One annoying with an MPTC approach is that suddenly defaulting stops working.

This can result in a requiring of a lot more signatures from users or little helpers everywhere like the 'sip' below.

-Edward

On Thu, Mar 21, 2013 at 10:36 AM, Bas van Dijk <v.dijk.bas@gmail.com> wrote:
On 21 March 2013 06:54, wren ng thornton <wren@freegeek.org> wrote:
> One concern with the above approach: is "siphash" a sufficiently generic
> name, or is it just one hashing method that happens to deflect this DoS
> issue? I haven't read the paper, so...

One could of course generalize the above method using something like:

-- A type hashed as h
newtype Hashed h a = Hashed a

instance (HashableAs h a) => Hashable (Hashed h a) where
  hashWithSalt = hashWithSaltAs

class HashableAs h a where
  hashWithSaltAs :: Int -> Hashed h a -> Int

data Sip

sip :: a -> Hashed Sip a
sip = Hashed

instance HashableAs Sip Text where
  hashWithSaltAs salt (Hashed x) = sipHashWithSalt salt x

instance HashableAs Sip ByteString where
  ...

Regards,

Bas

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