Rick Johnson wrote:
> IMO "Set Types" should only exists as a concequence of "freezing" an
> array,
Sets are not frozen lists.
> and should have NO literal syntax avaiable.
Unfortunately, Python has a minor design flaw. One of the most common
use-cases for sets is for membership testing of literal sets:
def example(arg):
if arg in {'spam', 'ham', 'eggs', 'cheese'}:
...
Unfortunately, set literals create *mutable* sets, not frozensets. That
means that the compiler wastes time and memory creating am over-allocated
mutable set object. If set literals created immutable frozensets, there
would be some nice opportunities for the compiler to optimize this
use-case.
So, in Python 4000, my vote is for set literals { } to create frozensets,
and if you want a mutable set, you have to use the set() type directly.
--
Steven
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