In practice it would be encoded in comments, automated tests and docs, with varying levels of success.

It’s actually similar to tests in a way: they provide additional confidence in the code, but at the same time ossify it and make some changes potentially more difficult. Interestingly, they also make some changes easier, as long as not too many types/tests have to be adapted.

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estebank 5 days ago | parent | next [-]

This reads to me like an argument for better refactoring tools, not necessarily for looser type systems. Those tools could range from mass editing tools, IDEs changing signatures in definitions when changing the callers and vice versa, to compiler modes where the language rules are relaxed.

	▲	jbritton 5 days ago \| parent [-]
		I was thinking about C++ and if you change your mind about whether some member function or parameter should be const, it can be quite the pain to manually refactor. And good refactoring tools can make this go away. Maybe they already have, I haven’t programmed C++ for several years.

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gf000 5 days ago | parent | prev [-]

Constraints Liberate, Liberties Constrain. (I also recommend watching the presentation with the same title)