Le 02/04/2011 21:30, Brendan Eich a écrit : > On Apr 2, 2011, at 12:16 PM, Brendan Eich wrote: > >> You must mean only in the cases where typeof a == typeof b, then a == b <=> >> a === b, and === is an e.r. But that does not mean == is an e.r. > Forgot typeof a == "object" above, to be precise. Indeed, I considered == to be an e.r. only in the contexts of objects. Sorry for the inaccuracy. Behavior when one side isn't an object would remain the same.
>> For mismatching types, == is not transitive, so not an e.r. Also, for NaNs >> it is not reflexive (neither is ===). > The desire for < (partial order) as well as a true e.r. is strong, though, so > thanks for raising this issue. > > The big question remains: Is some modular opt-in to better == (and <) for > objects worth the complexity? > What developers want, IMHO, is not Object.create and a specific object > o to pass as a member of an existing e.c., in which to create a new > object. That is tedious and painful, it requires _a priori_ arrangements. > > Rather, many developers wish == would work at least like so (same for > <): [1, 2] == [1, 2]. Hence the tuples and records ideas in > > http://brendaneich.com/2011/01/harmony-of-my-dreams/ > > whereby #[1, 2] == #[1, 2] and #[1, 2] < #[1, 3]. > > More could be done, for sure. If Array users, say on a module by > module basis, could "opt in" to better == and < semantics, that might > be worth the trouble of adding such opt-in new operators. Are there other use cases than this one (#[1,2]...)? If not, then tuples are the right solution and it leaves the room for objects to define their own ==. I'm surprised by the idea that == could be defined on a per-value comparison basis on objects (Array as you give it as an example). It doesn't make the relation last throughout the program lifetime (which is what I was trying to do and requires a priori arrangements). I would expect an equivalence relation to last throughout the program. Like === does. With the defintion I tried to give to ==, I admit that it does not open the door for a < to be defined on objects. David _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
