# JAX v0.4.38 — JAX v0.4.38

- Product: JAX (https://whatsnew.fyi/product/jax)
- Vendor: Google
- Date: 2024-12-17
- Version: v0.4.38
- Original notes: https://github.com/jax-ml/jax/releases/tag/jax-v0.4.38
- Permalink: https://whatsnew.fyi/product/jax/releases/v0.4.38

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **added** — Add jax.tree.flatten_with_path and jax.tree.map_with_path as shortcuts of the corresponding tree_util functions
- **added** — Add jax.lax.split as a primitive version of jax.numpy.split that yields a more compact transpose during automatic differentiation
- **changed** — jax.export.export can be used for device-polymorphic export with shardings constructed with jax.sharding.AbstractMesh
- **deprecated** — Deprecate a number of APIs in the internal jax.core namespace
- **removed** — Remove jax.core.check_eqn, jax.core.check_type, jax.core.check_valid_jaxtype, and jax.core.non_negative_dim
- **removed** — Remove jax.lib.xla_bridge.xla_client and jax.lib.xla_bridge.default_backend
- **removed** — Remove jax.lib.xla_client._xla and jax.lib.xla_client.bfloat16
- **removed** — Remove jax.numpy.round_

* Changes:
  * `jax.tree.flatten_with_path` and `jax.tree.map_with_path` are added
    as shortcuts of the corresponding `tree_util` functions.

* Deprecations
  * a number of APIs in the internal `jax.core` namespace have been deprecated.
    Most were no-ops, were little-used, or can be replaced by APIs of the same
    name in `jax.extend.core`; see the documentation for {mod}`jax.extend`
    for information on the compatibility guarantees of these semi-public extensions.
  * Several previously-deprecated APIs have been removed, including:
    * from `jax.core`: `check_eqn`, `check_type`,  `check_valid_jaxtype`, and
      `non_negative_dim`.
    * from `jax.lib.xla_bridge`: `xla_client` and `default_backend`.
    * from `jax.lib.xla_client`: `_xla` and `bfloat16`.
    * from `jax.numpy`: `round_`.

* New Features
  * `jax.export.export` can be used for device-polymorphic export with
    shardings constructed with {func}`jax.sharding.AbstractMesh`.
    See the [jax.export documentation](https://jax.readthedocs.io/en/latest/export/export.html#device-polymorphic-export).
  * Added `jax.lax.split`. This is a primitive version of
    `jax.numpy.split`, added because it yields a more compact
    transpose during automatic differentiation.