From a30e2237f0a1077336bcf7e37b57332c497e1f2d Mon Sep 17 00:00:00 2001
From: Giuseppe Carleo <28149892+gcarleo@users.noreply.github.com>
Date: Thu, 19 Mar 2026 20:38:01 +0100
Subject: [PATCH] Handle new JAX bind params API

---
 folx/interpreter.py      | 37 ++++++++++++++++++++++++++++---
 test/test_interpreter.py | 48 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+), 3 deletions(-)
 create mode 100644 test/test_interpreter.py

diff --git a/folx/interpreter.py b/folx/interpreter.py
index 3cc9380..db5f03e 100644
--- a/folx/interpreter.py
+++ b/folx/interpreter.py
@@ -1,5 +1,6 @@
 import functools
 import logging
+import re
 import warnings
 from collections import defaultdict
 from typing import TYPE_CHECKING, Callable, ParamSpec, Sequence, TypeVar
@@ -44,6 +45,36 @@
 P = ParamSpec('P')
 
 
+def _version_key(version: str) -> tuple[int, ...]:
+    return tuple(
+        int(match.group(0))
+        for part in version.split('.')
+        if (match := re.match(r'\d+', part)) is not None
+    )
+
+
+_USES_DICT_BIND_PARAMS = _version_key(jax.__version__) >= (0, 9, 2)
+
+
+def _split_bind_params(primitive, params):
+    """Normalize JAX primitive bind params across old and new JAX APIs."""
+
+    bind_params = primitive.get_bind_params(params)
+    if _USES_DICT_BIND_PARAMS:
+        if not isinstance(bind_params, dict):
+            raise TypeError(
+                'Expected primitive.get_bind_params() to return a dict for '
+                f'JAX >= 0.9.2, got {bind_params!r}.'
+            )
+        return (), bind_params
+    if not isinstance(bind_params, tuple) or len(bind_params) != 2:
+        raise TypeError(
+            'Expected primitive.get_bind_params() to return a 2-tuple for '
+            f'JAX < 0.9.2, got {bind_params!r}.'
+        )
+    return bind_params
+
+
 class JaxExprEnvironment:
     # A simple environment that keeps track of the variables
     # and frees them once they are no longer needed.
@@ -169,7 +200,7 @@ def eval_pjit(eqn: JaxprEqn, invals):
         )
 
     def eval_custom_jvp(eqn: JaxprEqn, invals):
-        subfuns, args = eqn.primitive.get_bind_params(eqn.params)
+        subfuns, args = _split_bind_params(eqn.primitive, eqn.params)
         fn = functools.partial(eqn.primitive.bind, *subfuns, **args)
         with LoggingPrefix(f'({summarize(eqn.source_info)})'):
             return wrap_forward_laplacian(fn)(
@@ -177,7 +208,7 @@ def eval_custom_jvp(eqn: JaxprEqn, invals):
             )
 
     def eval_laplacian(eqn: JaxprEqn, invals):
-        subfuns, params = eqn.primitive.get_bind_params(eqn.params)
+        subfuns, params = _split_bind_params(eqn.primitive, eqn.params)
         with LoggingPrefix(f'({summarize(eqn.source_info)})'):
             fn = get_laplacian(eqn.primitive, True)
             return fn(
@@ -189,7 +220,7 @@ def eval_laplacian(eqn: JaxprEqn, invals):
         # Eval expression
         try:
             if all(not isinstance(x, FwdLaplArray) for x in invals):
-                subfuns, bind_params = eqn.primitive.get_bind_params(eqn.params)
+                subfuns, bind_params = _split_bind_params(eqn.primitive, eqn.params)
                 # If non of the inputs were dependent on an FwdLaplArray,
                 # we can just use the regular primitive. This will avoid
                 # omnistaging. While this could cost us some memory and speed,
diff --git a/test/test_interpreter.py b/test/test_interpreter.py
new file mode 100644
index 0000000..ea0995a
--- /dev/null
+++ b/test/test_interpreter.py
@@ -0,0 +1,48 @@
+import pytest
+
+import folx.interpreter as interpreter_mod
+
+
+class _DummyPrimitive:
+    def __init__(self, result):
+        self.result = result
+
+    def get_bind_params(self, params):
+        assert params == {'x': 1}
+        return self.result
+
+
+def test_split_bind_params_accepts_legacy_tuple(monkeypatch):
+    monkeypatch.setattr(interpreter_mod, '_USES_DICT_BIND_PARAMS', False)
+    subfuns, params = interpreter_mod._split_bind_params(
+        _DummyPrimitive((['fn'], {'x': 2})), {'x': 1}
+    )
+    assert subfuns == ['fn']
+    assert params == {'x': 2}
+
+
+def test_split_bind_params_accepts_new_dict_only_api(monkeypatch):
+    monkeypatch.setattr(interpreter_mod, '_USES_DICT_BIND_PARAMS', True)
+    subfuns, params = interpreter_mod._split_bind_params(
+        _DummyPrimitive({'x': 2}), {'x': 1}
+    )
+    assert subfuns == ()
+    assert params == {'x': 2}
+
+
+def test_split_bind_params_rejects_invalid_tuple_shape(monkeypatch):
+    monkeypatch.setattr(interpreter_mod, '_USES_DICT_BIND_PARAMS', False)
+    with pytest.raises(TypeError, match='2-tuple'):
+        interpreter_mod._split_bind_params(_DummyPrimitive(({'x': 2},)), {'x': 1})
+
+
+def test_split_bind_params_rejects_dict_on_legacy_jax(monkeypatch):
+    monkeypatch.setattr(interpreter_mod, '_USES_DICT_BIND_PARAMS', False)
+    with pytest.raises(TypeError, match='JAX < 0.9.2'):
+        interpreter_mod._split_bind_params(_DummyPrimitive({'x': 2}), {'x': 1})
+
+
+def test_split_bind_params_rejects_tuple_on_new_jax(monkeypatch):
+    monkeypatch.setattr(interpreter_mod, '_USES_DICT_BIND_PARAMS', True)
+    with pytest.raises(TypeError, match='JAX >= 0.9.2'):
+        interpreter_mod._split_bind_params(_DummyPrimitive((['fn'], {'x': 2})), {'x': 1})