Type Checking

Annotating and checking the physical dimension of an argument. For enabling runtime type checking and for dtype/shape annotations on the default Quantity, see the unxt Type Checking guide.

>>> import unxt as u
>>> import unxts.parametric as up

Dimension annotations for type checking

Because the dimension lives in the type, you can annotate function signatures with dimensioned ParametricQuantity types, and unxt’s runtime type checking (via jaxtyping) will enforce them. This dimension-level checking is what ParametricQuantity adds over the default Quantity (whose type carries only dtype and shape):

>>> from jaxtyping import Shaped, jaxtyped
>>> from beartype import beartype as typechecker

>>> @jaxtyped(typechecker=typechecker)
... def velocity(
...     x: Shaped[up.PQ["length"], "N"],
...     t: Shaped[up.PQ["time"], "N"],
... ) -> Shaped[up.PQ["speed"], "N"]:
...     return x / t

>>> x = up.PQ([2.], "m")
>>> t = up.PQ([1.], "s")

>>> velocity(x, t)
ParametricQuantity(Array([2.], dtype=float32), unit='m / s')

Passing a quantity of the wrong dimension raises at call time (under runtime type checking). The base class AbstractParametricQuantity and the concrete unxt.Quantity are not parametric — Quantity[<dimension>] does nothing and is informational only.