posted by Eli Barzilay
PLT Scheme version 4.2.4 is now available from
scheme/fixnumlibraries 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.
scheme/unsafe/opslibrary 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/imagelibrary explicitly. For the full details, see the new Porting World Programs section of the documentation.
2htdp/imagelibrary 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.
scheme/classlibrary now provides
this%, which refers to the class of the current object (i.e.
scheme/generatorhas 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
$PLTADDONDIRenvironment variable or
-Acommand-line flags. This controls where downloaded Planet packages and their compiled Scribble documentation are installed.
- Additional extensions include: saving
errnoin foreign calls, much improved
sortspeed, normalized results from
procedure-arity, and more.