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>If () = () is false, then it's intuitive (to me) that deep-equal((),
()) is also false. The one liner saying that it should be true just
seems like it could easily say false.
A = B means (some $a in A, $b in B satisfies $a eq $b). Therefore () = () is false. deep-equal(A, B) means (count(A) eq count(B) and every $i in 1 to count(A) satisfies A[$i] eq B[$i]). Therefore deep-equal((), ()) is true. So it's perfectly consistent. It's also absolutely necessary. Given that for two elements to be equal, their sequences of children have to be deep-equal, it would be very odd if two elements were not deep-equal simply because neither has any children. Indeed, it would be very odd if an element were not deep-equal to itself. (Note, the above expansions are approximate. They don't quite handle NaN, but that's another can of worms.) Michael Kay Saxonica
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