tenspec

Declare what an array must be, beside the value it describes, and check it at one boundary.

Tenspec moves the shape and dtype checks from the top of a function into its signature, where a reader and a type checker both see them. It accepts or refuses the array the caller passed. It converts nothing, moves nothing, and copies nothing, unless the declaration names a transform that copies.

This is an early release, at version 0.2.0. The interface can change before version 1.0.

Install

Install it with pip, or with uv. Either one is enough, so run the line for the tool you use:

pip install "tenspec[numpy]"   # or: uv add "tenspec[numpy]"

Name the array library you need as an extra: numpy or torch. import tenspec loads neither one. It needs Python 3.13 or newer.

What it gives you

• Ordinary types. A declaration is an ordinary annotation carrying your backend's array type, so a type checker reads it and untouched code still runs. The checkers, the settings they need and their measured limits are on Type checkers and Ruff.
• Pydantic boundaries, natively. TensorContracts relates the fields of your own model inside one model validation.
• Runtime checks are opt in. An annotation alone performs no runtime work.
• Transforms are explicit. A value changes only when a declaration names a transform, and the runtime verifies the result kept its class, shape, native dtype and device.

The three entry points

from typing import Literal as Shape

import numpy as np

from tenspec import checked
from tenspec.numpy import Float


@checked
def weigh_columns(
    values: Float[Shape["rows features"]], weights: Float[Shape["features"]]
) -> Float[Shape["rows features"]]:
    return values * weights


print(weigh_columns(np.ones((3, 4)), np.array([1.0, 2.0, 3.0, 4.0])).shape)

weights must cover as many features as values has columns. A disagreement is a run-time refusal naming the axis, both extents, and the bindings the boundary held.

No type checker compares two shapes. A shape that disagrees is a run-time refusal, never a static error.

Documentation

The documentation site holds the guide, the API reference and two executed tutorials. The repository holds the source.

Attribution

The shape notation follows jaxtyping, which is MIT licensed. jaxtyping is not a dependency of this package.

License

MIT. See LICENSE.