Flexible function inputs
Accept lists, tuples, ranges, generators, and other iterable inputs without requiring a concrete container.
Python · Type Alias
Iterable
collections.abc.Iterable[T] annotates an object that can provide values of type T one at a time. It is the modern replacement for the deprecated typing.Iterable alias.
- Since
- 3.9
How it works
Iterable[T] describes an object that can provide values of type T one at a time. Use the generic form from collections.abc in modern Python annotations; it can describe inputs such as lists, ranges, generators, and other iterable objects.
Syntax
collections.abc.Iterable[T]Parameters
| Name | Type | Description |
|---|---|---|
T | type parameter | The element type yielded by the iterable. |
Returns
An iterable object yielding values of the declared type; Iterable[T] is used in annotations rather than producing a runtime value.
Key points
- Modern annotations should import
Iterablefromcollections.abc. - A generator that only yields values can be annotated with
Iterable[YieldType]. - The type is parameterized with square brackets, such as
Iterable[int].
Common mistakes
typing.Iterableis deprecated; importIterablefromcollections.abcinstead.
Example: Annotate a function accepting iterable integers
from collections.abc import Iterable
def total(values: Iterable[int]) -> int:
return sum(values)
print(total([1, 2, 3]))
print(total(range(4)))The function accepts any iterable of integers, including a list and a range.
When to use it
Generator return annotations
Describe the values yielded by a generator that only produces items.
Reusable type aliases
Build generic aliases whose element type is preserved.
Related
collections.abc.Iterablecollections.abc.Iteratortyping.Iteratoriter()for