Hello, Is it possible to write a function that would display all the instances of a class currently in scope[1]? For example, for 'Show a' it should output something like: The instances of 'Show a' currently in scope are: Show Int Show Float Show Char Show ... Depending on what modules are imported at compile time, the list would grow or shrink. I am willing to accept all sorts of restrictions at this point in time such as: ~ Yes, but only if the classes are declared in this way (but not for ones declared in the standard library) ~ Yes, but it requires template haskell It is currently my belief that the compiler "knows" the answer, but there is no way to get the list from the compiler... I would be interested in any information, links, examples, papers, etc, that you can provide that would tell me: ~ Yes it can be done ~ It could be done with a compiler extension ~ It could never be done ~ It could be done, but it would be a really horrible idea, and here's why So don't hold back :) Thanks! Jeremy Shaw. [1] I suppose by 'currently in scope' I mean all the instances that type checker is considering when it type checks the function at compile time. But I am really not picky about what I mean right now as I can't get anything remotely ressembling this to happen.