From: Ralf Jung <post@ralfj.de>
Date: Wed, 25 Jul 2018 10:22:13 +0000 (+0200)
Subject: clarify extra-hidden-state-in-memory
X-Git-Url: https://git.ralfj.de/web.git/commitdiff_plain/b8756941fcd45799c686a244b3c36b42a03bc91a?ds=inline;hp=b01ea6eb37bd201791375ac95bad460ba8081168

clarify extra-hidden-state-in-memory
---

diff --git a/personal/_posts/2018-07-24-pointers-and-bytes.md b/personal/_posts/2018-07-24-pointers-and-bytes.md
index dfd6bd1..5d6b60d 100644
--- a/personal/_posts/2018-07-24-pointers-and-bytes.md
+++ b/personal/_posts/2018-07-24-pointers-and-bytes.md
@@ -162,7 +162,8 @@ We have to say what the value of `v` is, so we have to find some way to answer t
 (And this is an entirely separate issue from the problem with multiplication that came up in the last section. We just assume some abstract type `Pointer`.)
 
 We cannot represent a byte of a pointer as an element of `0..256`.
-Instead, we will remember both the pointer, and which byte of the pointer we got.
+Essentially, if we use a naive model of memory, the extra "hidden" part of a pointer (the one that makes it more than just an integer) would be lost whne a pointer is stored to memory and loaded again.
+We have to fix this, so we have to extend our notion of a "byte" to accomodate that extra state.
 So, a byte is now *either* an element of `0..256` ("raw bits"), *or* the n-th byte of some abstract pointer.
 If we were to implement our memory model in Rust, this might look as follows:
 {% highlight rust %}