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authorhttps://www.joachim-breitner.de/ <nomeata@web>2017-05-07 03:20:39 +0000
committeradmin <admin@branchable.com>2017-05-07 03:20:39 +0000
commit0d178f087b6a0a5c761df7765d15544dcff948a1 (patch)
tree53b0425487a9574954d1355180754e09f1ae1a4d
parent09d8a31d108c37bcf92096c03659f4ad97062945 (diff)
downloaddebug-me-0d178f087b6a0a5c761df7765d15544dcff948a1.tar.gz
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+[[!comment format=mdwn
+ username="https://www.joachim-breitner.de/"
+ nickname="nomeata"
+ avatar="http://cdn.libravatar.org/avatar/a2112893817513537c6a2c228c04c138a2f68bba57121ab7f267de58fc5171d7"
+ subject="comment 3"
+ date="2017-05-07T03:20:38Z"
+ content="""
+Still not good, I think, as the instance `Hashable Hash` has `hash = id`, so
+
+ hash Nothing
+ = hash ()
+ = id (hash ())
+ = hash (Just (hash ())
+
+ and we have a collision at type `Maybe Hash`.
+
+What would work is to do the same that `Hashable []` does, i.e. has the hash again:
+
+ hash (Just v) = hash (val (hashValue v))
+ hash Nothing = hash (mempty :: B.ByteString)
+
+"""]]