I am trying to use the EdComb library on a Windows Operating System with Hugs98. http://www2-data.informatik.unibw-muenchen.de/EdComb/ I have a problem when loading the file ...\EdComb\Editor.lhs The message below appears after that FranTk is well loaded : Reading file "E:\EdComb\FranTkUtils.lhs": ERROR "E:\EdComb\FranTkUtils.lhs":21 - Undefined type constructor "Structured" I have searched in all the EdComb, FranTk and Hugs libraries the file in which this data structure (Structured) is defined in vain. I had the same problem when trying to play with the Oege de Moor's extensible structure editor, http://web.comlab.ox.ac.uk/oucl/work/oege.de.moor/ when loading the file ...\struct\Label.hs. The message below appears (FranTk is well loaded ) : Reading file "....\struct\ViewTypes.hs" ERROR "....\struct\ViewTypes.hs":9 - Undefined type constructor "Structured Can someone tell me what to do in the case? Thank you in advance