Components sensitive to substrams

[emil14]

I was thinking on https://github.com/nevalang/nevalang/discussions/280 and turns out it's not clear how to implement components that must be aware of sub-streams. Let's think of * component that multiplies numbers. There's several approaches to achieve that:

1. 2 inports, 1 outport - limited arity (binary), for more than 2 numbers have to chain like in conventional langs
2. array inports, 1 outport - N-arity but static. Number of inports (of numbers to multiply) must be known at compile-time. Impossible to compute result for dynamic input (dynamic length)
3. 1 vector (slice) inport, 1 outport - can solve dynamic data but a) we have to create vec for every task and b) not FBP way (vectors is "batch" processing). Note: we omit "regular inport with array type" (not to be confused with "array inport") as they have same problem of "staticness" like array-inport)
4. 1 sub-stream inport, 1 outport - Can solve dynamic data in a FBP-way but have to create sub-stream for every task

Looks like no.4 is the best (and idiomatic) solution but there are some questions.

What if I have a substream and I want (without breaking its structure) multiply its every element by 2? Not "multiply all of them from left to right and then multiply by 2" but just operate on every sub-stream item (which is BTW usual and important thing) and pass it further? Does FBP bible has the answer? Can we ask GPT?

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Note that this question is crucial for stdlib implementation but not the compiler/runtime itself

[emil14]

Array inports WITH Sub streams

The most generic form of + would be array inport that accepts sub-streams. This way we can some sub-streams from several places. This is also more complicated and there's still a question whether we want to be able to work with non-sub-stream elements at the same time

[emil14]

Array inports WITH optional Sub streams

To continue https://github.com/nevalang/nevalang/issues/281#issuecomment-1517282027

This (in theory) would allow to "sum all items from this sub-stream plus this non-sub-stream regular number coming from second array inport slot". There are questions ofc:

• What is the proper way to sync this mechanism? Probably every regular item per sub-stream? (UPD: sync depends on concrete component and SSItems MUST never be mixed with regular messages)
• This feels complicated
• In theory we can pass compiler check and somehow mix up sub-stream items with regular items in the same inport which is very-very bad (UPD: type-system (I think) should be able to prevent this, see related discussion)

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See #285

[emil14]

We have task for stdlib design and I don't see a reason to keep this issue open