It is so nice to come here and want to say something, and someone already said it.

For those who haven't read "Parse, Don't Validate": https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-va...

I'm not sure exactly what languages people think of when they consider asserting, but I presume it's Java, C# or C/C++. In Java asserts are disabled by default, so they're thought of as a debug/development utility.

In another thinkpiece, "It takes two to Contract", it is demonstrated how types and assertions work together in TigerBeetle: https://tigerbeetle.com/blog/2023-12-27-it-takes-two-to-cont...

I think people might be worried of asserting in production because "what if you hit an edge case in production that you haven't accounted for, and the system crashes?" And I either think "You just don't test enough", or "Parse, Don't Validate (rather than assert), report a problem and continue."

> Users of the value who care about the invariant being true can then specify in their types that they want

Now that C# has value types and Java has record classes, this kind of data modelling has become available in mainstream systems languages. I'm not a C++ shark, but I think the closest equivalent is C++20 aggregate structs.