Validate a card number. The algorithm follows these steps:

• Double the value of every second digit beginning with the rightmost.
• Add the digits of the doubled values and the undoubled digits from the original number.
• Calculate the modulus of the sum divided by 10.

If the result equals 0, then the number is valid.

This project uses stack. You can read a Quick Start Guide for basic information.

git clone [email protected]:azdanov/haskell-card-validator.git
cd haskell-card-validator
stack setup
stack build

Stack provides a mechanism to run a built executable:

stack exec card-exe

Enter a Card Number:
4556945538735694
Number 4556945538735694 is invalid.


stack exec card-exe

Enter a Card Number:
5256283618614517
Number 5256283618614517 is valid.

Hspec is used for testing. To run the testing suite execute:

stack test

MIT