NAME

       tailcall - Replace the current procedure with another command

SYNOPSIS

       tailcall command ?arg ...?
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DESCRIPTION

       The  tailcall  command  replaces the currently executing procedure, lambda application, or
       method with another command. The command, which will have arg ... passed as  arguments  if
       they  are  supplied,  will  be  looked  up  in  the  current namespace context, not in the
       caller's. Apart from that difference in resolution, it is equivalent to:

              return [uplevel 1 [list command ?arg ...?]]

       This command may not be invoked from within an uplevel into a procedure or inside a  catch
       inside a procedure or lambda.

EXAMPLE

       Compute the factorial of a number.

              proc factorial {n {accum 1}} {
                  if {$n < 2} {
                      return $accum
                  }
                  tailcall factorial [expr {$n - 1}] [expr {$accum * $n}]
              }

       Print the elements of a list with alternating lines having different indentations.

              proc printList {theList} {
                  if {[llength $theList]} {
                      puts "> [lindex $theList 0]"
                      tailcall printList2 [lrange $theList 1 end]
                  }
              }
              proc printList2 {theList} {
                  if {[llength $theList]} {
                      puts "< [lindex $theList 0]"
                      tailcall printList [lrange $theList 1 end]
                  }
              }

SEE ALSO

       apply(3tcl), proc(3tcl), uplevel(3tcl)

KEYWORDS

       call, recursion, tail recursion