[Python-ideas] Backward-incompatible changes for Python 4

[Greg Ewing]

Paul Moore wrote:
> now that Python has type
> inference, it should be possible for users to just type {} and have
> the interpreter work out which was intended from context.

Or have {} return an ambiguous object that turns into a dict or
set depending on what is done to it.

We could call it a quict (quantum dict).

To support this, we would also have to add a third possible
value for type bool:

 >>> x = {}
 >>> isinstance(x, dict)
Maybe
 >>> isinstance(x, set)
Maybe
 >>> x['foo'] = 42
 >>> isinstance(x, dict)
True
 >>> isinstance(x, set)
False

-- 
Greg