Program logic bugs vs input/environmental errors

[eles via Digitalmars-d]

On Saturday, 18 October 2014 at 17:40:43 UTC, Walter Bright wrote:
> On 10/18/2014 8:21 AM, Jacob Carlborg wrote:
>> On 2014-10-18 07:09, Walter Bright wrote:
>>
>>> Which means they'll be program bugs, not environmental errors.
>>
>> Yes, but just because I made a mistake in using a function 
>> (hitting an assert)
>> doesn't mean I want to have undefined behavior.
>
>
> As I've said before, tripping an assert by definition means the 
> program has entered an unknown state. I don't believe it is 
> possible for any language to make guarantees beyond that point.

What about using the contracts of a fucntion to optimize? They 
are mainly asserts, after all.