Money is one of those areas where small omissions can generate technical debt faster than almost any other slice of an application domain. Not because “finance is hard,” but because average code likes to pretend it’s simple. Bankster is an attempt to do this thing properly.

Last night I received an e-mail in which one of my visitors asked me a few questions after reading the post about parsing phone numbers in Clojure. The question was seemingly simple and concerned a technical detail of software construction, but in reality the reader touched on a very important subject that I had been pondering years ago, and I decided to summarise it here.