Hi Flyte Community 👋, I have encountered an issue when using

map_task

and

partial

with different

list

objects. If there is a better way to do this behaviour please let me know. When using

partial

to prepare a function for a

map_task

if you partially fill in a

list

object the map task requires that the list you are mapping over is the same length as the list you are partially filling with the following error:

all maptask input lists must be the same length

. I don't think this should be expected behaviour as I am not running the

map_task

over both lists. An example workflow is below:

from functools import partial

from flytekit import map_task, task, workflow


@task
def add(a_list: list[int], b: int) -> list[int]:
    return [a + b for a in a_list]


@workflow
def adding_many_wf(a_list: list[int] = [1, 2, 1], b_list: list[int] = [1, 2, 3]) -> list[list[int]]:
    part_add = partial(add, a_list=a_list)
    output = map_task(part_add)(b=b_list)

    return output

So long as

a_list

and

b_list

in the above workflow are the same length it will run. If

b_list

is

[1, 2]

then it will error with the above. Any help would be greatly appreciated. Thanks.

@Christopher Wilson, an issue has already been created to tackle this: https://github.com/flyteorg/flyte/issues/4325.

Thank you for pointing me in the right direction!