On 2022-01-21 00:18, Cameron Simpson wrote:
Well, I've just waded through this discussion.
This all feels to me like a special case of "wanting a constant for bytecode". What is we had a "freeze" operator, eg:
|foo|
which would produce a frozen version of foo. I'm liking the vertical bars myself, I think because it feels vaguely slightly analogous to "absolute value". So (assuming we can squeeze it into the expression syntax):
|{1,2,3}|
always makes a direct frozen set on the same basis that:
x in {1,2,3}
directly makes a frozenset by expression inspection. Then
Paired with a __freeze__ dunder method, this applies to any type, not just sets. (Where appropriate of course.)
So:
|{1,2,3}| frozen set |[1,2,3]| tuple! |any-iterable| tuple! |{1:2, 3:4}| frozen dict
Ths saves us (a) inventing a special syntax for frozen sets and (b) gateways to freezing many things, starting with the obvious above, via the __freeze__ dunder method.
This feels more general and less bikeshedable.
My main question is: is the syntax unambiguous?
I don't know whether it's unambiguous, but it could be confusing. For example, what does this mean: | a | b | ? It's: | (a | b) | I think. The problem is that '|' could be an opening '|', a closing '|', or an infix '|'. You don't get this problem with differing open and closing pairs such as '(' and ')'.