Edges with no source for circuit diagrams

[bjourne]

Hi all. MWE:

box: "Full Adder"
inp: "" {
    style.stroke-width: 0
    style.fill: white
    width: 0
    height: 0
}
out: "" {
    style.stroke-width: 0
    style.fill: white
    width: 0
    height: 0
}
inp -> box: "carry in"
out: ""
box -> out: "carry out"

As you can see, I'm trying to create a diagram for a full adder. For that I need edges that are "external" and have no source vertex associated with them. Or a source vertex that is just a dot and not a box. Is something like this possible to accomplish in D2?

[alixander]

@bjourne you can just set it to a small circle. Does that work for your use case?

https://play.d2lang.com/?script=TM0xysMwDAXgXad4eP9_2tVDoUvv4diiFog42A5NKbl7sbx006cn8aKG1rh5fAhIpc8BaDls7BGlRmXbaFhYPZwzvST17HG9mDLLM3cjASedREs5PNxjV8U9Ja6OZN3-rc6PIip7_6WsG_5umG8x1PqGrG5cWedSjhFPzrjs3dE3AAD__w%3D%3D&

[bjourne]

Thanks, but honestly it doesn't look that great.

[alixander]

Can you draw out what you're looking for?

[bjourne]

I want to draw a diagram like this. As you can see many of the arrows points to or from labels and not boxes.