lprepend

lprepend - insert elements in front of a list

lprepend listVar e ?e ..?

This is not a command included in Tcl. It is useful for implementing stacks and queues. lunshift implements the same functionality, but only for one element.

See also: lpop, lshift and Chart of existing list functionality.

Implementation

proc lprepend {listVar args} {
    upvar 1 $listVar l

    lappend l; # bring l to live.
    set l [K* [concat $args $l] [set l {}]]
}

LV you reference a function called K* - where is that implemented?

aricb I believe that's the "generalized K combinator":

 proc K* {arg args} {set arg}

LEG: Yes, it is the generalized Kombinator and sorry: here comes the "pure Tcl" implementation of lprepend:

proc lprepend {listVar args} {
    upvar 1 $listVar l

    lappend l; # bring l to live.
    set l [concat $args $l[set l {}]]
}