The state of the art for Arrow specs (clarifications and additions)

Brian Rice
Sun, 31 Oct 1999 12:58:10 -0800

At 12:59 PM 10/30/99 -0200, Jecel Assumpcao Jr wrote:
>I have attached a little picture of how I imagined Brain's first
>two statements. For those who can't deal with embedded GIF images,
>I am sorry, but it is only 2KB so shouldn't be too much of a bother.


>One thing that made it harder for me to follow Brian's explanations
>is that I always imagine arrows going from the CDR to the CAR, and
>not the way he did it. So the drawing helped me a lot - I made an
>arrow start from and end in the middle of another arrow in order
>to represent references. I didn't know who to represent "arrow is
>part of a graph", so I used different colors for that.

Yeah, that coloring idea works for annotations for very small examples.
When I have complicated (i.e. real-world) examples, only parts of the
example may be seen using the color notations.  For example, arrows will
most often be part of multiple graphs.  In cases like that, most likely the
best way to deal with it is to work with localized views of the system
(sort of like the ideas for replacing hierarchical browsers with a
web-based conceptual network browser where it's easiest to work with a
local set of connections that changes with the focus).

>You can see that my lack of comments is just pure ignorance (and
>a lack of time to fix that).
>BTW, I now have Squeak 2.6 running in my system (almost - I can't
>make the network name resolutions system work so I have to access
>everything by its IP address) so it would be interesting for me
>to try the Arrows prototype. Where is it? I couldn't find it from
>the Tunes home page...
>-- Jecel

The really rudimentary code is at

I'm going to attempt to manipulate the objects of these classes via an
existing Lisp interpreter for Squeak, basically by crippling the parser and
working from there on the evaluator.