It would be awfully nice if there were a way to optionally get bounds-checked versions of array primitives. The idea would be that if GHC is compiled with a bounds-checking option, then the code generator would use primops that verify indices are in bounds. Based on [a question by Henning Thielemann](https://mail.haskell.org/pipermail/haskell-cafe/2018-April/128992.html), I suspect such a feature would get some use. The biggest challenge: `SomeException`, `Typeable`, `Show`, `String`, `CallStack`, etc., all live in an entirely different universe than the primops, so it's not exactly obvious how to get started. I don't know if it would be possible to inject references to such things into a lower level. Sounds hard, but maybe it's possible. An alternative, probably much simpler, approach would be to crash hard with an error message instead of trying to throw a proper exception. Ideally, the error message would include the name of the primop and (for modules compiled with profiling) some call stack info. <details><summary>Trac metadata</summary> | Trac field | Value | | ---------------------- | ------------------ | | Version | 8.2.2 | | Type | FeatureRequest | | TypeOfFailure | OtherFailure | | Priority | normal | | Resolution | Unresolved | | Component | Compiler (CodeGen) | | Test case | | | Differential revisions | | | BlockedBy | | | Related | | | Blocking | | | CC | | | Operating system | | | Architecture | | </details> <!-- {"blocked_by":[],"summary":"Optionally bounds-check primops","status":"New","operating_system":"","component":"Compiler (CodeGen)","related":[],"milestone":"8.6.1","resolution":"Unresolved","owner":{"tag":"Unowned"},"version":"8.2.2","keywords":[],"differentials":[],"test_case":"","architecture":"","cc":[""],"type":"FeatureRequest","description":"It would be awfully nice if there were a way to optionally get bounds-checked versions of array primitives. The idea would be that if GHC is compiled with a bounds-checking option, then the code generator would use primops that verify indices are in bounds. Based on [https://mail.haskell.org/pipermail/haskell-cafe/2018-April/128992.html a question by Henning Thielemann], I suspect such a feature would get some use.\r\n\r\nThe biggest challenge: `SomeException`, `Typeable`, `Show`, `String`, `CallStack`, etc., all live in an entirely different universe than the primops, so it's not exactly obvious how to get started. I don't know if it would be possible to inject references to such things into a lower level. Sounds hard, but maybe it's possible.\r\n\r\nAn alternative, probably much simpler, approach would be to crash hard with an error message instead of trying to throw a proper exception. Ideally, the error message would include the name of the primop and (for modules compiled with profiling) some call stack info.","type_of_failure":"OtherFailure","blocking":[]} -->