type-variables – Tarik Billa

What’s the difference between a constrained TypeVar and a Union?

June 14, 2023 by Tarik

T‘s type must be consistent across multiple uses within a given scope, while U‘s does not. With a Union type used as function parameters, the arguments as well as the return type can all be different: U = Union[int, str] def union_f(arg1: U, arg2: U) -> U: return arg1 x = union_f(1, “b”) # No … Read more

What are skolems?

February 14, 2023 by Tarik

To start with, a “rigid” type variable in a context means a type variable bound by a quantifier outside that context, which thus can’t be unified with other type variables. This works a great deal like variables bound by a lambda: Given a lambda (\x -> … ), from the “outside” you can apply it … Read more