Estimate Dutch income tax the UNIX way.
Disclaimer: This project was a just a semi-useful, quick hack to learn more Haskell. @ArdaXi states that this estimator is very basic and could be completely wrong. I believe him, he's good with numbers. Do not use this for actually calculating your tax.
$ npm -g install dutch-income-tax
$ dutch-income-tax
1000
-100
1200
^D
122.85000000000001
Pipe to it from your invoice management system or whatever.