[Haskell-cafe] Where is SNMap for stable names?

There is an abstract type called SNMap for stable names referred to in [1]. This has apparently disappeared from GHC a long time ago. Is it still available somewhere, or is there a suitable replacement for it? Regards, Sean [1] "Stretching the storage manager: weak pointers and stable names in Haskell" - http://research.microsoft.com/apps/pubs/default.aspx?id=67497