Recursive factorial - continuation passing style

proc fact3 {n c} {
    if {$n == 0} {
	{*}$c 1
    } else {
	tailcall fact3 [- $n 1] \
	    [list apply {{n c f} {
		puts [list continuation $c will get the product of $n and $f]
		{*}$c [* $n $f]
	    }} $n $c]
    }
}
fact3 6 puts