Annotation for unfolding wanted

[Duncan Coutts]

On Tue, 2007-07-31 at 10:36 -0400, Jan-Willem Maessen wrote:

> I think what's meant here is translating something like this:
> 
> {-# INLINE f #-}
> f x y z = ...  f x' y' z' ...
> 
> into this:
> 
> {-# INLINE f #-}
> f x y z = f' x y z
>    where f' x y z = ... f' x' y' z' ...
> 
> That is, shoving (all of) the recursion in a level.  Then inlining f  
> results in a fresh loop, which presumably can be specialized or  
> optimized in various ways.

This transformation is critical for performance of foldr and foldl(').
The versions in GHC's libraries are manually written in the latter
style.

Duncan