3 ms·
That's correct, it's a run-time check. According to https://en.wikibooks.org/wiki/Ada_Programming/Types/range https://en.wikibooks.org/wiki/Ada_Programming/Ty
by DonaldFisk 9y ago
That's correct, it's a run-time check. According to https://en.wikibooks.org/wiki/Ada_Programming/Types/range https://en.wikibooks.org/wiki/Ada_Programming/Types/range
A range is a signed integer value which ranges from a
First to a last Last. It is defined as
range First .. Last
When a value is assigned to an object with such a range
constraint, the value is checked for validity and
Constraint_Error exception is raised when the value is
not within First to Last.
- HumanDrivenDev 9y agoRight. I said dependent types would allow you to statically declare integer ranges, as is my understanding. It's interesting to me how Ada takes the approach of blending types and run time contracts. In most languages it would be two different things - a function that takes int, then a contract or assert that handles the value.
- DonaldFisk 9y agoThey allow you to statically declare integer ranges (as well as other things), even if their bounds are unknown until run-time, and without requiring a run-time type check.
- mjn 9y agoSome Lisp implementations (like SBCL) also do that blending, although they can statically catch some integer range violations too. For example if you declare a variable to be an (integer 50 100) and try to assign a literal 30 to it, you'll get a compile-time warning in SBCL: ; Constant 30 conflicts with its asserted type (INTEGER 50 100). But in many other cases it'll generate a runtime check instead, because the static type checking is basically best-effort.