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| -rw-r--r-- | doc/protocol/comment_3_e2d91431651d3ffe9072bd110b2fdc1d._comment | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/doc/protocol/comment_3_e2d91431651d3ffe9072bd110b2fdc1d._comment b/doc/protocol/comment_3_e2d91431651d3ffe9072bd110b2fdc1d._comment new file mode 100644 index 0000000..1318d16 --- /dev/null +++ b/doc/protocol/comment_3_e2d91431651d3ffe9072bd110b2fdc1d._comment @@ -0,0 +1,19 @@ +[[!comment format=mdwn + username="https://www.joachim-breitner.de/" + nickname="nomeata" + avatar="http://cdn.libravatar.org/avatar/a2112893817513537c6a2c228c04c138a2f68bba57121ab7f267de58fc5171d7" + subject="comment 3" + date="2017-05-07T03:19:14Z" + 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) +``` +"""]] |