Either Monad only for study purposes now.
Use the package manager pip to install zeither.
pip install zeitherfrom zeither import Either, left, right, is_either
either = Either(1)
assert either.map(lambda n: n + 1).value == 2
either = right('foo')
assert either.map(lambda prefix: prefix + 'bar').value == 'foobar'
either = left(ValueError('exception'))
assert either.left_map(lambda error: True if isinstance(error, ValueError) else False).value == True
either = right(1)
assert either.bind(lambda n: right(n + 1)).value == 2
either = left(1)
assert either.bind(lambda n: right(n + 1)).value == 1
assert is_either(either) == TruePull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
Please make sure to update tests as appropriate.