TCL is a better Scheme

This is a tail-recursive naive implementation of factorial for TCL 8.6:
proc fac-tr {n {k 1}} {
if {$n <= 1} {
return $k
} else {
tailcall fac-tr [- $n 1] [* $n $k]
}
}

>>12
Manipulating an AST with what is basically a regexp preprocessing hack doesn't help me when I just want to load a file format or write data for a protocol. How would a macro help me decode a PNG, for example? This attitude that the only things worth having are in Lisp is why Lisp does nothing useful.