https://metacpan.org/pod/Graph::Easy http://bloodgate.com/perl/graph/manual/

graph.txt markup

For instance this input:

	[ Bonn ] -> [ Berlin ]
	[ Berlin ] -> [ Frankfurt ] { border: 1px dotted black; }
	[ Frankfurt ] -> [ Dresden ]
	[ Berlin ] ..> [ Potsdam ]
	[ Potsdam ] => [ Cottbus ]

would be rendered in ASCII as:

	+------+     +--------+      .............     +---------+
	| Bonn | --> | Berlin |  --> : Frankfurt : --> | Dresden |
	+------+     +--------+      .............     +---------+
	               :
	               :
	               v
	             +---------+     +---------+
	             | Potsdam | ==> | Cottbus |
	             +---------+     +---------+

The HTML or SVG output would look similiar except be more pretty :o)

output

It can output to ascii, boxart, svg, dot, and a html. The html and svg outputs aren't very useful, but the other ones are all great.

dot

This format is the format used by graphviz which is an extremely powerful graphing tool that can output to maney different formats (but can't do ascii or boxart).
graph-easy overview_graph.txt -as_dot | dot -Tsvg -o graph.svg

boxart

The boxart output mode uses unicode lines to draw a pretty great looking graph. I removed the dotted border option from the earlier example, it doesn't look as good in boxart.

graph-easy graph.txt -as_boxart
┌──────┐     ┌─────────┐     ┌───────────┐     ┌─────────┐
│ Bonn │ ──> │ Berlin  │ ──> │ Frankfurt │ ──> │ Dresden │
└──────┘     └─────────┘     └───────────┘     └─────────┘
               :
               :
               ∨
             ┌─────────┐     ┌───────────┐
             │ Potsdam │ ══> │  Cottbus  │
             └─────────┘     └───────────┘