Interpreter for Wiring Diagrams

[jpfairbanks]

@JeffBezanson wrote this little interpreter for string diagrams.

using Catlab
using Catlab.WiringDiagrams
using Base.Threads
function interpreter(prog)
    ws = wires(prog)
    bs = boxes(prog)
    channels = [ Channel(0) for _ in ws ]
    function put_value!(box, port, value)
        # put value into every wire from the given source
        for i in 1:length(ws)
            w = ws[i]
            if w.source.box == box && w.source.port == port
                put!(channels[i], value)
            end
        end
    end
    n_inputs = length(input_ports(prog))
    n_outputs = length(output_ports(prog))
    set_input!(port, value) = put_value!(-2, port, value)
    set_inputs!(values...) = foreach(i->set_input!(i, values[i]), 1:length(values::NTuple{n_inputs}))
    function channels_for_box(b, kind)
        if b == -1
            n = n_outputs
        elseif b == -2
            n = n_inputs
        else
            n = length(kind === :target ? bs[b].input_ports : bs[b].output_ports)
        end
        chans = Vector{Channel{Any}}(undef, n)
        for j in 1:length(ws)
            w = ws[j]
            if getfield(w, kind).box == b
                chans[getfield(w, kind).port] = channels[j]
            end
        end
        @assert all(isassigned(chans, i) for i in 1:length(chans))
        return chans
    end
    for i in 1:length(bs)
        n_box_outputs = length(bs[i].output_ports)
        input_chans = channels_for_box(i, :target)
        workfun = bs[i].value
        function execute(inputs)
            str = "calling $workfun"
            if !isempty(inputs)
                str *= " on " * join(inputs, ", ")
            end
            sleep(rand()*0.1)
            println(str); flush(stdout)
            for p in 1:n_box_outputs
                put_value!(i, p, "box $i result $p")
            end
        end
        @spawn while true
            inputs = Any[ take!(c) for c in input_chans ]
            execute(inputs)
        end
    end
    out_chans = channels_for_box(-1, :target)
    get_outputs!() = map(take!, out_chans)
    stop!() = foreach(close, channels)
    (; set_inputs!, get_outputs!, stop!)
end
# example:
# sim = interpreter(prog)
# sim.set_inputs!(1,2,3,4)
# sim.get_outputs!()

[jpfairbanks]

@JeffBezanson, is there a more up to date execution engine for DWDs? Based on the last call, we are planning to have our code for the demo use that engine

0. Create a presentation with all the type signatures
1. Create all the primitive julia functions
2. Create a DWD for how to assemble them
3. Invoke the execution engine with the DWD and a Dict{Symbol, Function} to run the demo