[plt-scheme] [ANN] Heist 0.2.0, now with full list support

From: James Coglan (jcoglan at googlemail.com)
Date: Thu Apr 2 14:45:50 EDT 2009

Hi all,

I just released the 0.2.0 version of Heist, my Ruby Scheme runtime. Changes
in this release include:

* Entirely revised to correctly support lists as linked pairs
* Complete set of R5RS list functions
* Syntax for dotted pairs and improper lists implemented
* Rest-args for functions using dot notation
* Almost-complete R5RS numeric library, including complexes and rationals
* Some parser bugs regarding literals and quoting fixed
* Many macro parsing and expansion bugs fixed, esp. concerning nested
repeating patterns
* Macro keywords and collisions with local variables now follow the spec
* R6RS ellipsis escaping feature -- (... ...) -- implemented
* All library syntax now implemented as macros, should all support call/cc
* Ruby data can now be executed as Scheme code
* Lots of inline documentation for the runtime

More information on GitHub and my blog:


Of particular interest to me is the Ruby-data-as-Scheme-code feature, for

scheme = Heist::Runtime.new

scheme.exec [:define, [:square, :x],
              [:*, :x, :x]]

scheme.exec [:square, 9]
#=> 81

Once I've settled on a nice way to expose the macro system to Ruby, this
could be used with ParseTree to rewrite Ruby code, like raganwald's
'rewrite' gem. Also, there's a possibility for someone to write a new Ruby
interpreter by taking ParseTree and adding a new set of built-in functions
to the Heist runtime to execute its output. If someone has a serious stab at
this I'd love to see the results.

James Coglan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.racket-lang.org/users/archive/attachments/20090402/7e3a41ec/attachment.html>

Posted on the users mailing list.