Literal

Special typing form to define “literal types”.

Syntax

PYTHON Copy

typing.Literal

Examples

Example 1

PYTHON Copy

def validate_simple(data: Any) -> Literal[True]:   always returns True
    ...

Mode: TypeAlias = Literal['r', 'rb', 'w', 'wb']
def open_helper(file: str, mode: Mode) -> str:
    ...

open_helper('/some/path', 'r')       Passes type check
open_helper('/other/path', 'typo')   Error in type checker

See Also

TypeError hashable