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PLT Scheme v200 available
[The following announcement may be of interest to subscribers of the LL1
PLT Scheme v200 is now available from
We urge all users to upgrade to this new, stable release.
The new release dramatically improves previous releases in many ways.
The improvements include:
- The PLT Scheme language includes a module system that properly
integrates macros and modules. The macro module system enables
programmers to write different modules of a product in different
languages, yet preserves the ability to compile modules separately.
For details, see
Matthew Flatt. Composable and Compilable Macros: You want it when?
ICFP 2002. To appear. See http://www.cs.utah.edu/plt/publications/
The implementation of PLT Scheme is based on the new module system.
The framework also provides constructs for attaching assertions to
exported values of a module. See "contracts" in Help Desk. For
on the underlying concepts, see
Findler, Felleisen. Contracts for Higher-Order Functions.
ICFP 2002. To appear. See http://www.ccs.neu.edu/scheme/pubs/
- DrScheme now provides a fully-compliant R5RS language, including
- DrScheme includes a graphical module browser.
- New languages can be added to DrScheme easily. See the Tools manual
details. An example, Algol 60, is available from our contributions
- The teachpack implementation interface has changed because teachpacks
now add new syntax to a language level. The user interface of the
existing "How to Design Programs" (HtDP) teachpacks remains the same.
- A new collection, parser-tools, supports the generation of lexers and
parsers for LALR(1) grammars. Unlike conventional lex and yacc
implementations, the PLT variants support the specification of
and related code in a single file. The embedding of Algol 60
demonstrates this point and also shows how source information is
propagated through the elaboration and interpretation process.
- Programmers can now mix XML syntax and Scheme syntax in the
window via embedded editors (see the "Special" menu).
- PLT Scheme now includes a Web server that offers special support for
interactive servlets. DrScheme supports the development of such
in the conventional incremental manner; use the servlet.ss teachpack
the HtDP teachpack. A "Create servlet" mechanism, analogous to the
"Create executable" mechanism, is forthcoming.
- DrScheme supports a tool for profiling code.
- DrScheme's Definitions and Interactions windows are re-sizable.
- In addition to English, DrScheme's GUI interface supports Danish,
French, and Spanish. A partial version of German is also available.
Improvements and additional languages are welcome contributions.
- The documentation includes the on-line book:
Dorai Sitaram. "Teach Youself Scheme in Fixnum Days". 2000-2002.
- v200 includes the tex2page TeX-to-HTML converter. It was used
to produce the on-line versions of SICP and HtDP and our own
- An online version checker makes sure the installed versions
of DrScheme and other packages are up-to-date.
DrScheme v200 is available for
+ Windows (95/98/Me/NT/2000/XP)
+ Mac OS X
+ Linux (tar.gz and RPM formats)
+ Sparc Solaris 8
* Other Unix (source code)
Source code is easily compilable on most other Unix platforms.
- PLT Scheme v200 is not yet available for the Mac OS Classic
- A follow-on release, v201, with additional improvements, is expected
late this summer.
The PLT Scheme crew thanks its many users for their invaluable
feedback, especially the users who braved our alpha releases in