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From: Eli Barzilay on 28 Jan 2010 21:56
PLT Scheme version 4.2.4 is now available from

http://plt-scheme.org/

* 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.

* `2htdp/universe': We have severed the connection between universe
and an image library and made a few other, minor changes. Most
programs will now have to change to require the `htdp/image'
library explicitly. For the full details, see the new Porting
World Programs section of the documentation:
http://docs.plt-scheme.org/teachpack/2htdphtdp-port.html

* The `2htdp/image' library continues to grow. In this release, it
is supported by `2htdp/universe', equality changed to be based on
how the images are drawn, cropping and curves were added, and
support for more kinds of pens were added.

* `htdp/world': The old world teachpack remains deprecated. HtDP/2e
exclusively uses the new 2htdp/universe library. For backwards
compatibility, the world teachpack will remain in the distribution
until the coming summer.

* The `scheme/class' library now provides `this%', which refers to
the class of the current object (i.e. `this').

* `scheme/generator' has convenient functions for infinite
generators, and for converting a generator to a sequence for
iteration.

* PLT Scheme's add-on directory can be customized by the
$PLTADDONDIR environment variable or `--addon'/`-A' command-line
flags. This controls where downloaded Planet packages and their
compiled Scribble documentation are installed.

* Additional extensions include: saving `errno' in foreign calls,
much improved `sort' speed, normalized results from
`procedure-arity', and more.

[Note that mirror sites can take a while to catch up with the new
downloads.]

Feedback Welcome,
--
((lambda (x) (x x)) (lambda (x) (x x))) Eli Barzilay:
http://barzilay.org/ Maze is Life!
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Prev: [deadline extension] 3rd European Lisp Symposium (ELS 2010)
Next: Evaluating/compiling forms in the current lexical environment.