[PLT announcement] PLT Scheme v4.1.5

From: Eli Barzilay (eli at barzilay.org)
Date: Sun Mar 22 01:04:29 EDT 2009

PLT Scheme version 4.1.5 is now available from


* Web Server:
  - new URL-based dispatching library `web-server/dispatch',
  - customizable continuation serialization policies for the stateless
    web language `web-server/stuffers',
  - abstraction of serve/servlet to build simpler dispatchers
  - HTTP Digest authentication support `web-server/http/digest-auth',
  - built-in cookie support in `web-server/http/cookie' and
  - highlighting and pretty-printing of errors in Xexpr constructions,
  - load control dispatcher for limit concurrent sessions

* Scribble:
  - Literate programming is now available using the new
    `scribble/lp' language.
  - A new `at-exp' language makes it convenient to use the
    scribble reader's @-expressions for general code.
  - The `scribble/text' preprocessor language has been extended to
    deal with indentation and other formatting issues.
  - The "scribble" command-line tool accepts a `--pdf' flag to
    render PDFs (via pdflatex).

* DrScheme now provides feedback when PLaneT downloads and
  installs new packages.

* Units & Contracts:
  - Elements of unit signatures can now be associated with
    contracts via the `contracted' signature form.
  - A contract combinator for units, `unit/c', has been added.
  - The new `with-contract' form provides a nestable submodule
    contract boundary, protecting a group of definitions from the
    surrounding code with contracts.
  - The `define/contract' form has been reworked and new define
    forms have been added: `define-struct/contract' and

* Language levels and teachpacks from the DeinProgramm project for
  the German textbook "Die Macht der Abstraktion" by Herbert
  Klaeren and Michael Sperber have been added.

* Misc:
  - Typed Scheme now comes with several more pre-wrapped
    libraries, found in the `typed' collection.
  - The `xml' and `html' collections are now contracted.
  - Binding parsing in net/cgi now interacts with `net/uri-codec's
    configuration parameters.
  - DrScheme captures logging output.
  - Check syntax: it is now possible to tack arrows crossing the
    currently selected text.
  - New `bitwise-bit-field' function.

* The usual pile of bugfixes.  (Notable: `scheme/package' works,
  `deflate' compression fixed, DrScheme language dialog issue
  resolved, `match' fixes, Windows networking, and much more.)

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

Feedback Welcome,
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!

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