This isn't an article about how to use a Haskell CSV parser. If it was, it would be about the cassava package, http://hackage.haskell.org/package/cassava

I.e.

    csvfile <- readFile "nukes-list.csv"
    case decode csvfile of
        Left err -> putStrLn err
        Right v -> V.forM_ v $ \ (a,b,c,d) ->
            ...

I don't know why the author didn't just use one of the fine CSV packages on Hackage.