PLT Scheme version 4.1.4 is now available from

  • New libraries include `scheme/package' (for nestable static modules) and `ffi/objc' (support for Objective-C).
  • New teaching support includes a "universe.ss" teachpack for connecting "worlds" over a network.
  • Redex now supports automatic test-case generation. Specify a predicate that should hold of your reduction system, and Redex will attempt to falsify it. See 'redex-check' in the manual for more details.
  • Improvements to the run-time system include better and more reliable memory-limit tracking, function contracts that preserve tail recursion in many cases, native debugging backtraces on x86_64, and performance improvements.
  • Improved libraries include enhancements to `scheme/sandbox', better handling of zero-sized matches by `regexp-split' and friends, an `equal<%>' interface for specifying equality on class instances (and more general support for attaching properties to interfaces), equality (via `equal<%>') for image objects, and refinements to `scheme/foreign' to support atomic operations and function-pointer conversions.
[Note that mirror sites can take a while to catch up with the new downloads.] Feedback Welcome.


Madoka said...


Let me notify you that the current version of MzScheme does not start on my old win98 machine.

I've been using 4.1.1. for some time and it's been working all fine. To my dismay, however, when I tried to run the newly installed one, it just caused crash and I had to reboot the PC. The same thing happned with mzc.exe, too.

I can't figure out where the problem is, but I hope it will be solved anyway. (Or will the support of win95 family be discontinued?)

Bob said...

Win95 family should be discontinued. End of story.

Jesus Boadas said...

Greetings Fellows.

Im getting this error on XP/OSX in about DrScheme -> our software license

procedure send-main-page: expects 0 arguments plus optional arguments with keywords #:fragment, #:notify, #:query, and #:sub, given 1: "license/index.html"

=== context ===
/Applications/PLTScheme/collects/scheme/private/more-scheme.ss:155:2: call-with-break-parameterization
/Applications/PLTScheme/collects/scheme/private/more-scheme.ss:271:2: call-with-exception-handler

Best Regards

Eli Barzilay said...

The "software license" problem is fixed for the next version. As for the Windows98 problem, we still didn't find what the problem is...

Matthew Flatt said...

Madoka: thanks for letting us know. We have restored pre-XP compatibility for the next version. If you'd like to try the snapshot, see http://pre.plt-scheme.org/installers/