Anyway, I don't see it anywhere in the release notes, but I get the vibe that type families are supposed to be "fully working" now. Is that correct? If so, why no mention anywhere?
Type families have been completely reimplemented and should be stable now, but there are some bugs - notably equality constraints in superclasses are not supported in GHC 6.10.1, i.e.
class (F a ~ b) => C a b where type F a
As indicated by this bug report: http://hackage.haskell.org/trac/ghc/ticket/2715 And here: http://haskell.org/haskellwiki/GHC/Indexed_types#Equality_constraints
Also, the release notes tantelisingly hint that the long-awaited parallel-array stuff is finally working in this release, but I can't find any actual description of how to use it. All the DPH stuff seems on the wiki was last updated many months ago. You would have thought that such a big deal would be well-documented. It must have taken enough effort to get it to work! You'd think somebody would want to shout about it...
I put up a DPH version of the binarytrees benchmark in the shootout: http://haskell.org/haskellwiki/Shootout/Parallel/BinaryTreesDPH There are some notes there; the only documentation I really used was the documentation built by the GHC build process on the 'dph-*' libraries (you can see them in 6.10 by just doing 'ghc-pkg list' and looking through it.) I was thinking of porting more of the parallel shootout entries to use DPH, but I'm busy right now - results could be interesting. Austin