MyPy does not like tuples assigned to variables and then used as type arguments

Question

I have a list structure as a flattened input to a API

(point_x, point_y, thing_a, thing_b, thing_c)

This real structure is a very long list of a many flattened objects. This example is a much simplified case.

I would like to make the types that create it clear in python

from typing import Tuple

point = (int, int)
thing = (int, float, str)
TypeA = Tuple[point + thing]

This is a valid python type:

typing.Tuple[int, int, int, float, str]

However, MyPy does not like it.

"Invalid type alias: expression is not a valid typeMypyvalid-type"

The real structure I have is very complex and it's helpful for devs to see how the structure is created.

How can I do this properly without MyPy causing errors

---

Just as an addendum, the following is not a valid solution

from typing import Tuple
Tuple[
    int,     # point_x
    int,     # point_y
    int,     # thing_a
    float,   # thing_b
    str      # thing_c
]

Answer 1

You need to define "type-level tuples", using tuple[...], not (...).

point = tuple[int, int]
thing = tuple[int, float, str]

You can unpack them to define TypeA:

TypeA = tuple[*point, *thing]

which can then be used as a type hint:

x: TypeA = (1, 2, 3, 4.5, "foo")  # OK
y: TypeA = ("bar", 2, 3, 4.5, "foo")  # Error