#7662: Improve GC of mutable objects -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Runtime System | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by dobenour): MLton does manage to unpack refs in records though. I think that it can be done in general IF you either: - support interior pointers in the GC (which GHC probably doesn't). - represent mutable refs as "fat pointers", consisting of both a pointer to the object being mutated and a pointer to the cell within the object. In this case {{{#!hs data SomeType = SomeType { x :: {-# UNPACK #-} !(IORef Int) , y :: {-# UNPACK #-} !Char } getRef :: SomeType -> IORef Int getRef = x }}} `x (v :: SomeType)` would produce an object that contains a pointer to `v` (for the GC) and a pointer to field `x` of `v` (used to mutate `x`). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7662#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler