Python Built-in Types

Python has the following built-in types available at the global scope.

Bool

An object referencing one of two possible values: True and False.

Variables instantiated as bool are mutable but the boolean values themselves are immutable.

ByteArray

A mutable bytes object. The following are equivalent declarations:

ba = bytearray(b'...'))
ba = bytearray([46, 46, 46]).

Note that iterating over a bytearray yeilds int values, not byte values.

In the context of type annotations, try:

ba: bytes = bytearray(b'abc'))

Bytes

In the context of type annotations, try:

b: bytes = b"abc"

Complex

A complex number stored as real and imaginary components.

z = complex(-2.0, 0.0)
z == z.real + z.imag*1j

See the cmath module for doing math with complex numbers.

Dict

In the context of type annotations, try:

d: dict[str, int] = {"1": 1}

Float

A floating point number.

There are also the IEEE 754 special values:

• float("NaN") representing not a number

• float("inf") representing positive infinity

• float("-inf") representing negative infinity

In the context of type annotations, try:

f: float = 3.14

FrozenSet

In the context of type annotations, try:

def __init__(self) --> None:
    self._options: frozenset[str] = frozenset([1, 2])

Int

In the context of type annotations, try:

i: int = 0

List

In the context of type annotations, try:

l: list[str] = ["ham", "spam"]

MemoryView

An interface into internal memory of objects.

In the context of type annotations, try:

mv: bytes = memoryview(obj)

Set

In the context of type annotations, try:

s: set[str] = set(["A", "B", "A"])

Str

In the context of type annotations, try:

s: str = "abc"

A list of methods for str objects can be seen here.

Tuple

In the context of type annotations, try:

single: tuple[int] = [1]
double: tuple[int, int] = [1, 2]
nple: tuple[int, ...] = [1, 2, 3, 4, 5]

The tuple[T, ...] annotation checks for homogenous typing. To allow for a a variable number of any values, try:

from typing import Any

something: tuple[Any, ...] = [1, "1"]

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