Version 3 of join

Join converts a Tcl list into a string. It glues together the elements of a list using a supplied character as element seperator. Default is a space.

RS A typical application is to process a text that consists of several lines:

 foreach line [split $input \n] {
    # do something with line, produce output
    lappend outlines $out
 }
 set result [join $outlines \n]

Another is to flatten out one level of embedded lists:

 % join {1 {2 {3 4}} 5}
 1 2 {3 4} 5