declare BST=node("ekran"#"screen"
         node("adapter"#"adapter"
              empty
              node("klawiatura"#"keyboard"
               empty
               empty
              )
             )
         node("komputer"#"computer"
              empty
              node("mysz"#"mouse"
               empty
               empty
              )
             )
        )

fun {LessStr A B}
   case A#B of
      nil#nil then false
   []
      nil#_ then false
   []
      _#nil then false
   []
      _#_ then
      if {StringToAtom A} < {StringToAtom B} then
     true
     else
     false
      end
   end
end

declare
fun {GetNode BT Word}
   case BT
   of node(W#T L R) then
      if W==Word then T
      elseif {LessStr W Word} then {GetNode R Word}
      else {GetNode L Word}
      end
   else raise 'brak podanego slowa' end
   end
end

%{Inspect {GetNode BST "mysz"}}

declare
fun {AddNode BT Word#Translate}
   if BT == empty then node(Word#Translate empty empty) else
   local node(W#T L R) = BT in
      if Word == W then node(Word#Translate L R)
      elseif {LessStr W Word} then node(W#T L (if R==empty then node(Word#Translate empty empty)
                     else {AddNode R Word#Translate} end)
                 )
      else node(W#T (if L==empty then node(Word#Translate empty empty)
             else {AddNode L Word#Translate} end) R)
      end
   end
   end
end

%{Inspect {AddNode BST "aaaaa"#"aaaaa"}}

declare fun {Preorder T}
           local fun {Preord T#Labels}
                    case T#Labels
                    of empty#Labels then Labels
                    [] node(V T1 T2)#Labels then
                       V|{Preord T1#{Preord T2#Labels}}
                    end
                 end
           in {Preord T#nil}
           end
    end

%{Inspect {Preorder BST}}

declare
fun {ListToTree L}
   local fun {ToTree LI BT}
        case LI
        of H|T then {ToTree T {AddNode BT H.2#H.1}}
        [] nil then BT
        end
     end
   in {ToTree L empty}
   end
end

declare LISTA = {Preorder BST}

{Inspect {ListToTree LISTA}}