Version 0 of an SML/NJ Library for pretty-printing possibly infinite syntax trees is now available. It uses eXene and CML.
At the moment, the code is in basically final form, but there is very little documentation.
If you would like to be notified when new releases are made, please send an e-mail to alley.stoughton@icloud.com.
The library is described in the paper Infinite Pretty-printing in eXene.
The source of the library is available.