Tuple types

The type Tuple[T1, …, Tn] represents a tuple with the item types T1, …, Tn:

def f(t: Tuple[int, str]) -> None:
    t = 1, 'foo'    # OK
    t = 'foo', 1    # Type check error

A tuple type of this kind has exactly a specific number of items (2 inthe above example). Tuples can also be used as immutable,varying-length sequences. You can use the type Tuple[T, …] (witha literal … – it’s part of the syntax) for thispurpose. Example:

def print_squared(t: Tuple[int, ...]) -> None:
    for n in t:
        print(n, n ** 2)
 
print_squared(())           # OK
print_squared((1, 3, 5))    # OK
print_squared([1, 2])       # Error: only a tuple is valid

Note

Usually it’s a better idea to use Sequence[T] instead of Tuple[T, …], asSequence is also compatible with lists and other non-tuple sequences.

Note

Tuple[…] is valid as a base class in Python 3.6 and later, andalways in stub files. In earlier Python versions you can sometimes work around thislimitation by using a named tuple as a base class (see section Named tuples).