Self-edges only work on top or bottom

[DusterTheFirst]

When using an edge to point from a node to itself, with bend: 130deg the bend will come either out of the top of the bottom (depending on if bend is negative) however there does not seem to be a way to make the bend come out of the side, either left or right.

[Jollywatt]

There is a hack you can use which is why I've not bothered to add a new controller for this:

#import "@preview/fletcher:0.4.5": diagram, node, edge

#diagram({
  node((0,0), [Hello], stroke: 1pt, shape: circle)

  edge((0,-.1), (0,+.1), "-|>", bend: 120deg)

  let polar(r, theta) = (r*calc.cos(theta), r*calc.sin(theta))
  let theta = 45deg
  edge(polar(0.1, theta), polar(-0.1, theta), "-|>", bend: 130deg)
})

By adjusting the edge‘s vertices by small amounts, you change the angle of the line that connects them; this line is then bent into the final arc that you see.

I haven't thought of a good interface for this. We could add a loop-angle option to edge, but then it wouldn't make sense for non-loop edges, and edge() already has lots of options. I want to keep it simple. (Ideas are welcome!) At the very least, there should be some examples in the manual, though.