC.Foreground $ HSC.Rgb 202 170 236]
                                           -- , HSC.keyglyph = [HSC.Foreground HSC.Yellow]
                                           -- }
:}

:seti -interactive-print dotGHCI_myPrint
:def! pretty \_ -> return ":set -interactive-print dotGHCI_myPrint"
:def! nopretty \_ -> return ":set -interactive-print System.IO.print"

:m -Language.Haskell.HsColour
:m -Language.Haskell.HsColour.Colourise

-- Use :rr to reload this file.
:def! rr \_ -> return ":script ~/.ghci"
-- Turn on output of types.  This line should be last.
:set +s +t