[AyanamiKaine]

I am actually excited for post and pre conditions. I think they are an underused feature in most languages.

[augustk]

Postconditions are in conflict with programmers' love of early returns.

[HelloNurse]

Formally, it doesn't appear to be so (tests can be added to each early return); in practice, encouraging the reorganization of messy early returns would be zero cost developer reeducation.