there are packages which use phantom types to express inheritance (subtype) relations. unfortunately i cannot find a simple example and seem to misunderstand something. can somebody help with the following simple example? i have a most general type Dated, a subtype Note and a subsubtype Task. i have only instances for Note and Task, but operations for tasks and dated. my primary question is: why should i have the contexts in the classes (the code compiles without them)? they do not say more than what is already expressed in the instance declarations. i do also not think that i have used phantom types properly (eg. gtk2hs uses phantom types differently). what would be the proper solution? would it work for cases with multiple inheritance? thank you! andrew class CDated a class CDated a => CNotes a class CNotes a => CTasks a instance CDated Task instance CDated Note instance CNotes Note instance CNotes Task instance CTasks Task class Dated n where datedop :: n -> n class Notes1 n where noteop :: n -> n class Tasks1 n where taskop :: n -> n data Note = Note Int data Task = Task Int instance CTasks x => Tasks1 x where taskop n = n instance CDated x => Dated x where datedop n = n t:: Task = Task 1 n :: Note = Note 1 tt = taskop t -- nt = taskop n -- compiler error -- as expected! tx = datedop t nx = datedop n