Limiting effects*
Rye as a language is very flexible, it tries to be very flexible in letting you define the procedure. But it tries to be much more strict in terms of it’s environment, especialy modifications of it.
Visible in-place modifications
Most functions in Rye return values, and don’t change them in place. In fact I would say we usually use just these functions and you can do anything with just those functions.
But sometimes you want to specifically change some state in-place, so that must be possible too. To make it possible, but visible all such function names must end with “!” or must include wordage “mod-” “set-”.
-convention is still somewhat being tested in practice-