[Haskell-cafe] rewrite rules

[Sjoerd Visscher]

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 at w3future.com