Tcl has been a testbed for safe interpretation since before Java existed (at least under that name). As security becomes ever more important, perhaps attention will return to Tcl just for this feature.
Recognize, first, its uniqueness. Nominally peer languages--Perl, PHP, Python, Ruby, and others--have security features, but none of them really boast the power and flexibility of interps [explain].
Is this realy true? I'm using safe interps all the days with great success for import/export filters - so there is no file type it cannot read/create :-) One thing more to stay with Tcl ...