2021-07-12 07:51:10 <cbridge     > <proteusguy> you can always use the double xor to swap between two items without having an intermediate variable.
2021-07-12 07:56:27 <eris[m]1    > double xor?
2021-07-12 12:06:53 <crc         > eris[m]1: I'd assume it's the trick that lets you do something like `x = x ^ y`, `y = x ^ y`
2021-07-12 12:07:33 <crc         > `x = x ^ y`
2021-07-12 12:10:01 <eris[m]1    > ahh
2021-07-12 12:10:15 <eris[m]1    > i wonder what that would look like on the stack
2021-07-12 13:05:08 <tangentstorm> kinda doesn't make sense on a stack, unless it's how you implement swap internally.
2021-07-12 13:08:39 <imode       > what doesn't.
2021-07-12 13:08:59 <tangentstorm> the double xor trick for swapping two values without an intermediate.
2021-07-12 13:10:46 <imode       > ah. yeah I mean.. the effect is the same.
2021-07-12 13:21:52 <siraben     > the limitation is of course the items cannot be the same because x ^ x = 0
2021-07-12 13:22:00 <siraben     > for x : bool
2021-07-12 13:26:41 <tangentstorm> they can be the same.  x=1, y=1 ... x=x^y -> x=0 ... y=x^y -> y=1 .. x=x^y -> x=1... final state:  x=1, y=1.
2021-07-12 13:27:55 <siraben     > oh I mean if x and y are the same storage location
2021-07-12 13:28:01 <siraben     > but yeah as long as they're separate it's fine
2021-07-12 13:28:09 <tangentstorm> ohh
2021-07-12 13:32:27 <siraben     > remexre: ^ would be a nice exercise to formally verify
2021-07-12 13:33:07 <siraben     > I would opt for a Hoare logic assertion, {{ X ::= a ; Y ::= b }} XOR_SWAP {{ X ::= b ; Y ::= a }}
2021-07-12 18:55:48 <dave0       > maw
2021-07-12 23:06:45 <dave0       > re maw