[hop] Client-side ‘equal?’ vs. objects

[Ludovic Courtès]

On the client side, ‘equal?’ does not compare objects structurally as is
the case on the server side:

--8<---------------cut here---------------start------------->8---
function sc_isEqual(o1, o2) {
    return ((o1 === o2) ||
            (sc_isPair(o1) && sc_isPair(o2)
             && sc_isPairEqual(o1, o2, sc_isEqual)) ||
            (sc_isVector(o1) && sc_isVector(o2)
             && sc_isVectorEqual(o1, o2, sc_isEqual)));
}
--8<---------------cut here---------------end--------------->8---

The problem is that:

--8<---------------cut here---------------start------------->8---
new Object({a: 3}) === new Object({a: 3})
⇒ false
--8<---------------cut here---------------end--------------->8---

Thus, two instances that are ‘equal?’ on the server side are not
‘equal?’ on the client side.

I was considering changing ‘scm_isEqual’ along these lines:


diff -r d5c1b8a88937 scheme2js/runtime/immutable.js
--- a/scheme2js/runtime/immutable.js	Tue Sep 10 10:59:36 2013 +0200
+++ b/scheme2js/runtime/immutable.js	Thu Sep 12 17:54:31 2013 +0200
@@ -84,7 +84,8 @@
 	    (sc_isPair(o1) && sc_isPair(o2)
 	     && sc_isPairEqual(o1, o2, sc_isEqual)) ||
 	    (sc_isVector(o1) && sc_isVector(o2)
-	     && sc_isVectorEqual(o1, o2, sc_isEqual)));
+	     && sc_isVectorEqual(o1, o2, sc_isEqual)) ||
+	    (hop_obj_to_string(o1) === hop_obj_to_string(o2)));
 }
 
 /*** META ((export number->symbol integer->symbol) (arity -2)) */

but this doesn’t work due to the fact that ‘hop_obj_to_string’ is
non-deterministic.

WDYT?

Thanks,
Ludo’.