On Feb 15, 2011, at 14:36 , Attila Lendvai wrote:

- The idea that COMPARE returns symbols also seems weird to me. Wouldn't it be better to return numbers (-1, 0, +1 or NIL)? Can't immediately tell why, though.

you need to return well-known identities that communicate the result.
-1,0,+1 are the easy way for well-known identities in C. in CL,
symbols provide a much nicer framework to deal with well-known
identities IMO.

That was the thinking.

- Shouldn't there also be a hash-code generic function that can be specialized alongside AEQUALIS? This also exists in Java and C#, and could make this immediately more useful (and would be much harder to add later as an afterthought). Many CL implementation add an :sxhash option to make-hash-table, where such a hash-code function could be used.

a big +1 for the above.

You should but:

As in Java (and FWIU in C#) there are no "easy" ways (for an appropriate definition of "easy") to enforce the protocol.
What would be the default? Something like

(defmethod hash-code ((x t)) (sxhash x))

If you think so, I can add it to the doc. Always with the caveat that there is no way to enforce the relationship between equality and hashing.

Marco

PS. Yeah. AEQUALIS is very Latin :) Any synonym? I will just vote against EGAL, which I really don't like :)

--
attila

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