PLT Scheme v4.2.2

PLT Scheme version 4.2.2 is now available from

http://plt-scheme.org/

* DrScheme now, by default, compiles all of the files that are
loaded when it runs a program and saves the compiled files in the
filesystem. This should lead to faster load times (not faster
runtimes) since it avoids re-compiling files whose dependencies
have not changed.

* New Scribble libraries and documentation make it easier to get
started with Scribble, especially for uses other than PLT
documentation. DrScheme now has better indentation and syntax
coloring support for Scribble languages (and generally all @-exp
based languages).

* The new `syntax/keyword' library provides support for macros with
keyword options. A new quick start guide has been added to the
documentation for the `syntax/parse' library.

* Added support for abstract contracts via the #:exists keywords.
This is an experiment to add support for data hiding to the
contract system.

* Added `in-producer': a sequence expression makes it easy to
iterate over producer functions (e.g., `read'). A new
`scheme/generator' library creates generators that can use a
(parameterized) yield function.

* HtDP langs: several primitives now consume 0 and 1 arguments in
ISL (and up), including `append', `+' and `*'. In addition,
`make-list' was added to the primitives.

* The API to Universe has a number of new constructs. All Universe
programs should run unchanged. The most important change is the
addition of `animate' as an alternative name for `run-simulation'.
In addition, adding the clause `(state true)' to a world
description now pretty-prints the state of the world into a
separate canvas.

* A number of changes were made to the DeinProgramm / DMdA language
levels: The `check-property' and `contract' forms were added,
`define-record-procedures-parametric' has changed. See the
documentation for details.

* The test engine in the HtDP languages no longer warns programmers
when the Definitions window has no tests.

* ProfessorJ (and related code) is no longer included in the PLT
distributions. It may re-appear in the future as a PLaneT package.

[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!

##########################################################################
# Send submissions for comp.os.linux.announce to: cola DeleteThis @stump.algebra.com #
# PLEASE remember a short description of the software and the LOCATION. #
# This group is archived at http://stump.algebra.com/~cola/ #
##########################################################################