On 5 Sep 2020 Ram Rachum ram@rachum.com wrote:

Hi everyone,

Sorry if this was proposed already. I looked here https://www.python.org/dev/peps/pep-0622/#alternatives-for-constant-value-pa..., search for "idea to make lookup semantics the default". I saw that a few symbols like $ and ? were proposed, and I thought that maybe the annotation syntax -> could indicate a capture expression, like so:

case x: match Point(-> a, -> b): ... match -> whatever: do_something(whatever)

I like the arrow because it's easy to imagine the value "entering" the variable. What do you think?

Thanks, Ram.

Nice! :)

Combined with keywords that could become: Point(x -> a, y -> b)

or, mixed with providing values: Point(x -> a, y=42)

And we wouldn’t need match -> whatever: because we already have x, and if x is an expression I’d prefer case x as whatever: