Note that you don't technically need to install git since github can generate tarballs for you. (http://github.com/nex3/arc/tarball/master for the master branch, http://github.com/nex3/arc/tarball/stable for stable.) (Maybe this would be a good thing to put on kens's downloading Anarki guide.)
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Original arclangauage thread: http://arclanguage.org/item?id=5014