Class PatternType

mypy/checkpattern.py:82–85

# the PatternTypes of the sub-patterns first.
# Using the data in the PatternType the match subject and captured names can be narrowed/inferred.
class PatternType(NamedTuple):
    type: Type  # The type the match subject can be narrowed to
    rest_type: Type  # The remaining type if the pattern didn't match
    captures: dict[Expression, Type]  # The variables captured by the pattern


class PatternChecker(PatternVisitor[PatternType]):