Greetings all,
We can do one type annotations like list[int] and dict[str, int], my question:
why don’t we have a similar thing in matching patterns? Especially if you want
to enforce a type on a sequence or a dictionary with unknown length.
For example,
ls = [3.14, ‘hello’, 1, 2, 3, 4, ...]
d = {‘name’: 1, ‘age’: 25, ...}
match ls:
case [float(), str(), *rest] if all(isinstance(elem, int) for elem in rest):
... (do something with rest)
We do the same thing with the following:
case [float(), str(), *int() as rest]: (do something with rest)
match d:
case **rest if all(isinstance(k, str) and isinstance(v, int) for k, v in
rest.items()): (do something with rest)
We do the same thing with the following:
case **{str() as keys: int() as values} as rest: (do something with rest or
with keys (=rest.keys()) and values (=rest.values()) directly)
{str() as k: int() as v} matches a dictionary that has at least one structure
of str(): int() but what would the values of k and v be in this case? Is It the
first match since python dictionaries are now ordered? Or this is not permitted
in dictionary matching? I saw examples like {‘string literal’: int() as v} on
the web.
What do you think of this idea?
Abdulla
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