I'm weird, so I made a haskell script to generate my ghci config.

gen_ghci_conf.hs

#!stack runhaskell
import Data.Monoid
import Text.Printf

data ExtsHelper
    = Prefixed String
               [ExtsHelper]
    | Values [String]

exts :: [ExtsHelper]
exts =
    [ Prefixed "Overloaded" [Values ["Strings", "Lists"]]
    , Prefixed
          "Derive"
          [ Values
                [ "Functor"
                , "Generic"
                , "Traversable"
                , "Foldable"
                , "DataTypeable"
                ]
          ]
    , Prefixed "Flexible" [Values ["Instances", "Contexts"]]
    , Prefixed "Type" [Values ["SynonymInstances", "Operators", "Families"]]
    , Values
          [ "ExistentialQuantification"
          , "FunctionalDependencies"
          , "RankNTypes"
          , "LambdaCase"
          , "TupleSections"
          , "MultiParamTypeClasses"
          , "MultiWayIf"
          , "NamedFieldPuns"
          , "RecordWildCards"
          , "PartialTypeSignatures"
          , "QuasiQuotes"
          , "TemplateHaskell"
          , "ScopedTypeVariables"
          , "StandaloneDeriving"
          , "GADTs"
          , "ViewPatterns"
          ]
    ]

flattenExts :: ExtsHelper -> [String]
flattenExts (Prefixed p vals) = vals >>= map (p <>) . flattenExts
flattenExts (Values v) = v

main :: IO ()
main =
    writeFile ".ghci" $
    printf
        ":set %v\n:set prompt \"λ>\"\n"
        (unwords $ map ("-X" <>) $ concatMap flattenExts exts)