How to find type of a Python variable when hovering the mouse cursor over a variable in Visual Studio Code?

Question

I want to find out its type when hovering over a variable with the mouse, but this does not work. Does anyone know how to do this? For example, when hovering over x, it writes some kind of Literal, although I directly declared the type of the variable as int.

Answer 1

In the tooltip, Literal refers to typing.Literal, which is a special form used to define a type that is the set of all given literal values.

Easy to see that Literal[1] is a subtype of int, Literal['foo'] is a subtype of str and so on.

In this case, the type checker (Pyright) is able to infer a more specific type for x, so it went ahead and did just that. This is a feature, not a bug. Depending on the flow, this type might change:

_(playground)

x = 1235
reveal_type(x)      # Literal[1235]

for _ in range(0):
    x += 2
    reveal_type(x)  # int

reveal_type(x)      # int

It should also be noted that this might or might not be the case with other type checkers; that is, this is implementation-specific. Take Mypy for example:

_{(playgrounds: Mypy, Pyright)}

x1: int
x1 = 1235
reveal_type(x1)  # pyright => Literal[1235]
                 # mypy    => int

x2: int = 1235
reveal_type(x2)  # pyright => Literal[1235]
                 # mypy    => int

x3 = 1235
reveal_type(x3)  # pyright => Literal[1235]
                 # mypy    => int

x4 = 1233 + 2
reveal_type(x4)  # pyright => Literal[1235]
                 # mypy    => int

As far as I know, there is currently no setting to control this behaviour.