[plt-dev] Release Announcement for v4.2.4

At Sun, 24 Jan 2010 19:26:09 -0500, Eli Barzilay wrote:
> * [Matthew] scheme/fixnum, scheme/flonum, flvectors
> 
> * [Matthew] Unsafe stuff (make it's ready to describe now?)


 * The `scheme/flonum' and `scheme/fixnum' libraries provide flonum-
   and fixnum-specific operations. In the case of flonum-specific
   operations, the JIT compiler can recognize combinations of
   operations (including local bindings) and improve performance by
   "unboxing" intermediate results.

 * The `scheme/unsafe/ops' library provides arithmetic and other
   operations that are implemented without dynamic checks. Avoiding
   checks can sometimes improve performance, but at the expense of
   safety.


> * [Matthew/Eli] `#:save-errno'?

Too minor for the announcement, I think.