[lilyball]

It is admittedly very weird that Go supports nil slices/maps instead of just having the nil value be an empty slice/map that points to constant storage. But as long as Go has a semantic difference internally, representing that as null externally makes sense. Though I suppose as long as the conversion from null to empty array/object is opt-in it's fine.

For context, we recently had a bug where backend forgot to initialize their map, so they were sending us a null where we expected an object, and it would have gone undetected for much longer if the JSON didn't contain a literal null there.

[yencabulator]

The nil value for a slice is an empty slice that points to constant storage: Data=0, Len=0, Cap=0. That's just not the same as Data=somethingelse, ... which you get if you allocate something.

(And all Go zero values are exactly what you get with the relevant RAM filled with the zero byte.)

[lilyball]

If the nil value for a slice is the empty slice, then why do the following two variable definitions differ in behavior?

  var x []int;
  y := []int{};

Both produce a slice of capacity zero, except `x` serializes to null and `y` serializes to an empty array.