Hello Bulat,
Tuesday, March 7, 2006, 2:57:47 PM, you wrote:
BZ> The following code compiles with GHC but not with Hugs. moreover, if
BZ> you replace STURef with STRef in instance definition, all will be
BZ> fine. bug?
i found the answer himself. Hugs just can't properly understand kind
of STURef in this case. "type STURef = STRef" should be changed to
"type STURef s a = STRef s a". btw, there was also another cases where Hugs
can't determine kind of identifier from such "partial type declarations"
... after checking my solution: Hugs also don't allow to use type
synonym here, so i should change this declaration to
"newtype STURef s a = STURef (STRef s a)". at least this work....
BZ> {-# OPTIONS_GHC -cpp -fglasgow-exts #-}
BZ> import Control.Monad.ST
BZ> import Data.STRef
BZ> --
BZ>
-----------------------------------------------------------------------------
BZ> -- Unboxed references in ST monad
BZ> type STURef = STRef
BZ> -- | Create new unboxed reference in ST monad
BZ> newSTURef :: e -> ST s (STURef s e)
BZ> newSTURef = newSTRef
BZ> --
BZ>
-----------------------------------------------------------------------------
BZ> -- Monad-neutral interface for fast unboxed references
BZ> class (Monad m) => URef m r | m->r, r->m where
BZ> newURef :: a -> m (r a)
BZ> instance URef (ST s) (STURef s) where
BZ> newURef = newSTURef
BZ> --
BZ>
-----------------------------------------------------------------------------
BZ> -- Main
BZ> test = runST ( do newURef (0::Int)
BZ> return '1'
BZ> )
BZ>
--
Best regards,
Bulat mailto:[EMAIL PROTECTED]
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