Ahol lista van, ott bináris fa is lehet, pl.:

vabcde = eabcd

{emptree} = vf000
{notemptree} = T{sel1of4}
{isemptree} = B{not}{notemptree}
{value} = T{sef2of4}
{left} = T{sel3of4}
{right} = T{sel4of4}
{leftemptree} = B{isemptree}{left}
{rightemptree} = B{isemptree}{right}
{isleaf}x = {and}({leftemptree}x)({rightemptree}x)

{setvalue}{tree}{val} = vt{val}({left}{tree})({right}{tree})
{setleft}{tree}{subtree} = vt({value}{tree}){subtree}({right}{tree})
{setright}{tree}[subtree} = vt({value}{tree})({left}{tree}){subtree}

{inorder}x =
  ({isemptree}x){empty}(
    {concat}
      ({append}({inorder}({left}x)({value}x))
      ({inorder}({right}x))
  )