Vogen

There are libraries for that, such as Vogen https://github.com/SteveDunn/Vogen The name means "Value Object Generator" as it uses Source generation to generate the "Value object" types. That readme has links to similar libraries and further reading.

Agreed! Expanded type guards can replace a huge amount of unit tests in a way that is more concise and provides a better promise to more of the code. It's about orientation. Orienting around the data makes so much more sense. Why test every function's email address param when you can instead guard via an email address type? Typescript is the most popular language to try and their type system is a lot of fun. However, the compiler messages remind me of working with Boost libs in C++. It's also unfortunate that typescript actually provides no guarantee about runtime so I never have complete confidence like I do with real static typed languages. You can also get to a point in typescript where you go down a type system rabbit hole and find yourself a code philosopher. It's been a personal black hole for time wasting on a project for me. Libs

I usually run into issues at the boundaries in the system. Usually moving from primitives into complex types does not account for serialization and deserialization between db and the client. This can be very annoying to work with in something like C#. Usually it ends up resulting in alot more types and a lot more mapping between types. However this has its own benefits, but is very boilerplate-y and is sluggish to work with when your domain changes. Luckily, for C#, https://github.com/SteveDunn/Vogen now exists thanks to source code generators which soothes some of the issues.