module Lib (mainish) where import Data.IORef (IORef, newIORef) import GHC.Debugger.View.Class newtype ColonList = ColonList (IORef [String]) instance Show ColonList where show _ = "" instance DebugView ColonList where debugValue _ = simpleValue "This is an IORef!" False debugFields _ = pure (VarFields []) mainish :: IO () mainish = do value <- mkValue print value mkValue :: IO ColonList mkValue = ColonList <$> newIORef ["alpha", "beta", "gamma"]