input.hs

{-# LANGUAGE PatternSynonyms #-}

module Foo (
  asdf,
  bar,
) where

data Test
  = Test1
      { a :: Int,
        b :: Int
      }
  | Test2 Bool

x :: IO Int
x = do
  putStrLn "asdf"
  let result =
        y + 10
  return result
  where
    y = 1

class Foo a where
  foo :: a -> Int

pattern HeadC x <- x : xs
  where
    HeadC x = [x]