If you use the latest arc3.tar (unfortunately I haven't gotten around to merging these changes into the arc3.master branch on anarki), 'string will concatenate lists of strings (or indeed anything coercable to string) into one string, with no spaces, recursively:
arc> (string '("foo" bar (2 3) "baz")
"foobar23baz"
Also, 'rem is capable of removing characters from strings.
