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If I add up all the phone numbers I get from pretty ladies to ensure it comes to a given total, is that a... "chick sum"?
Luhn still checks out:
luhn :: [Int] -> Int
luhn digits = flip mod 10 $ sum $ zipWith (*) (cycle [1,2]) digits
chicksum :: [[Int]] -> Bool
chicksum ds = 0 == sum $ luhn <$> ds
Lol jk I don't get anyone's phone number :(