binary_search_rec(A, Value) = Ret =>
  Ret = binary_search_rec(A,Value, 1, A.length).

binary_search_rec(A, _Value, _Low, _High) = -1, sort(A) != A => true.
binary_search_rec(_A, _Value, Low, High)  =  0, High < Low   => true.
binary_search_rec(A, Value, Low, High)    = Mid =>
  Mid1 = (Low + High) // 2,
   if A[Mid1] > Value then
     Mid1 := binary_search_rec(A, Value, Low, Mid1-1)
   elseif A[Mid1] < Value then
     Mid1 := binary_search_rec(A, Value, Mid1+1, High)
   end,
   Mid = Mid1.