On 2006-03-26, Daniel McAllansmith
I was thinking about several things in this thread, torsors, overflow semantics, bounds checking... I wonder if there would be any merit in being able to define constrained subsets of integers and the semantics when/if they overflow.
For example, take UNIX nice levels -20 to 19. You could have data ConstrainedInteger = CI {distToMax :: Natural, distToMin :: Natural} this would ensure only the 40 integers can be represented. Then you could have _something_ that defined what happened on overflow, whether it wraps, reflects, errors, truncates or whatever.
When it comes to compile, or source preprocessing, time these numbers could be realigned to a primitive Int or Word representation of suitable size and have the appropriate overflow code written in. And, in the case of error or wrap overflow semantics on a set of the right size, the overflow checks could be disabled, like other assertions, at runtime.
Now that is an interesting idea. -- Aaron Denney -><-