Deriving without spelling out "deriving"

This GHC plugin automatically adds deriving clauses to all data types in a module.

Example

The following module uses this plugin to derive Eq, Ord, Show for all types by default, excluding invalid instances with the NoDriving option.

{-# LANGUAGE DerivingStrategies #-}
{-# OPTIONS_GHC -fplugin=Driving.Classes #-}

module X where

{-# ANN module (Driving :: Driving
  '[ Stock '(Eq, Ord, Show)
   , NoDriving '(Eq MyEndo, Ord MyEndo, Show MyEndo)
   ]) #-}

data T = C1 | C2
data U = D1 | D2
data V = E1 | E2

newtype MyEndo a = MyEndo (a -> a)