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Feasability of fork topology without `split`

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
cpp
Domain
backend

Research direction

Start by reviewing the topology and the split-based example in the issue, then read P3682 to understand the proposed removal of std::execution::split. Determine whether the shared-node graph can be represented using the remaining stdexec facilities without another dependency; done means providing a viable representation or documenting why it is not possible.

Written by the indexing model from the issue text.

Description

We'd like to represent the following topology (each node represents some work):

graph TD
    A --> B
    A --> C
    B --> D
    C --> D
    C --> E

    D --> END
    E --> END

It seems that for such a case, it is possible to use split:

auto A = just() | then(...) | split();

auto B = A | then(...);
auto C = A | then(...) | split();

auto D = when_all(B, C) | then(...);
auto E = C | then(...);

sync_wait(when_all(D, E));

However, P3682 (written by @RobertLeahy) proposed to remove std::execution::split and as far as we understand it, it was approved.

Therefore, how would we represent the above topology, without introducing other dependencies ?

Joint question with @maartenarnst.

Dominant language
C++
Stars
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Forks
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Avg merge
2d 16h
Merged PRs (30d)
43

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