Below is the third (and hopefully final) draft of the release
announcement items for v5.2.1. Last call for comments.
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* Performance improvements include the use of epoll()/kqueue()
instead of select() for the Racket thread scheduler,
cross-module inlining of small functions, and the use of SSE
instead of x87 for JIT-compiled floating-point operations on
platforms where SSE is always available (including x86_64
platforms). A related change is the interning of literal
numbers, strings, byte strings, characters, and regexps that
appear in code and syntax objects.
* DrRacket uses a set of composable ray-traced icons available
from the new `images' library collection.
* Typed Racket's `typecheck-fail' form allows macro creators to
customize the error messages that Typed Racket produces. This
is especially useful when creating pattern matching macros.
* The performance of Redex's matcher has been substantially
improved; depending on the model you should see improvements
between 2x and 50x in the time it takes to reduce terms.
* Plots look nicer and are more correct at very small and very
large scales. New features include customizable dual axis ticks
and transforms (e.g. log axes, date and currency ticks, axis
interval collapse and stretch), stacked histograms, and 3D
vector fields. The legacy `fit' function and libfit have been
removed.
* The `2htdp/universe' library's `big-bang' form supports an
experimental game pad key handler.
(edu: The handler accepts a limited number of keys, similar to a
game pad; the addition of a game-pad handler also overlays the
attached game pad icon on the big-bang canvas. A compatible
addition will appear in WeScheme.)
* The `db' library now supports nested transactions and PostgreSQL
arrays. Bugs involving MySQL authentication and memory corruption
in the SQLite bindings have been fixed.
* The Macro Stepper tool in DrRacket no longer executes a program
after expanding it.
* In the DMdA teaching languages, infinite recursive signatures
("streams", for example) with no intervening `mixed' are now
supported, and the signatures of record definitions without fields
now have generators for use with `property'.
* MysterX's ActiveX support is deprecated and will be removed in
the next release. MysterX's core COM functionality will become
deprecated in the next release, but COM functionality will be
supported for the foreseeable future as a compatibility layer
over a forthcoming `ffi/com' library.
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