On Tue, Sep 28, 2010 at 10:10 PM, David Fox <[email protected]> wrote: > I'm seeing errors like this in various places, which I guess are > coming from the new type checker: > > Data/Array/Vector/Prim/BUArr.hs:663:3: > Couldn't match type `s' with `s3' > because this skolem type variable would escape: `s3' > This skolem is bound by the polymorphic type `forall s. ST s a' > The following variables have types that mention s > fill0 :: MBUArr s e -> ST s Int > (bound at Data/Array/Vector/Prim/BUArr.hs:669:5) > In the first argument of `runST', namely > `(do { marr <- newMBU n; > n' <- fill0 marr; > unsafeFreezeMBU marr n' })' >
GHC no longer generalizes local bindings - which means that while previously the 'where' defined function would have had a type: > fill0 :: forall s . ... -> ST s Int Where the elipsis indicates an unspecified portion of the local type signature. I would recommend writing a type signature, but that requires writing a type signature for it's helper function: > fill s i = ... Except I don't know how to write a type signature for this. The value 's' passed in is bound by pattern matching on this guy's constructor: data Stream a = forall s. Stream (s -> Step s a) !s Int in the top-level function, so I don't even know if it has a type I can name. I'll try to boil this down to something I can put on hpaste. Antoine _______________________________________________ Glasgow-haskell-users mailing list [email protected] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
