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bas080/safe-as-int.hs

Created June 13, 2018 06:19
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safe-as-int.hs
import Data.Char (digitToInt, isDigit)
type Position = Int
safeAsInt :: String -> Either (Position, Char) Int
safeAsInt [] = Right 0
safeAsInt ('-':xs) = fmap negate (safeAsInt xs)
safeAsInt (c:xs)
| isDigit c = fmap (+ (digitToInt c * (10 ^ length xs))) (safeAsInt xs)
| otherwise = Left (length xs, c)
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