'data-reify' provided the ability to turn recursive structures into explicit graphs. Many (implicitly or explicitly) recursive data structure can be given this ability, via a type class instance. This gives an alternative to using Ref for observable sharing. Observable sharing in general is unsafe, so we use the IO monad to bound this effect, but can be used safely even with unsafePerformIO if some simple conditions are met. Typically this package will be used to tie the knot with DSL's that depend of observable sharing, like Lava. Providing an instance for MuRef is the mechanism for allowing a structure to be reified into a graph, and several examples of this are provided. © 2009 Andy Gill; BSD3 license.