liblaf-jarp 0.2.1

liblaf.jarp helps when JAX code mixes traceable arrays with ordinary Python metadata, and when the same program needs to cross into NVIDIA Warp. It is usually imported as from liblaf import jarp and packages a few focused tools around that boundary:

• filter_jit and fallback_jit wrap callables while partitioning arrays away from static metadata.
• Enum, define, frozen, array(), static(), and auto() make enum state and attrs classes flatten the way JAX expects.
• ravel turns the dynamic leaves of a tree into one flat vector and returns a reusable Structure for round trips.
• tree.where and tree.select apply jax.numpy.where and jax.numpy.select across matching PyTree leaves.
• jarp.lax retries a small slice of jax.lax eagerly when JAX rejects Python-only callback logic, while preserving the wrapped primitive metadata.
• to_warp, jarp.struct, jarp.warp.jax_callable, and jarp.warp.jax_kernel cover the common JAX-to-Warp interop paths.

📦 Installation

[!NOTE] liblaf-jarp requires Python 3.12 or newer.

Install the published package with uv:

uv add liblaf-jarp

If you want a CUDA-enabled JAX extra, pick the matching wheel set:

uv add 'liblaf-jarp[cuda12]'
uv add 'liblaf-jarp[cuda13]'

🚀 Quick Start

This example shows the core workflow: define a mixed data-and-metadata PyTree once, then reuse the same split at the function boundary.

import jax.numpy as jnp
from liblaf import jarp


@jarp.define
class Batch:
    values: object = jarp.array()
    label: str = jarp.static()


@jarp.filter_jit
def normalize(batch: Batch) -> Batch:
    centered = batch.values - jnp.mean(batch.values)
    return Batch(values=centered, label=batch.label)


batch = Batch(values=jnp.array([1.0, 2.0, 3.0]), label="train")
result = normalize(batch)

The array payload stays on the dynamic side of the partition, while the string label remains static metadata. auto() is the middle ground when a field should follow the runtime value.

Enum state can stay dynamic too, which is useful for state machines inside JAX control flow:

import enum

import jax.numpy as jnp
from liblaf import jarp


class Phase(jarp.Enum):
    START = enum.auto()
    RUNNING = enum.auto()


phase = Phase.where(jnp.array([True, False]), Phase.START, Phase.RUNNING)

jarp.ravel handles the other common workflow: flatten only the dynamic leaves into one vector and keep enough structure around to rebuild the tree later.

import jax.numpy as jnp
from liblaf import jarp


payload = {"a": jnp.zeros((3,)), "b": jnp.ones((4,)), "static": "foo"}
flat, structure = jarp.ravel(payload)
round_trip = structure.unravel(flat)

When a JAX or NumPy pipeline needs to cross into Warp, jarp.to_warp can infer vector and matrix dtypes from trailing dimensions:

from typing import Any

import jax.numpy as jnp
from liblaf import jarp


arr_wp = jarp.to_warp(jnp.zeros((5, 3), jnp.float32), (-1, Any))

For Warp structs whose field dtypes should follow the surrounding JAX precision mode, jarp.struct can specialize annotations from a small factory:

from typing import Any

import warp as wp
from liblaf import jarp


@jarp.struct
class Particle[T]:
    @classmethod
    def __annotations_factory__(cls, dtype: Any) -> dict[str, Any]:
        return {
            "position": wp.array1d(dtype=wp.types.vector(3, dtype)),
            "mass": wp.array1d(dtype=dtype),
        }


particles64 = Particle[wp.float64]()
particles_default = Particle()

Particle() uses jarp.warp.types.floating, so it follows JAX's active jax_enable_x64 setting.

When JAX control-flow primitives reject Python-only callback logic, jarp.lax.cond, switch, fori_loop, and while_loop try the corresponding jax.lax primitive first. If that call raises one of the selected JAX tracing or indexing errors, the wrapper logs the error, caches the failed metadata signature, and reruns the fallback eagerly.

For broader PyTree traversal helpers, see jarp.PyTreeProxy, jarp.partial, jarp.tree.register_generic, and the lower-level jarp.tree.codegen module. Importing jarp.tree also registers the built-in PyTree adapters for bound methods and warp.array.

🛠️ Local Development

Clone the repository, sync the workspace, and use nox for the maintained automation surface:

git clone https://github.com/liblaf/jarp.git
cd jarp
uv sync --all-groups
nox --list-sessions
nox --tags test

To build the documentation site locally:

uv run zensical build

📚 Documentation

• Documentation site
• Getting started guide
• Call wrappers guide
• PyTree workflows
• Warp interop guide
• API reference

🤝 Contributing

Issues and pull requests are welcome, especially around PyTree ergonomics, Warp integration, and edge cases that show up in real JAX code.

🔗 Links

• Documentation
• Changelog
• PyPI
• Issues

📝 License

Copyright © 2026 liblaf.
This project is MIT licensed.