[Haskell-cafe] More STUArray questions
mpercossi at martinpercossi.com
Sun Mar 12 16:00:22 EST 2006
On Sun, Mar 12, 2006 at 08:51:57PM +0000, Chris Kuklewicz wrote:
> There is a small error in the type of runSTMatrix, see below
> runSTMatrix :: (forall s. ST s (MMatrix s)) -> Matrix
> runSTMatrix a = runST ( do (MMatrix i j mblock) <- a
> block <- unsafeFreeze mblock
> return (Matrix i j block)
Hmm... now I get
Couldn't match the rigid variable `.' against `ST'
`.' is bound by the type signature for `runSTMatrix'
Expected type: ST s
Inferred type: . (forall s1)
In a 'do' expression: (MMatrix i j mblock) <- a
In the first argument of `runST', namely
(MMatrix i j mblock) <- a
block <- unsafeFreeze mblock
return (Matrix i j block))'
Couldn't match `ST s (MMatrix s)' against `MMatrix (forall s)'
Expected type: ST (forall s) (ST s (MMatrix s))
Inferred type: ST (forall s) (MMatrix (forall s))
In the first argument of `runSTMatrix', namely `runMatrix'
In the second argument of `($)', namely `runSTMatrix runMatrix'
Failed, modules loaded: none.
More information about the Haskell-Cafe