Richard Suchenwirth 2005-04-08 - What happens when a proc calls itself. Popular in functional programming. In Tcl, we're a bit handicapped by the [interp recursionlimit] which is at ~398 on Windows, even if set higher.
Here's an example for a recursive integer range generator, so that [iota1 5] == {1 2 3 4 5} :
proc iota1 n {expr {$n == 1? 1: [concat [iota1 [- $n 1]] $n]}}rdt For completeness, shouldn't your definition of - (from http://wiki.tcl.tk/11389 ) be here also? - RS: Oops, of course - just another one-liner :)
proc - {a {b ""}} {expr {$b eq ""? -$a: $a-$b}}To illustrate the recursionlimit problem (which is directly related to the C stack):
% interp recursionlimit {} 10000
10000
% proc Llength list {expr {$list eq ""? 0: 1+ [Llength [lrange $list 1 end]]}}
% Llength [iota1 398]
398
% Llength [iota1 399]
too many nested evaluations (infinite loop?)Of course it's silly to reimplement llength this wasteful way, as Tcl' lists first and foremost know how long they are - but in Lisp, this implementation might make more sense :)