Ada 2012 supports preconditions, postconditions, type predicates, and type invariants directly in the language: https://learn.adacore.com/courses/intro-to-ada/

Ada 2012 supports preconditions, postconditions, type predicates, and type invariants directly in the language: https://learn.adacore.com/courses/intro-to-ada/chapters/contracts.html https://learn.adacore.com/courses/intro-to-ada/chapters/cont... It is wonderful for tracing errors and detecting problems, but can be a royal pain if you are refactoring substantial parts of the code / design.