ruff/crates/ty_python_semantic/resources/mdtest/binary/in.md

Static binary operations using in

Basic functionality

This demonstrates type inference support for <str-literal> in <tuple>:

from ty_extensions import static_assert

static_assert("foo" in ("quux", "foo", "baz"))
static_assert("foo" not in ("quux", "bar", "baz"))

With variables

from ty_extensions import static_assert

x = ("quux", "foo", "baz")
static_assert("foo" in x)

x = ("quux", "bar", "baz")
static_assert("foo" not in x)

Statically unknown results in a bool

def _(a: str, b: str):
    reveal_type("foo" in (a, b))  # revealed: bool

Values being unknown doesn't mean the result is unknown

For example, when the types are completely disjoint:

from ty_extensions import static_assert

def _(a: int, b: int):
    static_assert("foo" not in (a, b))

Failure cases

# We don't support byte strings.
reveal_type(b"foo" not in (b"quux", b"foo", b"baz"))  # revealed: bool