How do you make a self-referential arrow with diagrams?

Asked Apr 28 '17 at 00:30

Active Apr 28 '17 at 01:05

Viewed 199 times

I would like to do something like this:

p = p2 (0,0)
shaft = arc xDir (-5/6 @@ turn)
example = ( arrowBetween' (with & arrowShaft .~ shaft) p p)

But, of course, I get an error: "Scale by zero! Halp!"

I understand why this doesn't work with the existing implementation of arrowBetween', since it calls arrow', which scales the shaft by the difference between the endpoints. However, this should be possible. It's not that uncommon to see an arrow loop back around to where it started in diagrams.

edited Apr 28 '17 at 01:05

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asked Apr 28 '17 at 00:30

Joshua Meyers

http://projects.haskell.org/diagrams/doc/arrow.html there is an example in the section Connecting points on the trace of diagrams – epsilonhalbe Apr 28 '17 at 06:58
Right, but in this example the endpoints are merely close together. What if they are the same? – Joshua Meyers Apr 28 '17 at 07:37
There is an issue about this currently: https://github.com/diagrams/diagrams-lib/issues/151 – Joshua Meyers Apr 28 '17 at 07:39

How do you make a self-referential arrow with diagrams?

0 Answers0