If I’m going to write code by hand, the requirement for a beautiful pleasant language is bigger than ever.

The main problem is code organization and syntax. Tacking stuff like this onto fuction declarations is too basic.

Ideally, I think we need better constructs, e.g. dettached constraints like to the function declaration. You can define constraints separately, in the same namespace or w/e, add notes, comments, etc. and the function declaration can be used with intellisense to jump to the constraint. You could even tag the defintions.

In modern AI-based workflows, the agent can pull up an explanation on the function, and point directly to the constraints, with strong confidence esp. if it's got explicit metadata.

https://en.wikipedia.org/wiki/Design_by_contract

https://www.eiffel.com/values/design-by-contract/introductio...

If I put them in the header, I have to include half the world because I can't forward declare `Foo foo` argument if I want to check `foo.size() > 3` or similar in a pre/post-condition. This is a non-starter, keeping headers lean is the only way to not end up with 1 hour compiles.

If I put them in the cpp, they lose their only advantage over asserts - that they also double as documentation in the headers.

Did we add 50 pages to the standard for a slightly fancier assert? I feel like this could've been one builtin and a footnote:

contract_assert(expr) - if expr evaluates to false, the behavior of the program is undefined. Implementations are encouraged to emit a runtime check for this in debug builds, or a compiler error in cases where they can statically determine, that the assert will fail.