.SH NAME
lab 31 - accumulator generator in limbo--and beyond
.SH DESCRIPTION
In lab 25 I tried to tackle the problem of writing an accumulator
generator in the languages available on inferno. I blithely 
assumed it wasn't possible in Inferno. I'm happy
to say I was wrong. Rog emailed me the answers, so
I'm just reporting what he gave me. But it was very
enlightening, a big Aha!, and made me view limbo in a different
way.
.PP
funny thing is, it *is* possible in limbo, if you take a somewhat
more liberal definition of the term "function".
recall that a limbo channel can act like a function:
e.g.
       c: chan of (int, chan of string);
can represent a function that takes an int and returns a string
(through the reply channel).

       c <-= (99, reply := chan of string);
       sys->print("result is %s\n", <-reply);

i've attached a Limbo version of the accumulator-generator that uses
this kind of thing.  i'll leave it to you to decide if this fulfils
Greenspun's rule or not!

> It doesn't strictly pass the test because you are passing an integer
> not a number.

ahhh but it can if i want it to!
(i really like inferno's parametric types...  note the accgen and acc
functions could be in an external module).

.PP
I had to go back and read Doug Mcilroy's
Squinting the Power Series. I ported the code writing in newsqueak
to inferno, to absorb the lessons from this. Studying the paper and the code
is well worth it.
.PP
Where from here?
I tried to apply what I'd learned. I created a tool
for querying a little database. The query is made 
by chaining processes in a similar manner as the power series
code. I'll be posting this code at a later time, as I hope to incorporate
it into the folkonomy fs.

.SH SEE ALSO
Communicating Sequential Proccesses
Squinting the Power Series
.SH FILES.