In the constraint rule:

[[ d@Def(Pub(), _, _) ^ (s_pub, s_prv) ]] := 
  Def [[ d ^ (s_pub, s_prv, s_pub) ]]

d is being traversed over twice, and this is not yet supported by the constraint generator. The result is that the named constraint rule Def is never executed, while I expect it to be executed.

Submitted by Gabriël Konat on 27 January 2017 at 12:37

There are no plans to support this, because multiple traversals have problems with associating meta-data to AST nodes. There is an idea to allow split rule definitions, that are merged later. However, these split rules should still result in a single traversal, so I’m closing this issue.