Great article but a terrible topic for a "beginner-level" tutorial.
A small introduction to PCI compliance requirements would be great to stop beginners from thinking they can process credit card numbers as easy as this...
The intended takeaways here are checksums and the functional-style implemention - definitely not intended as an introduction to financial processing.
Sure, that's why I think it is a bad topic for a tutorial.
The programming style is cool, but it would be better if you implemented another algorithm, something that could be used in a real world app, or at least warn the readers they should never get credit card numbers in their app (unless they are building a bank..)
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