Tutorial files

luhn.lhs

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+This is an implementation of the Luhn Algorithm. It's used to validate credit card numbers.
+
+> lastDigit :: Integer -> Integer
+> lastDigit n = mod n 10
+
+> dropLastDigit :: Integer -> Integer
+> dropLastDigit n = div n 10
+
+> toRevDigits :: Integer -> [Integer]
+> toRevDigits n
+>   | n < 1     = []
+>   | otherwise = lastDigit(n) : toRevDigits(dropLastDigit(n))
+

test.lhs

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+
+Compute the factorial of a given integer number n.
+
+> fac :: Integer -> Integer
+> fac 0 = 1
+> fac n = n * fac(n-1)
+
+Compute the sum of of all integer numbers from 1 to n.
+
+> sumTo :: Integer -> Integer
+> sumTo 0 = 0
+> sumTo n = n + sumTo(n-1)
+