Hello! I am thinking about writing a system, using which it is possible to store information about the structure of a bureaucratic system.    Coarse-grained features of the program include:    1) The program should allow the user to enter the hierarchy (like: authority X has a board of Y members, each of them has Z departments under his/her control etc) of a governmental organization    2) The program should visualize the hierarchy in form of a tree    3) It should be possible to enter information about what areas of public administration a particular civil servant is responsible for. In other words: If things go wrong in some domain, controlled by the government, the user should be able to figure out, who is responsible for that mess.    My first idea was to use a relational database for storing this information. However, a relational database may be inefficient due to the complexity of the data structure. At the moment, I think that it makes more sense to store the data in form of facts (not tables as in relational database). I mean that one is able to enter statements like (this is PROLOG syntax) isOrganization(X). hasBoard(X, Members) :- isOrganization(X), isList(Members). civilServant(X). isResponsibleFor(X, Y) :- civilServant(X), domain(Y). and then run queries, using which one can find out, which organizations are there, what members they have etc. Can one do this in Haskell? Thanks in advance Dmitri Pissarenko