Inspired by the pipeline operator (|>) in other languages, I tried to implement a function to imitate it. When I use reduce to implement it, it results in None somewhere along the way, but another one using loops works just fine.
from functools import partial, reduce
from pprint import pprint
def pipeline(data, *funcs):
res = data
for func in funcs:
res = func(res)
return res
def pipeline_v2(data, *funcs):
reduce(lambda arg, func: func(arg), funcs, data)
def main() -> None:
result = pipeline(
range(1, 11),
partial(map, lambda x: x + 1),
partial(filter, lambda x: x % 2 == 0),
)
pprint(f'Final result: {tuple(result)}')
pprint('---------------------------------------------------------------------------------------------')
result = pipeline_v2(
range(1, 11),
partial(map, lambda x: x + 1),
partial(filter, lambda x: x % 2 == 0),
)
pprint(f'Final result: {tuple(result)}')
if __name__ == "__main__":
main()
This is the output:
Final result: (2, 4, 6, 8, 10)
---------------------------------------------------------------------------------------------
Traceback (most recent call last):
File "pipeline_code.py", line 34, in <module>
main()
File "pipeline_code.py", line 30, in main
print(f'Final result: {tuple(result)}')
^^^^^^^^^^^^^
TypeError: 'NoneType' object is not iterable
Why does this happen? To me it seems like pipeline and pipeline_v2 do the same thing.