As the original author would start a Haskell file, would turn on all the GHC extensions existing at the time and then proceed to use them. And now I think one or two years have passed, and GHC would no longer compile the sources. They knew what changes they were going to make. They probably even had people who could do the changes, but they did not have – they literally did not have a single person there who could make it compile.
Emphasis mine. Never do this kids.