Main.hs

{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TemplateHaskell #-}

module Main where

import Control.Lens
import GHC.Generics

data Foo
  = Foo
  { fooField1 :: Int
  , fooField2 :: Int
  } deriving (Generic, Show)
makeFields ''Foo

data Bar
  = Bar
  { barField1 :: Float
  , barField2 :: Float
  } deriving (Generic, Show)
makeFields ''Bar

main :: IO ()
main = do
  let f = Foo 1 2
  let b = Bar 1 2
  print (view field1 f)
  print (view field1 b)