[Haskell-beginners] what does (# a, s #) mean?

[Amitava Shee]

I came across this definition in ghc source

$GHC/compiler/utils/State.hs
=======================
newtype State s a = State { runState' :: s -> (# a, s #) }


What does the construct (# a, s #) mean?

Thanks & Regards,
Amitava Shee
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/beginners/attachments/20110410/e2d175a6/attachment.htm>