layout,syntax: Specify horizontal vs vertical arrangement

[alixander]

These should be scoped to containers. E.g. something like

arrangement: horizontal

a: {
  arrangement: horizontal
  ...
}
b: {
  arrangement: vertical
}

so a and b would be horizontal, the contents of a would be horizontal, and the contents of b would be vertical.

not sure arrangement is the best keyword here.

also for the value, other tools use LR and TD, which... is perhaps more descriptive, but less obvious to read. e.g. it wasn't clear to me for a long time that graphviz's graph TD wasn't just a header to be placed on every diagram and that it actually stood for top-down.

[prowave]

What about defining the relationship type in addition to the container layout?

peer is horizontal
hierarchical is vertical and the default

a: Node 1
b: Node 2
c: Node 3
d: Application

a <-> b <-> c {
  type: peer
}

d -> a 
d -> b
d -> c

Or some variant of the above that fits within your standards. :)

[alixander]

the ability to specify it on a relationship level is possible in TALA, since it's our custom engine and we can do anything, but I don't think that granularity is supported in dagre/graphviz/elk. it's a good idea, but we'll probably do the container one first since it's portable across layout engines. ty @prowave

[guybarnhartmagen]

I agree - this is an important feature, especially when having extensive diagrams

[alixander]

This should actually come after glob support. Because we want it to apply recursively.

e.g.

a: {
  # All descendants + this container will have vertical
  **.orientation: vertical
}

[alixander]

Actually, this will be out next release. However, there are no layout engines that support mixing arrangements, e.g. top level is vertical orientation and subgraph A is horizontal. See #251