Mechanism to inform users to update nutpie

Author: ricardoV94

pymc/sampling/mcmc.py

@@ -13,6 +13,7 @@
 #   limitations under the License.
 
 import contextlib
+import importlib.metadata
 import importlib.util
 import inspect
 import logging
@@ -87,6 +88,16 @@
 
 NUTPIE_INSTALLED = importlib.util.find_spec("nutpie") is not None
 
+# Bump when PyMC starts using a feature that requires a newer nutpie release.
+# Installed versions below this still work via fallback paths but get a FutureWarning
+# the first time they are used in a `pm.sample` call.
+_NUTPIE_MIN_SUPPORTED = (0, 16, 8)
+_NUTPIE_VERSION: tuple[int, ...] | None = (
+    tuple(int(p) for p in importlib.metadata.version("nutpie").split(".")[:3])
+    if NUTPIE_INSTALLED
+    else None
+)
+
 
 sys.setrecursionlimit(10000)
 
@@ -365,6 +376,14 @@ def _sample_external_nuts(
             raise ImportError(
                 "nutpie not found. Install it with conda install -c conda-forge nutpie"
             )
+        if _NUTPIE_VERSION is not None and _NUTPIE_VERSION < _NUTPIE_MIN_SUPPORTED:
+            warnings.warn(
+                f"nutpie {'.'.join(map(str, _NUTPIE_VERSION))} is installed; "
+                f"support for nutpie < {'.'.join(map(str, _NUTPIE_MIN_SUPPORTED))} "
+                "is deprecated and will be removed in a future PyMC release.",
+                FutureWarning,
+                stacklevel=3,
+            )
         import nutpie
 
         if initvals is not None: