• Use GHC 8.3, not GHC 7. Not sure why 7 is enabled, let me try and disable it.

  • I got this error when running the tests.

        Not in scope: `main'
        Perhaps you meant `min' (imported from Prelude)

    I modified it, by adding

    main :: IO ()
    main = hspec spec

    And then the basic test runs normally.
    But when I want to attampt to the final tests. The same error occurs.