Don't expose the record selector

[josephcsible]

If you expose the record selector, then this program crashes at runtime with a divide by zero error:

import NonZero
safeDivide i (NonZero j) = i `div` j
main = case nonZero 1 of
    Nothing -> putStrLn "One is zero?"
    Just one -> do
        let zero = one{ unNonZero = 0 }
        print $ safeDivide 1 zero

[parsonsmatt]

Great point, thank you! :smile: