[nightly] 22-Sep-2010 build of HEAD on i386-unknown-linux (cam-02-unx)

[Simon Peyton-Jones]

| fits into a float. I was doing this before basically be having
| something like ((realToFrac :: Double -> Float) . (realToFrac :: Float
| -> Double)). Recently GHC seems to have learned to optimise this by
| removing that code completely. (Before if I told GHC not to inline
| some stuff this stopped it doing that, but not anymore it seems).

I'm agnostic about whether optimising realToFrac . realToFrac to the identity is OK (though I'd have thought so), but I don't think I see how it happens!   Maybe a RULE? But I don't see one.  If you can show it happening that'd be interesting.

Simon