
New Arc Out - rams
http://arclanguage.org/install
======
jrockway
Perhaps more interesting is that mzscheme changed a core language feature
(mutable cons cells) without providing any backcompat.

~~~
Tichy
So is MzScheme effectively like Erlang now? I thought the immutable memory in
Erlang does make some things difficult to code, which would have been a reason
for me to prefer Scheme.

~~~
by
I doubt you would find the immutable aspect in Erlang a problem in practice. I
don't know MzScheme, but Erlang has a its own very different philosophy. I
suggest Joe's thesis as an interesting read.

<http://www.sics.se/~joe/thesis/armstrong_thesis_2003.pdf>

~~~
Tichy
Well I found it a problem when I tried to program a Sieve Of Eratosthenes for
project Euler. Also when I considered a grid based alife simulation. I guess
the only way would be to use a process per cell?

~~~
by
Sometimes the mutable structures get passed around in the function arguments,
so you might do a sequence of tail recursive calls and on each call you pass
in the next board state to the same function. I would hope the Erlang
Questions mailing list would help you if you posted a small example and
explained your troubles to them. There are lots of very clever Erlang people
there.

<http://www.erlang.org/faq.html>

~~~
Tichy
Might try it again - not that I didn't enjoy it, it was fun.

------
torr
Just curious: Why was mzscheme chosen to implement Arc rather than some other
Scheme implementation?

~~~
pg
Originally we used Scheme48. I forget exactly why we switched. I vaguely
recall some problem with threads. I think we chose PLT Scheme because it
seemed like the default Scheme implementation.

------
khandekars
In case you decide to compile MzScheme 372 from sources on a Fedora 10 box
that has SELinux in enforcing mode, you need to take a few (simple) additional
steps:

[http://aadnyavali.wordpress.com/2009/06/07/making-
arc-3-play...](http://aadnyavali.wordpress.com/2009/06/07/making-arc-3-play-
nicely-with-selinux-on-fedora-10/)

I'm still downloading Fedora 11, but suspect that the same exercise will be
needed for that as well.

------
s-phi-nl
I wonder whether Arc will end up in effect maintaining mutable-cons mzscheme.
If this happens, I hope that Arc's focus won't shift to the implementation
details.

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astine
I wonder if PG can tell us what the new changes are. I'm sure that there is a
changelist, but I don't see it.

~~~
kylec
Actually, pg has said he hasn't kept track of the changes:

<http://arclanguage.org/item?id=9399>

Fortunately, someone else has taken the time to analyze the differences
between arc2 and arc3:

<http://arcfn.com/2009/06/whats-new-in-arc3.html>

~~~
pg
There were also a couple changes since then. IIRC the most significant are
that ontable is gone (each expanded to take its place) and that you can call
readc etc with no arg (and read from stdin).

