I've inherited some Haskell code, which you can find here: http://web.cecs.pdx.edu/~mpj/pubs/aug.html The text of the accompanying paper says, "we extend the Text class..." -- but the identifier "Text" appears nowhere in the code. Is this just an error in the paper, or is the Text class getting involved in some indirect way, e.g. through String or perhaps because of the line "instance Show Tree where . . ."? Regards, Michael Turner Executive Director Project Persephone 1-25-33 Takadanobaba Shinjuku-ku Tokyo 169-0075 Mobile: +81 (90) 5203-8682 turner@projectpersephone.org Understand - http://www.projectpersephone.org/ Join - http://www.facebook.com/groups/ProjectPersephone/ Donate - http://www.patreon.com/ProjectPersephone Volunteer - https://github.com/ProjectPersephone "Love does not consist in gazing at each other, but in looking outward together in the same direction." -- Antoine de Saint-Exupéry