Trees to sub-streams conversion

[emil14]

Classical FBP has trees. Questions are:

1. Should we implement them?

• What are use cases for trees?
• What are ways to solve those cases without trees?

2. How they could be implemented?

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(Un)packing trees

In FBP it's possible to "(diz)assemble" trees

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Sub-stream linear form

In FBP this tree

Could be linearized to this sub-stream:

<X <Y Z> W>

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Related to #35

[emil14]

Off topic (on batch-based structures and nested sub-streams)

just as a though. It's no problem with nested sub streams from point of view of a type system as long as they are single-typed. As soon as we have things like ( (42 'john') (27 'jessy') 'fighers' ) to represent e.g. { name string, users []{name string, age int} } it becomes problem:

One way to achieve this is to use unions (if they will be allowed to use like that, see #130) and have very hard-to-understand typings like t = open | close | string | number that barely represents the stream structure

Other way is to give up on nested sub-stream for such cases and use batch-based structures like tuple or record:

( [42 'john'] [27 'jessy'] 'fighers' )

so t = [int, string] | string which is still bad but a bit better

[emil14]

We have normal structures