[northzen]

I think the best compromise would be to get the best of two words. By default perform bound checks, but have a compiler flag which skips it. Might broke many programs written with default behaviour in mind, but allow perform additional optimizations.

[postflopclarity]

this is exactly what julia does. boundschecks are default on, and there are compiler flags --- either locally, via the `@inbounds` macro, or globally with `--check-bounds=no`--- to disable them