[the_why_of_y]

Interestingly, the first Ada standard in 1983 defined signed integer overflow to raise a CONSTRAINT_ERROR exception.

But apparently it lacked unsigned integers with modular arithmetic?

http://archive.adaic.com/standards/83lrm/html/lrm-11-01.html... http://archive.adaic.com/standards/83lrm/html/lrm-03-05.html

The 2012 version is a bit more readable, and has unsigned integers:

For a signed integer type, the exception Constraint_Error is raised by the execution of an operation that cannot deliver the correct result because it is outside the base range of the type. For any integer type, Constraint_Error is raised by the operators "/", "rem", and "mod" if the right operand is zero.

For a modular type, if the result of the execution of a predefined operator (see 4.5) is outside the base range of the type, the result is reduced modulo the modulus of the type to a value that is within the base range of the type.

http://www.ada-auth.org/standards/rm12_w_tc1/html/RM-3-5-4.h...