Christopher J. Vogt
Wed, 25 Mar 1998 11:04:10 -0600
At 9:29 PM -0600 3/24/98, J. Han wrote:
>To Old Timers:
>I have been meaning to ask this question and present discussion
>seems to be a good place to ask it:
> What is it like using a Lisp Machine?
What facilities does an OS provide? File system, memory management, I/O,
process management, etc. Now, imagine all of those facilities written in
Lisp, running in a single address space. Don't like the file system?
Write a new one. Feel the file system is missing a particular feature
(like file versions maybe?) modify it to support it. Want to change the
schedule, go ahead. Have some ideas about memory management, gc, etc?
Code them up and try them out. You have a fully open and integrated
environment. There is nothing that is off limits, no super user, no
protected mode, etc.
You don't need to learn a command line language, or a scripting language,
because Lisp is all those things, and more. Your one programming language
does what multiple languages currently do. The power and flexibility of
this makes progamming life much easier and more enjoyable. I haven't
enjoyed programming since I last used a Lispm.
A side affect of all this is that you virtually never have a crash. No
system freeze, no blue screen of death, no core dump. Most people ran
their Lispm until it ran out of virtual memory space, which in my case was
between once a week and once a month. With todays gigabyte disks, I could
run for months without booting.
The debugger had features that I still don't see. You could set a
breakpoint in function foo, to only be triggered if foo was called from
bar. You could monitor a variable and break only if the variable was read
(or written, or bound, or unbound, or any combination of the above).
Incredibly powerful debugger.
Ever use a program and wonder how they coded it? On a lispm you could just
"break" the program and poke around. If it was system software, the
sources were included and you could m-. (edit definition) from the debugger
and be in the editor looking at the source code.
The System Constrcution Tool (SCT) was like defsystem on steroids. I still
miss the patching facility. m-x Add Patch and friends (Add Changed
I hope this gives you a flavor of what a Lispm has that other systems
don't, and why it is valuable, and why us "old farts" wax nostalgic.
Christopher (Chris) J. Vogt