[akka-user][deprecated] Stream loops

[Beno]

Hello,

I have seen threads on this forum where Akka team recommends trying to
avoid stream loops ("they are tricky"). I have a use case where steams with
loops could be a solution to otherwise difficult problem.

the payload of the stream is a list of automatically formed case classes
from an input file, plus a wrapper case class with . at a given stage:

1. pop the next case class in the list and match {
case A --> do some stuff, pull some info out of A, set a field (i.e.
create new case object to preserve immutabilty) of the wrapper case class =
to a field of the A class, loop back to this stage with the list of case
classes not including A
case B --> do other stuff, add info from B to wrapper case class, loop
back to this stage with list of case classes not including B
.
.
.
} . // and the point here is there could be 0 to many As, Bs, Cs, etc
case F --> send to AthroughEExhaustedState

2. AthroughEExhaustedState might have its own similar rules

is this insanity? or am I missing a much better solution?
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[Brian Maso]

I've used loops before in Akka Streams. They are tricky, and debugging is
hard, but sometimes is the right fit. I think there is an analog to
recursion, though. Many things that can be expressed as a recursive loop
can also be expressed as an unfold, and that might be a better way of doing
it.

Brian Maso

Post by Beno
Hello,
I have seen threads on this forum where Akka team recommends trying to
avoid stream loops ("they are tricky"). I have a use case where steams with
loops could be a solution to otherwise difficult problem.
the payload of the stream is a list of automatically formed case classes
1. pop the next case class in the list and match {
case A --> do some stuff, pull some info out of A, set a field (i.e.
create new case object to preserve immutabilty) of the wrapper case class =
to a field of the A class, loop back to this stage with the list of case
classes not including A
case B --> do other stuff, add info from B to wrapper case class,
loop back to this stage with list of case classes not including B
.
.
.
} . // and the point here is there could be 0 to many As, Bs, Cs, etc
case F --> send to AthroughEExhaustedState
2. AthroughEExhaustedState might have its own similar rules
is this insanity? or am I missing a much better solution?
--
*****************************************************************************************************
** New discussion forum: https://discuss.akka.io/ replacing akka-user google-group soon.
** This group will soon be put into read-only mode, and replaced by discuss.akka.io
https://akka.io/blog/news/2018/03/13/discuss.akka.io-announced
*****************************************************************************************************

Read the docs: http://akka.io/docs/

http://doc.akka.io/docs/akka/current/additional/faq.html

Search the archives: https://groups.google.com/group/akka-user

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Post by Beno

Read the docs: http://akka.io/docs/
Check the FAQ: http://doc.akka.io/docs/akka/current/additional/faq.html
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