week9 tweak

Signed-off-by: Jim Pryor <profjim@jimpryor.net>

diff --git a/week9.mdwn b/week9.mdwn
index b2fbb3a..7028e89 100644 (file)
--- a/week9.mdwn
+++ b/week9.mdwn
@@ -332,7 +332,7 @@ Let's consider how to interpet our new syntactic forms `newref`, `deref`, and `s
                                in (Index new_index, s'')
                        ... 
 
                                in (Index new_index, s'')
                        ... 
 

-2.     When `expr` evaluates to a `store_index`, then `deref expr` should evaluate to whatever value is at that index in the current store. (If `expr` evaluates to a value of another type, `deref expr` is undefined.) In this operation, we don't change the store at all; we're just reading from it. So we'll return the same store back unchanged.
+2.     When `expr` evaluates to a `store_index`, then `deref expr` should evaluate to whatever value is at that index in the current store. (If `expr` evaluates to a value of another type, `deref expr` is undefined.) In this operation, we don't change the store at all; we're just reading from it. So we'll return the same store back unchanged (assuming it wasn't changed during the evaluation of `expr`).

 
                let rec eval expression g s =
                        match expression with
 
                let rec eval expression g s =
                        match expression with