[IR] Graph composition

[justinchuby]

Make graph callable

Graph()(value, ...) -> value... creates a copy of Graph and connects the new values and initializers to the value's graph.

Or: Create a composition tool

I think option (1) is more intuitive.

[leshabirukov]

I understand it as Graph()(graph1, graph2, ...) -> composed_graph..., is it right?

connects the new values

is it about node inputs\outputs or graph inputs\outputs?

What if two initializers share name but not value?
Will it sort the result graph?
What it will do if cycle appeared?

[justinchuby]

It's more like

input = ir.Value()
output1 = some_graph(input)
output2 = some_other_graph(output1)
new_graph = ir.Graph([input], [output2])

[leshabirukov]

Aha, and usual name conflict resolution is used? ok.