deepset-ai · ZanSara · Nov 15, 2023 · Nov 15, 2023
diff --git a/canals/component/sockets.py b/canals/component/sockets.py
@@ -29,9 +29,18 @@ def __post_init__(self):
             # We need to "unpack" the type inside the Variadic annotation,
             # otherwise the pipeline connection api will try to match
             # `Annotated[type, CANALS_VARIADIC_ANNOTATION]`.
-            # Note Variadic is expressed as an annotation of one single type,
+            #
+            # Note1: Variadic is expressed as an annotation of one single type,
             # so the return value of get_args will always be a one-item tuple.
-            self.type = get_args(self.type)[0]
+            #
+            # Note2: a pipeline always passes a list of items when a component
+            # input is declared as Variadic, so the type itself always wraps
+            # an iterable of the declared type. For example, Variadic[int]
+            # is eventually an alias for Iterable[int]. Since we're interested
+            # in getting the inner type `int`, we call `get_args` twice: the
+            # first time to get `List[int]` out of `Variadic`, the second time
+            # to get `int` out of `List[int]`.
+            self.type = get_args(get_args(self.type)[0])[0]
 
 
 @dataclass

diff --git a/canals/component/types.py b/canals/component/types.py
@@ -1,4 +1,4 @@
-from typing import TypeVar
+    from typing import TypeVar, Iterable
 from typing_extensions import TypeAlias, Annotated  # Python 3.8 compatibility
 
 CANALS_VARIADIC_ANNOTATION = "__canals__variadic_t"
@@ -11,4 +11,4 @@
 # This type doesn't do anything else than "marking" the contained
 # type so it can be used in the `InputSocket` creation where we
 # check that its annotation equals to CANALS_VARIADIC_ANNOTATION
-Variadic: TypeAlias = Annotated[T, CANALS_VARIADIC_ANNOTATION]
+Variadic: TypeAlias = Annotated[Iterable[T], CANALS_VARIADIC_ANNOTATION]
diff --git a/sample_components/sum.py b/sample_components/sum.py
@@ -10,6 +10,6 @@ class Sum:
     @component.output_types(total=int)
     def run(self, values: Variadic[int]):
         """
-        :param value: the value to check the remainder of.
+        :param value: the values to sum.
         """
-        return {"total": sum(values)}  # type: ignore
+        return {"total": sum(values)}