Head in the Cloud

The web is riddled with articles on this very topic, yet it bares repeating: never use float for money. I repeat: never never never never never use a floating point data type to represent monetary values or do financial math. Why? Single and Double precision floating point numbers are not accurate. Ironically, it's by design. They are optimized for performance where absolute accuracy is not a concern. Microsoft talks about it briefly here:  https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/floating-point-numeric-types [...]there's no double or float instance that exactly represents 0.1. Because of this difference in numeric types, unexpected rounding errors can occur in arithmetic calculations when you use double or float for decimal data. Baeldung has an excellent writeup on the science behind why floats behave the way they do:  https://www.baeldung.com/cs/floating-point-numbers-inaccuracy So what should we use for money and financial calculation...

Customer-First. Team-Focused. I like to take a customer-first approach to architecture and software design. A system architecture should always deliver value to the customer. Either directly--features, user experience--or indirectly by enabling teams to deliver value. If a team is going to be able to deliver value, the system needs to be easy to reason over, easy to maintain, easy and safe to extend, and easy to operate. Every architecture or design decision should answer: How does this deliver value to my customer? How does this deliver value to my team? Competing Styles. The Swinging Pendulum. It seems the big debate lately is monolith vs microservices. Academically, each at the opposite end of the spectrum: the massive, single deployable unit monolith on one end and the highly decomposed highly distributed microservices on the other. Each come with their pros and cons and serve teams better depending on team size, skill level, and goals. Notice I didn't include the customer in t...