LensSkolem.hs

{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE RankNTypes #-}

module Main where

import Control.Lens

data Game = Game { _player1 :: String } deriving (Show)

makeLenses ''Game

game = Game { _player1 = "Bob" }

main :: IO () 
main = showElder 

showElder :: IO ()
showElder = 
  -- showPlayer $ const player1 $ ()  -- OK
  showPlayer . (const player1) $ ()  -- NOK

showPlayer :: Lens' Game String -> IO ()
showPlayer playerLens = print $ game ^. playerLens