Top-level bindings for unlifted types

[Neil Mitchell]

Hi,

The following program:

-------------------------------------------
{-# OPTIONS_GHC -fglasgow-exts #-}
module Test() where
import GHC.Base
test = realWorld#
-----------------------------------------

gives the error message:

    Top-level bindings for unlifted types aren't allowed:
        { test = realWorld# }

Changing to test _ = realWorld# works fine.

The question is why are these bindings disallowed? Reading the
"Unboxed values as first class citizens" paper I can't see it listed
as a restriction.

Thanks

Neil