Here's the list of changes in each released version.
Added an explicit condition hierarchy.
Fixed a bug where certain kinds of cycles were not correctly detected during topological sorting.
Fixed a bug for recent SBCL versions when creating a digraph without a custom hash function.
Added the arbitrary-vertex function to return an arbitrary vertex of
a digraph.
Fixed a bug in copy-digraph.
Added rootp and leafp predicates to check whether a vertex is a root/leaf in
a digraph.
Minor internal cleanup.
If you pass an invalid strategy argument to reachablep there will now be
a restart available to supply a new value, instead of just crashing and burning.
Initial version.