Not 100% sure (especially without source/core), but my guess is that the higher-rank types make the rule unlikely to fire. Try -ddump-simpl to see the core output, and look for places where you expect the rule to fire. I suspect you will find that the types of f and g are not "forall" at that point in the code, but have already been specialized. Is there a reason you cannot use this simpler rule? {-# RULES "transform/tranform" forall f g l. transform f (transform g l) = transform (g.f) l #-} -- ryan On Mon, Jun 22, 2009 at 2:41 AM, Sjoerd Visscher<sjoerd@w3future.com> wrote:
Hi all,
I have a rewrite rule as follows:
{-# RULES "transform/transform" forall (f::forall m. Monoid m => (a -> m) -> (b -> m)) (g::forall m. Monoid m => (b -> m) -> (c -> m)) (l::FMList c). transform f (transform g l) = transform (g.f) l #-}
It fires on this code:
print $ transform (. (*2)) (transform (. (+1)) (upto 10))
But it doesn't fire on this code:
print $ map (*2) (map (+1) (upto 10)))
with
map g x = transform (. g) x
and with or without {-# INLINE map #-}.
What am I doing wrong?
-- Sjoerd Visscher sjoerd@w3future.com
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe