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{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
{-# OPTIONS_GHC -Wall #-}
module Test25 where
import Control.Lens
import Data.Generics.Product
import GHC.Generics
data Record1 = Record1
{ field1 :: Int
, field2 :: Double
} deriving (Generic)
class Default a where
def :: a
instance Default Record1 where
def = Record1 0 0.0
f :: Record1 -> Int
f r = r ^. field @"field1"
main :: IO ()
main = do
print $ f def
print $ f ( field @"field1" .~ 1 $ (def :: Record1))
print $ f ( field @"field1" .~ 2 $ Record1 0 0.0)
print $ f ( field @"field1" .~ (1 :: Int) $ def)
print $ f ( position @1 .~ (1 :: Int) $ def)
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