declare
fun {Sqrt X}
   fun {SqrtIter Guess}
      fun {Improve}
        (Guess + X/Guess) / 2.0
      end
      fun {GoodEnough}
        {Abs X-Guess*Guess}/X < 0.00001
      end
   in
      if {GoodEnough} then Guess
      else
         {SqrtIter {Improve}}
      end
   end
   Guess=1.0
in
   {SqrtIter Guess}
end