week9 tweak

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

diff --git a/week9.mdwn b/week9.mdwn
index 4e334a0..ba99a79 100644 (file)
--- a/week9.mdwn
+++ b/week9.mdwn
@@ -370,7 +370,7 @@ Here's how to implement these. We'll suppose that our assignment function is lis
                        in eval expr2 g s''
 
 
-##How to implicit mutation with a State monad##
+##How to implement mutation with a State monad##
 
 It's possible to do all of this monadically, and so using a language's existing resources, instead of adding new syntactic forms and new interpretation rules to the semantics. The patterns we use to do this in fact closely mirror the machinery described above.