On 17 January 2013 21:54, David Barbour <dmbarbour_at_gmail.com> wrote:
> It is wonderful to know other people feel that way. Even putting aside live
> performance, there are many social and HCI aspects to PL design that are not
> widely acknowledged by the PL communities.
Yes absolutely. People don't necessarily enjoy finding out that they
don't know very much at all about something they thought they had
pretty much covered. Even the subtitle of your blog "thoughts on
programming experience design" might make some in the PL community
physically angry. What, programmers are supposed to have *experiences*
now?
> A useful feature for live programming is an ability to reason about a
> program's behavior in terms of its code and environment - in particular,
> while remaining ignorant of the *history* of that code and the *history* of
> that environment (except insofar as the history is explicitly recorded in
> the environment). A consequence is a nice stability property: that
> restarting the system does not have any semantic impact on its behavior.
That's a big "except insofar" though. Restarting a system does have
(cognitive) semantic impact by not running for a while. For example, a
restarted batch program takes longer to run to completion, and if it
was a programming for beeping, it will have stopped beeping for a
period of time.
Also, you can't really reason about a program's behaviour if someone
can come along and change it while you're trying to reason about it.
Live code is the ultimate in mutable local state, isn't it? :)
I guess my point is, I think that the computer scientist's habit of
ignoring the existence of both time and human interaction in the
execution of algorithms doesn't work at all if an algorithm can be
changed while it is running. You can contain purity inside monads, but
introducing liveness makes it all impure again, doesn't it? Changes to
a program are part of it, and absolutely nothing is certain or
immutable, except the fact that everything halts eventually.
alex
Received on Thu Jan 17 2013 - 22:36:47 GMT