{def removedup
 {def removedup.loop
  {lambda {:a :b}
   {if {A.empty? :a}
    then :b
    else {removedup.loop {A.rest :a}
                         {if {= {A.in? {A.first :a} :b} -1}
                          then {A.addlast! {A.first :a} :b}
                          else :b}}}}}
 {lambda {:s}
  {S.replace (\[|\]|,) by space in
   {A.disp
    {removedup.loop {A.new :s} {A.new}}}}}}
-> removedup

{removedup 1 2 3 a b c 2 3 4 b c d}
->  1 2 3 a b c 4 d