Check return value in Py

Author: Shimuuar

src/Python/Inline/Literal.hs

@@ -167,9 +167,11 @@ instance FromPy Bool where
 
 instance (ToPy a, ToPy b) => ToPy (a,b) where
   basicToPy (a,b) = do
-    p_a <- basicToPy a
-    p_b <- basicToPy b
-    Py [CU.exp| PyObject* { PyTuple_Pack(2, $(PyObject* p_a), $(PyObject* p_b)) } |]
+    basicToPy a >>= \case
+      NULL -> pure NULL
+      p_a  -> basicToPy b >>= \case
+        NULL -> pure $ NULL
+        p_b  -> Py [CU.exp| PyObject* { PyTuple_Pack(2, $(PyObject* p_a), $(PyObject* p_b)) } |]
 
 instance (FromPy a, FromPy b) => FromPy (a,b) where
   basicFromPy p_tup = evalContT $ do

src/Python/Internal/Types.hs

@@ -17,12 +17,14 @@ module Python.Internal.Types
   , pattern INLINE_PY_OK
   , pattern INLINE_PY_ERR_COMPILE
   , pattern INLINE_PY_ERR_EVAL
+  , pattern NULL
   ) where
 
 import Control.Exception
 import Control.Monad.IO.Class
 import Data.Coerce
 import Data.Map.Strict           qualified as Map
+import Foreign.Ptr
 import Foreign.ForeignPtr
 import Foreign.C.Types
 import Language.C.Types
@@ -71,3 +73,8 @@ pattern INLINE_PY_OK, INLINE_PY_ERR_COMPILE, INLINE_PY_ERR_EVAL :: CInt
 pattern INLINE_PY_OK          = 0
 pattern INLINE_PY_ERR_COMPILE = 1
 pattern INLINE_PY_ERR_EVAL    = 2
+
+
+pattern NULL :: Ptr a
+pattern NULL <- ((== nullPtr) -> True) where
+  NULL = nullPtr