main must have type IO a. Hoogle tells me that to convert [IO a] -> IO [a],
you should use the function sequence. Try applying that to your final line.
On Mon, 9 Mar 2015 16:07 Geoffrey Bays
My main function looks like this:
main :: [IO()] main = do let stud1 = Student {name = "Geoff", average = -99.0, grades = [66,77,88]} let stud2 = Student {name = "Doug", average = -99.0, grades = [77,88,99]} let stud3 = Student {name = "Ron", average = -99.0, grades = [55,66,77]} let studList = [stud1,stud2] let newList = calcAvg studList [putStrLn $ show s | s <- newList] --putStrLn $ show (newList !! 0) --putStrLn $ show (newList !! 1)
With this final line, putStrLn $ show (newList !! 0), the type IO () in the function declaration compiles fine. But with [putStrLn $ show s | s <- newList] as the final line, [IO ()] in the function declaration will not compile, I get this error:
Couldn't match expected type `IO t0' with actual type `[IO ()]'
What does the declared type need to be for a final line of: [putStrLn $ show s | s <- newList] ???
Thanks,
Geoffrey
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