[Uk-lispers] Scheme UK Meeting: 11 August 2004: Bring out yer dead! A Transputer interpreter in two acts

Noel Welsh noelwelsh at yahoo.com
Tue Jul 20 09:16:57 PDT 2004

          Scheme UK Meeting: 11 August 2004

The next meeting of the Scheme UK user's group will be
held on Wednesday, 11 August 2004 from 7pm till we leave
for the pub.  The meeting will take place at the offices
of LShift (see http://www.lshift.net/contact.html for
directions).  This meeting will be held in conjuction with
UK Lispers.

Bring out yer dead! A Transputer interpreter in two acts
By Matt Jadud

ACT I: Scheme

occam is a small (dead?) language based on an the
Concurrent Sequential Processes algebra[1]. Scheme is a
small (not so dead?) language based on the lambda
calculus[2]. However, Scheme is the All Language,
descended from the Mighty LISP, blessed by Guy
Steele. What better language to write an interpreter of
Transputer bytecode (the compiled form of occam programs)
than Scheme?


Unfortunately, while semantically clear, a Scheme
interpreter runneth not on the LEGO Mindstorms. So, the
Scheme interpreter was rewritten, largely line-for-line,
in C, and it became many times faster and many times
smaller.  What we ended up with is a small, portable
runtime for occam programs, that currently runs on
Linux/x86, Linux/MIPS, Windows, Mac OSX, and the LEGO

This play will present a bit of background on occam (for
those who are unfamiliar), the interpreter itself, and
most importantly, some bits about why we think it is a
good thing that we can now run occam on the LEGO
Mindstorms.  If FedEx is willing, little robots will be

(For those following along at home, the first paper found
at reference number three is probably the most interesting
for you to glance at, if you wish, before the talk.)

[1] http://archive.comlab.ox.ac.uk/csp.html
[2] Oh, please. You guys know where to find Scheme stuff
    on the WWW.
[4] Although not mentioned previously, you may also be
    interested in the "Little Languages for Little Robots"
    paper on the same page as reference #3; it is, in some
    backwards way, related.

Email: noelwelsh <at> yahoo <dot> com
Jabber: noelw <at> jabber <dot> org

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