Hi all, I have a few questions about heap-allocated memory pointers in GHC. Both code and data live in the heap, and both can have pointers to other objects. However, according to my understanding, most heap-allocated objects would be immutable. Moreover even if objects might be mutated, most pointers should not be updated. I have heard that the runtime system might implement several features by updating pointers, but I am not sure which features are they. My question is thus: (1) is there a way to trace mutations of heap objects (for instance by modifying the GC system code) [I don't need to know what is the change, all I want to know is what has been changed], and (2) is there a way where I could trace pointer updates [in this case I'd like to know both the old and objects, preferably by name]? More specifically, are these possible by annotating/changing the runtime system only (i.e. not touching code generation)? Thanks, Ray Department of Computer Science Tufts University