squareroot.coffee

squareRoot = ( num ) ->
  square = ( x ) -> x * x
  avg = ( x, y ) -> (x + y) / 2
  goodEnough = ( x ) -> Math.abs( square( x ) - num ) < 0.01
  improveGuess = ( x ) -> avg( x, num/x )
  iter = ( guess ) ->
    return guess if goodEnough guess
    iter improveGuess guess 
  iter 1.0

alert squareRoot 101