category-theory

In the following diagram, it is not possible to drag Y on to the end of the arrow, despite it being empty.

In such a situation, it makes sense to allow Y to be dragged on top of the empty node.

The default show method dumps all the type information and is therefore very unreadable.

Complete algorithm: http://web.cecs.pdx.edu/~mpj/pubs/polyrec.html

We can already draw arbitrary permutations as sequences of swaps, but this can clutter diagrams unnecessarily.
An easy fix is to define Permutation boxes, with an appropriate refactoring of the drawing module.

These could then be constructed by calling diagram.permute as proposed in issue oxford-quantum-group/discopy#17.

One design decision that needs to be tak

• untabify
• indent
• align where needed