%
% merge two file lists, organizing by filename
%
%
% stack: empty [ . . . ] empty [ . . . ]
%

[(Start)]

%
% reverse the order of the file list
%
{
 isnull ?
%
% put this entry on the bottom
%
 [Bottom]
} loop
pop

%
% remember the count of file items
%
[Count] !counter

%
% stack: empty [ . . . ]
%
{
 isnull ?
 _counter zero ?

 [Pop] -:counter
 {
  2 copy
  exch filename
  exch filename
  lt$
  {
%
% the entry to join is less than the next stack item
% push it to the bottom
%
   exch
   [Bottom]
   second isnull)
  }
  {
%
% the entry to join is greater than or equal to the next stack item
% push stack item to the bottom
%
   [Bottom]
   true
  } ifelse
  ?
 } loop

} loop

isnull
{
 _counter countup
 {
  pop
  [Pop]
  [Bottom]
 } for

}
{
 {
  isnull ?
  [Bottom]
 } loop 
} ifelse
pop

empty
[Up]
{
 pop
 [Pop]
} for

[(End)]

%
% stack: empty [ . . . ]
%