On Friday, 13 November 2015 at 08:51:27 UTC, Ali Çehreli wrote:
I understood Walter's response to be so.
That's my interpretation of what Walter has said before too. So a
D compiler cannot prevent compilation of a statically detected
wrapping (overflow). As a result D-integers are circular
enumerations.
On the other hand, in order to define the wrapping behavior at
all, one must speak of overflow first.
For educational purposes, probably :-)
Wrapping is the solution for the condition of overflow, which D
must have to begin with, no? :)
For definition, not really. Signed integers are often defined as
three functions (other definitions are possible):
Zero: 0
Successor of X: S
Predecessor of X: P
For a 2 bit signed modular arithmetics you would get the complete
normalized set:
PP0, P0, 0, S0
with the defined rewrites
SPX = X
PSX = X
PPP0 = S0
SS0 = PP0
(implies PPPPX = X and SSSSX = X)
then you define the operators on the set (+,- etc) using
relations such as PSX = X etc.
