# Pastebin M1i564sm
{-# LANGUAGE ApplicativeDo, NamedFieldPuns, RecordWildCards #-}

data Thing = Thing
  { foo :: String
  , bar :: Int
  }

-- | Placeholder
data Parser a deriving (Functor)
instance Applicative Parser where
  pure = undefined
  (<*>) = undefined
-- Note: We don't need a monad instance because of {-# LANGAUGE ApplicativeDo #-}
-- But it works fine with one too

parseFoo :: Parser String
parseFoo = undefined

parseBar :: Parser Int
parseBar = undefined

-- With @-XNamedFieldPuns@:
parseThing :: Parser Thing
parseThing = do
  foo <- parseFoo
  bar <- parseBar
  pure Thing{foo, bar}

-- With @-XRecordWildCards@:
parseThing' :: Parser Thing
parseThing' = do
  foo <- parseFoo
  bar <- parseBar
  pure Thing{..}