Installing the Arc language on Mac OS X is trivial, assuming you have the right version of MzScheme.

Install MzScheme 352 with MacPorts

Arc requires MzScheme, version 352. The install instructions warn: “Don’t use the latest version. There is said to be some bug/feature in it that breaks Arc.” The version of mzscheme in MacPorts is 371, so we have to tweak the portfile, and the only historical versions of mzscheme I can find portfiles for are 201 and 360. There seem to have been some major build changes between 352 and 360, so I frankensteined the portfile for version 201. You can find my version here. I’m running 10.4.11 on my dev machine, and I haven’t tested anything else.

Thanks go to bitshaker.com for the instructions on setting up a local port repo.

1. mkdir /Users/Shared/dports/lang/mzscheme
2. Edit /opt/local/etc/macports/sources.conf to look like this:

   # To enable your local ports repository, uncomment and customize the
   # following line to point at your local dports directory
   # Example: file:///Users/landonf/misc/macports/dports
   #
   # To get macports from the macports rsync server use:
   # rsync://rsync.macports.org/release/ports/
   file:///Users/Shared/dports
   rsync://rsync.macports.org/release/ports/
     

3. Download this portfile and copy it to /Users/Shared/dports/lang/mzscheme/Portfile
4. Update the ports index:

   portindex /Users/Shared/dports

5. When you run port list mzscheme, you should have an entry for mzscheme @352
6. Install with:

   sudo port install mzscheme @352

7. Is mzscheme the right version? Does it run?

   $ mzscheme
   Welcome to MzScheme version 352, Copyright (c) 2004-2006 PLT Scheme Inc.
   > (+ 1 2 )
   3
   (exit)
   $
     

Download Arc and run it with mzscheme

Download http://ycombinator.com/arc/arc0.tar and untar it somewhere useful on your system. ~/src/ perhaps?

$ tar -xv arc0.tar
$ cd arc0
$ mzscheme -m -f as.scm 
Use (quit) to quit, (tl) to return here after an interrupt.
arc> (+ 1 2)
3
arc> (quit)

http://arclanguage.org/install