fix from nomeata's review

He pointed out that Just () and Nothing would hash the same.
Luckily Maybe Hash is the only Maybe type that needs to be hashed,
so specialize the instance.

2 files changed, 11 insertions, 1 deletions

diff --git a/Hash.hs b/Hash.hs
index 8a33803..a76e0b4 100644
--- a/Hash.hs
+++ b/Hash.hs
@@ -84,7 +84,7 @@ instance Hashable [Hash] where
 	hash = hash . B.concat . map (val . hashValue)
 
 -- | Hash empty string for Nothing
-instance Hashable v => Hashable (Maybe v) where
+instance Hashable (Maybe Hash) where
 	hash Nothing = hash ()
 	hash (Just v) = hash v
 
diff --git a/doc/protocol/comment_2_4a25b8ee6e438a031e875078ffb1d125._comment b/doc/protocol/comment_2_4a25b8ee6e438a031e875078ffb1d125._comment
new file mode 100644
index 0000000..935570d
--- /dev/null
+++ b/doc/protocol/comment_2_4a25b8ee6e438a031e875078ffb1d125._comment
@@ -0,0 +1,10 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 2"""
+ date="2017-05-06T01:34:39Z"
+ content="""
+Thanks for that review. That would indeed be bad. To avoid that
+potential problem, I've specialized the instance to 
+`Hashable (Maybe Hash)`, which is the only Maybe value that currently
+needs to be hashed.
+"""]]