While most of these helper functions seem pretty sane, I can't help but think that the delete function really ought to be written in C for speed and correctness (following the pseudo code example at http://docs.info.apple.com/article.html?artnum=107884).   The Tcl function I see below is not going to be particularly fast on either broad or deep hierarchies of files, and mass deletions of stuff in cleanup procedures is fairly common place.  I think the other functions are low-overhead enough that Tcl is a fine implementation language, but not delete.