I'm not suggesting extending the ASCII art mechanism. I'm just suggesting that compared to the API shown in the first example, cairo makes simple line-art quite trivial to write as code.
Specific features that would make sense to have available rather than drawing art in an image editor:
Line width, to draw the chevron without having to draw two adjacent lines.
Specific features that would make sense to have available rather than drawing art in an image editor:
Line width, to draw the chevron without having to draw two adjacent lines.
Dotted/dashed lines.