Evan Miller evanmiller
evanmiller
/ gist:5834171
Last active
December 18, 2015 19:39
— forked from pragdave/gist:5833805
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| defmodule CheckDigit do | |
| import Enum | |
| @doc """ | |
| Determine if a sequence of digits is valid, assuming the last digit is | |
| a Luhn checksum. (http://en.wikipedia.org/wiki/Luhn_algorithm) | |
| """ | |
| def valid?(numbers) when is_list(numbers) do |