🚀 go-pugleaf

> (Hume Smith)

>  has anyone tried adding socket functions to xlisp?  any ideas how to
> make it sort-of pretty, unlike the C underneath?

 I added socket based communications to PC-LISP for our CAD tools
on SUN/RS/APOLLO and HP workstations. Similar things could easily be 
done with XLisp.

 We created a (socketopen <addr> <port> [<timeout>] function.
If provided, the <timeout> indicated an active connection, if
absent the connection was passive. The function simply returned
a normal file descriptor which could be (read) etc. using the
normal I/O functions. This meant that S-expressions could be
sent through the sockets and read on the other side. We used the
TCP_STREAM protocol and modified the (read)/(print) functions
to keep track of the last I/O direction used and to rewind(fd) if
the direction changed. With this done, the normal I/O functions
were used for socket based communications and the socketopen
function was used to open the connection.

 We even set up asynchronous socketopen/read/eval/print loops
at the top of some of our CAD tools so that the tool could
asynchronously receive a LISP S-expression, evaluate it, and
print the result back to the sender. Beats the heck out of
formatting packets and you get not only data exchange but
control exchange too!

 Peter Ashwood-Smith.