Structural pattern matching support

[brunns]

I'm thinking about whether it would be useful to add explicit support for Python 3.10's new structural pattern matching feature, and if so, what it might look like.

[offbyone]

Good question. Certainly we can't use it in the core until 3.9 falls off the support matrix, but I'm interested in what you have in mind otherwise.

[brunns]

Yeah - I was wondering if it would be useful and possible to use a matcher as a pattern, and if so, whether there's anything backward compatible we can do to make this more convenient.

This kind of thing I was thinking of is:

from hamcrest.library.text.stringendswith import ends_with

obj = 'sausages'

match obj:
    case ends_with('abc'):
        print("a")
    case ends_with('ges'):
        print("b")
    case _:
        print('no match')

Can't seem to make that work, though - I'm not sure user defined patterns are a thing.

[brunns]

They aren't, at least not yet.