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