A hypothetical solution is to carry around the interval of immutable values between lines and use the contracts to shape such intervals, as asked here:https://d.puremagic.com/issues/show_bug.cgi?id=10594
Please vote the issue, now you have 20 votes :-)Pre-state (old), the shaping of in/immutable value ranges with contracts, and few more things make D contract programming more useful.
Bye, bearophile
