Ordering of states in LPN

[sdwfrost]

When I make a labelled Petri net, the transition names come out in order of declaration but the state names appear to be in the order that they appear in the transitions, not in the type passed to the @relation.

epi_transitions = LabelledPetriNet(
  [:Pop],
  :infection=>((:Pop, :Pop)=>(:Pop, :Pop)),
  :exposure=>(:Pop=>:Pop),
  :recovery=>(:Pop=>:Pop))
seir_uwd = @relation () where (S::Pop, E::Pop, I::Pop, R::Pop) begin
    infection(S, I, E, I)
    exposure(E, I)
    recovery(I, R)
end
seir_acst = oapply_typed(epi_transitions, seir_uwd, [:β , :σ, :γ])
seir_lpn = dom(seir_acst) # Extract labelled Petri net
snames(seir_lpn)

Gives:

4-element Vector{Symbol}:
 :S
 :I
 :E
 :R

Is it possible to maintain the order of the states to that declared in the tuple?

I have a similar issue when making a UWD programmatically.

function make_age_classes(K, prefix="a")
    # Start with a blank UWD with K populations
    uwd = RelationDiagram(repeat([:Pop], K))
    # Build junctions (just a `Dict`), with the side effect of updating the UWD
    # `junctions` will be as follows similar to the following
    # Dict{Symbol, Int64} with n entries:
    #   :a_1 => 1
    #   :a_2 => 2
    junctions = Dict(begin
        variable = Symbol(prefix * "$(i)")
        junction = add_junction!(uwd, :Pop, variable=variable)
        set_junction!(uwd, port, junction, outer=true)
        variable => junction
    end for (i, port) in enumerate(ports(uwd, outer=true)))
    
    # This generates all combinations of the keys
    # Here, this will be a matrix of all pairs of keys
    pairs = collect(Iterators.product(keys(junctions), keys(junctions)))
    # This creates an empty vector to store the transition names in
    tnames = Vector{Symbol}(undef,0)
    ## Cycle through pairs and add boxes for infection
    for pair in pairs
        # We need 4 entries in the tuple as :infection is defined as infection(S, I, I, I)
        ins_outs = (pair[1], pair[2], pair[1], pair[2])
        # In the below, [junction_type(uwd, junctions[p]) for p in ins_outs] is just a vector of 4 :Pop
        box = add_box!(uwd, [junction_type(uwd, junctions[p]) for p in ins_outs], name=:infection)
        for (rgn, port) in zip(ins_outs, ports(uwd, box))
            set_junction!(uwd, port, junctions[rgn])
        end
        # This adds the names (as `Symbol`s) to the vector of transition names
        push!(tnames,Symbol("$(pair[1])_$(pair[2])"))
    end
    ## Generate an ACSet transformation using the above `epi_transitions`
    act = oapply_typed(epi_transitions, uwd, tnames)
    return act
end
K=3
age_acst = make_age_classes(K)
age_lpn = dom(age_acst)
snames(age_lpn)

Gives:

3-element Vector{Symbol}:
 :a2
 :a3
 :a1

Where does this order come from?