I wrote (back in November):
Currently, all implementations provide either the 'unsafeCoerce' or 'unsafeCoerce#' functions, but they live in implementation-specific locations. This proposal is to adopt the Haskell'98-compatible name 'unsafeCoerce', and to add it to the standard base library package.
Discussion finished, with a general feeling that this would be a good thing. There were some objections from Iavor (and others) that the behaviour of 'unsafeCoerce' is entirely implementation-dependent. Others replied, yes, indeed, but it _is_ marked "unsafe". The proposal merely makes the same name available in all compilers (to avoid the need for CPP), but gives no guarantees about its effects. You must satisfy yourself about whether any given usage is safe or not, with any given compiler. So I have just pushed a patch for this. The final location chosen in the module hierarchy was Unsafe.Coerce. Regards, Malcolm