decimal VS apd

Try it in JS with console.log(4.225 * 100);, you'll see the same unexpected result. Depending on your needs, it's actually fine to just be off by some amount. If it does really matter, then use an arbitrary precision library like https://github.com/shopspring/decimal to get the results you need.

Most programming languages ( JavaScript, PHP, Go, Python, Java, C# ) have built-in support or 3rd-party libraries for handling this data type, even though the internal implementations can differ:

while working with money, dont use floats, use something like https://github.com/shopspring/decimal (go std lib doesnt have its own decimals yet)

Integers, or something like this: https://github.com/shopspring/decimal

I make heavy use of caching, and was caching both in-memory and in Redis using JSON to convert the data in to a string. The struct itself isn't super complicated, one level nested, and some fields use the shopspring/decimal library.

I actually use this to represent monetary values btw :)

Check out https://github.com/shopspring/decimal for doing money related calculations.

We personally use https://github.com/shopspring/decimal and it works well.

decimal, one of the first Go library that created to work with decimal and monetary value.

https://github.com/shopspring/decimal also.

https://github.com/cockroachdb/apd is currently the best implementation in the ecosystem (performance, correctness). Have you already evaluated it?

FWIW I think cockroachdb/apd is the best third party option. While building bojanz/currency I've evaluated and benchmarked the others and found them either less maintained, slower, or both.

I have a package for handling currency amounts and calculations that is based on cockroachdb/apd, in my opinion the best arbitrary-precision decimal implementation in Go right now. So, I can offer a bit of insight.

The best decimal package is still cockroachdb/apd. I wrap it in bojanz/currency for money handling.

https://github.com/cockroachdb/apd remains the best decimal library for Go (ericlagergren/decimal is faster but unmaintained).

Note: In benchmarks ericlagergren/decimal was noticeably faster than cockroachdb/apd, but it has known bugs when used with go mod, so I decided to wait and go with cockroachdb/apd for now. The Amount struct wraps the decimal implementation completely, making it easy to do the swap later without breaking BC.