diamond_problem_with_types.py

import bonobo
from bonobo.util.bags import BagType
from bonobo_quirksmode.config import set_output_type


def generate():
    yield from ('a', 'b', 'c')

LetterBag = BagType('LetterBag', ['letter'])

@set_output_type(LetterBag)
def tolower(x):
    yield x.lower()

@set_output_type(LetterBag)
def toupper(x):
    yield x.upper()

def get_graph(**options):
    graph = bonobo.Graph()

    chain = graph.add_chain(
        generate,
        tolower,
        print,
    )

    graph.add_chain(
        toupper,
        _input=chain.input,
        _output=chain.output,
    )
    return graph


def get_services(**options):
    return {}


if __name__ == '__main__':
    with bonobo.parse_args() as options:
        bonobo.run(get_graph(**options), services=get_services(**options))