support for GraphViz "HTML strings" for node or edge labels

[jmtd]

Hello!

GraphViz supports something called HTML-like labels for some objects. This can be useful for adding some mark-up to edge or node labels (e.g. fractions with <<SUP>1</SUP>/<SUB>2</SUB>2>). A HTML-like label is delimited with a pair of angle brackets instead of double-quotes. E.g.

digraph {
  1 [label="regular label"];
  2 [label=<<B>emboldened label</B>>];
  1 -> 2;
}

resulting in:

The current handling of attributes in Algebra.Graph.Export.Dot always wraps labels in double-quotes. It would be nice to be able to specify that the HTML-like format was to be used.

(I completely forgot about #44/#47 in the intervening years. I'll try to pick it back up)

[snowleopard]

@jmtd Hi there! Perhaps, we can make it possible to disable double-quoting by adding a new field to Style, e.g. called quoting with choices None and Double (with the latter being the default)?

(I completely forgot about #44/#47 in the intervening years. I'll try to pick it back up)

Yep, it would be great to finally merge #47!